[ { "sku": "NKX17-Z", "brand": "SKF", "manufacturer_designation": "NKX 17 Z", "series": "NKX-series", "type": "needle", "d_mm": 17, "D_mm": 26, "B_mm": 25, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 12.1, "static_load_kN": 16.6, "fatigue_load_limit_kN": 1.96, "max_rpm": 7000, "reference_speed_rpm": 8500, "limiting_speed_rpm": 7000, "weight_g": 55, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "NKX 17 Z is a combined needle roller / thrust ball bearing with a caged thrust part: radial load on caged needle rollers, axial load on a ball thrust set with stamped cages, per SKF catalogue PUB BU/P1 17000 ch. 7.9. The NKX 17 Z figure gives the 17 mm Fw; the letters fix the construction — radial needle cage plus thrust ball set with pressed cages — and the Z or TN suffix only modifies the thrust part. Execution notes: the Z suffix adds a shield over the thrust balls, TN a polymer cage; the open execution allows relubrication through the shaft, the Z execution is greased for life. The minimum load factor A 0.002 applies to the thrust part: below that axial load the rolling elements of the thrust set skid, so springs or preload washers are part of the arrangement, not an afterthought. Mounting: press the unit onto the 17 mm seat against the inner faces, orient the thrust set toward the axial load, and verify the 25 mm overall height against the housing stack after fitting.", "applications": [ "turntable and swivel mounts", "machine tool feed spindles with one-direction thrust", "pump impeller shafts with steady axial pull", "gear pairs generating one-direction axial force" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "abrasive paste formation from dust ingressing past open ends without effective housing seals", "corrosion pitting from condensation in intermittently operated machinery", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "On a 17 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 26 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.", "Hardness is load capacity: in families without an inner ring the 17 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.", "The quoted 12.1/16.6 kN ratings are SKF catalogue values for this exact execution (NKX 17 Z); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKX 17 Z facing the working thrust.", "Minimum axial load is a real requirement: below factor A 0.002 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "The 12.1/16.6 kN ratings and 55 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "What are the dimensions and ratings of the NKX 17 Z?", "a": "A NKX 17 Z measures 17 mm bore/Fw × 26 mm outside diameter × 25 mm width (0.669 × 1.024 × 0.984 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 12.1 kN, static C0 16.6 kN, fatigue limit Pu 1.96 kN, limiting speed 7,000 r/min, reference speed 8,500 r/min, mass about 55 g. Axial ratings of the thrust part: dynamic Ca 10.8 kN (Ca), static C0a 19.6 kN (C0a), minimum load factor A 0.002; the thrust set carries load in one direction only." }, { "q": "How is the NKX 17 Z designation read?", "a": "NKX = needle roller radial part + caged thrust ball part for a 17 mm shaft: 26 mm OD, 25 mm overall height. The caged thrust part trades some axial capacity for higher permissible speed versus NX." }, { "q": "Can the NKX 17 Z run on an unhardened shaft?", "a": "The radial needle part of the NKX 17 Z runs directly on the 17 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "How should the NKX 17 Z be mounted?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 17 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." } ], "cross_ref": [ { "equiv_sku": "NKX17", "equiv_brand": "SKF", "level": "full", "note": "Same 17×26×25 mm envelope and equivalent catalogue ratings; NKX17 is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NKXR17", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (17×26×25 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR17-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (17×26×25 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX17-Z", "NKX 17 Z" ], "locale_variants": {} }, { "sku": "NKX17", "brand": "SKF", "manufacturer_designation": "NKX 17", "series": "NKX-series", "type": "needle", "d_mm": 17, "D_mm": 26, "B_mm": 25, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 12.1, "static_load_kN": 16.6, "fatigue_load_limit_kN": 1.96, "max_rpm": 12000, "reference_speed_rpm": 8500, "limiting_speed_rpm": 12000, "weight_g": 53, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "NKX 17 integrates two bearings in one envelope: needle rollers for the radial load on a 17 mm seat, and a cage-held thrust ball set for axial loads up to 10.8 kN (Ca) dynamic. The NKX 17 figure gives the 17 mm Fw; the letters fix the construction — radial needle cage plus thrust ball set with pressed cages — and the Z or TN suffix only modifies the thrust part. Caged thrust balls allow higher speeds than the full complement NX execution in the same envelope; the trade-off is a somewhat lower axial rating — compare the Ca figures before choosing. The minimum load factor A 0.002 applies to the thrust part: below that axial load the rolling elements of the thrust set skid, so springs or preload washers are part of the arrangement, not an afterthought. The caged thrust part survives moderate speed only with the Z shield intact — damaged shields admit grit straight into the ball raceways, and the narrow section leaves no margin.", "applications": [ "turntable and swivel mounts", "machine tool feed spindles with one-direction thrust", "pump impeller shafts with steady axial pull", "gear pairs generating one-direction axial force" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "brinelling of raceways from impact or pressing force transmitted through the rolling elements", "thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry" ], "pitfalls": [ "On a 17 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 26 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.", "Oscillating pivots fail differently: rocking through a small angle concentrates wear in the same roller positions — inspect those zones, and consider rotating the assembly's clock position at service intervals.", "Contamination, not fatigue, kills most small needle bearings: with raceways this narrow, one hard particle dents a full-width line — seal the housing even when the bearing execution itself is open.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKX 17 facing the working thrust.", "Minimum axial load is a real requirement: below factor A 0.002 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "The 12.1/16.6 kN ratings and 53 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "What limits the service life of a NKX 17?", "a": "Beyond the L10 rating, the practical limits are journal/raceway hardness for the 17 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 4.5 mm radial section leaves no reserve once a raceway is dented or ribboned." }, { "q": "What are the dimensions and ratings of the NKX 17?", "a": "A NKX 17 measures 17 mm bore/Fw × 26 mm outside diameter × 25 mm width (0.669 × 1.024 × 0.984 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 12.1 kN, static C0 16.6 kN, fatigue limit Pu 1.96 kN, limiting speed 12,000 r/min, reference speed 8,500 r/min, mass about 53 g. Axial ratings of the thrust part: dynamic Ca 10.8 kN (Ca), static C0a 19.6 kN (C0a), minimum load factor A 0.002; the thrust set carries load in one direction only." }, { "q": "How is the NKX 17 designation read?", "a": "NKX = needle roller radial part + caged thrust ball part for a 17 mm shaft: 26 mm OD, 25 mm overall height. The caged thrust part trades some axial capacity for higher permissible speed versus NX." }, { "q": "Can the NKX 17 run on an unhardened shaft?", "a": "The radial needle part of the NKX 17 runs directly on the 17 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." } ], "cross_ref": [ { "equiv_sku": "NKX17-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 17×26×25 mm envelope and equivalent catalogue ratings; NKX17-Z is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NKXR17", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (17×26×25 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR17-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (17×26×25 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX17", "NKX 17" ], "locale_variants": {} }, { "sku": "NKX20-Z", "brand": "SKF", "manufacturer_designation": "NKX 20 Z", "series": "NKX-series", "type": "needle", "d_mm": 20, "D_mm": 30, "B_mm": 30, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 16.5, "static_load_kN": 25.5, "fatigue_load_limit_kN": 3.05, "max_rpm": 6000, "reference_speed_rpm": 7500, "limiting_speed_rpm": 6000, "weight_g": 90, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "NKX 20 Z integrates two bearings in one envelope: needle rollers for the radial load on a 20 mm seat, and a cage-held thrust ball set for axial loads up to 14.3 kN (Ca) dynamic. Reading the designation: NKX marks needle roller + caged thrust ball, the number the 20 mm shaft seat; the 30 mm OD and 30 mm overall height come from the series plan. The thrust part takes axial load in one direction only; mount it facing the working load and provide a separate locating bearing for reverse events. Speed ceilings differ by part: 7,500 r/min thermal reference and 6,000 r/min limiting — the thrust element governs, since its washer faces see sliding components of contact. Apply the working axial load after mounting and re-check running torque; a rising torque in the first minutes signals balls climbing the washer lip under reversed thrust.", "applications": [ "machine tool feed spindles with one-direction thrust", "pump impeller shafts with steady axial pull", "gear pairs generating one-direction axial force", "rotary indexing tables under combined load" ], "failure_modes": [ "needle edge loading and raceway denting when the shaft deflects beyond the compensation range", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "hard-particle indentation in unfiltered lubricant", "thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry" ], "pitfalls": [ "On a 20 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 30 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.", "Reference and limiting speeds are different limits: the 7,500 r/min reference is the thermal criterion under load, The limiting value is mechanical; the reference value is thermal under load, and grease choice moves it substantially.", "Hardness is load capacity: in families without an inner ring the 20 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKX 20 Z facing the working thrust.", "Minimum axial load is a real requirement: below factor A 0.0038 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "The 16.5/25.5 kN ratings and 90 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "What mounting mistakes ruin a NKX 20 Z?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 20 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "Is the NKX 20 Z sealed?", "a": "No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty." }, { "q": "Which dimensions does the NKX 20 Z have?", "a": "A NKX 20 Z measures 20 mm bore/Fw × 30 mm outside diameter × 30 mm width (0.787 × 1.181 × 1.181 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 16.5 kN, static C0 25.5 kN, fatigue limit Pu 3.05 kN, limiting speed 6,000 r/min, reference speed 7,500 r/min, mass about 90 g. Axial ratings of the thrust part: dynamic Ca 14.3 kN (Ca), static C0a 27 kN (C0a), minimum load factor A 0.0038; the thrust set carries load in one direction only." }, { "q": "What does NKX 20 Z mean in SKF part numbering?", "a": "NKX = needle roller radial part + caged thrust ball part for a 20 mm shaft: 30 mm OD, 30 mm overall height. The caged thrust part trades some axial capacity for higher permissible speed versus NX." } ], "cross_ref": [ { "equiv_sku": "NKX20", "equiv_brand": "SKF", "level": "full", "note": "Same 20×30×30 mm envelope and equivalent catalogue ratings; NKX20 is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NKXR20", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (20×30×30 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR20-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (20×30×30 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX20-Z", "NKX 20 Z" ], "locale_variants": {} }, { "sku": "NKX20", "brand": "SKF", "manufacturer_designation": "NKX 20", "series": "NKX-series", "type": "needle", "d_mm": 20, "D_mm": 30, "B_mm": 30, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 16.5, "static_load_kN": 25.5, "fatigue_load_limit_kN": 3.05, "max_rpm": 10000, "reference_speed_rpm": 7500, "limiting_speed_rpm": 10000, "weight_g": 83, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "For a 20 mm shaft under radial plus one-direction axial load, NKX 20 from the combined needle roller / thrust ball bearings with caged thrust part provides both in 30×30 mm: needle roller cage below, caged thrust ball set above. The code NKX 20 reads as combined radial/thrust for a 20 mm shaft; the catalogue height 30 mm stacks the radial cage and the thrust set, and the 30 mm OD seats both parts in one bore. Caged thrust balls allow higher speeds than the full complement NX execution in the same envelope; the trade-off is a somewhat lower axial rating — compare the Ca figures before choosing. The minimum load factor A 0.0038 applies to the thrust part: below that axial load the rolling elements of the thrust set skid, so springs or preload washers are part of the arrangement, not an afterthought. Mounting: press the unit onto the 20 mm seat against the inner faces, orient the thrust set toward the axial load, and verify the 30 mm overall height against the housing stack after fitting.", "applications": [ "turntable and swivel mounts", "machine tool feed spindles with one-direction thrust", "pump impeller shafts with steady axial pull", "gear pairs generating one-direction axial force" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "corrosion pitting from condensation in intermittently operated machinery", "thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry" ], "pitfalls": [ "On a 20 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 30 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.", "Do not interchange envelope-identical needle families blindly: NKX 20 shares its 20×30×30 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.", "Reference and limiting speeds are different limits: the 7,500 r/min reference is the thermal criterion under load, The limiting value is mechanical; the reference value is thermal under load, and grease choice moves it substantially.", "Height stack-up is easy to mis-check: the thrust-washer part adds height beyond a plain needle bearing, and clamping the stack solid over it preloads the thrust set beyond its rating.", "Do not treat the axial rating 14.3 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.", "The 16.5/25.5 kN ratings and 83 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "How should the NKX 20 be mounted?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 20 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "What limits the service life of a NKX 20?", "a": "Beyond the L10 rating, the practical limits are journal/raceway hardness for the 20 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 5.0 mm radial section leaves no reserve once a raceway is dented or ribboned." }, { "q": "What are the dimensions and ratings of the NKX 20?", "a": "A NKX 20 measures 20 mm bore/Fw × 30 mm outside diameter × 30 mm width (0.787 × 1.181 × 1.181 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 16.5 kN, static C0 25.5 kN, fatigue limit Pu 3.05 kN, limiting speed 10,000 r/min, reference speed 7,500 r/min, mass about 83 g. Axial ratings of the thrust part: dynamic Ca 14.3 kN (Ca), static C0a 27 kN (C0a), minimum load factor A 0.0038; the thrust set carries load in one direction only." }, { "q": "How is the NKX 20 designation read?", "a": "NKX = needle roller radial part + caged thrust ball part for a 20 mm shaft: 30 mm OD, 30 mm overall height. The caged thrust part trades some axial capacity for higher permissible speed versus NX." } ], "cross_ref": [ { "equiv_sku": "NKX20-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 20×30×30 mm envelope and equivalent catalogue ratings; NKX20-Z is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NKXR20", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (20×30×30 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR20-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (20×30×30 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX20", "NKX 20" ], "locale_variants": {} }, { "sku": "NKX25-Z", "brand": "SKF", "manufacturer_designation": "NKX 25 Z", "series": "NKX-series", "type": "needle", "d_mm": 25, "D_mm": 37, "B_mm": 30, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 19, "static_load_kN": 32.5, "fatigue_load_limit_kN": 4, "max_rpm": 5500, "reference_speed_rpm": 6300, "limiting_speed_rpm": 5500, "weight_g": 130, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "For a 25 mm shaft under radial plus one-direction axial load, NKX 25 Z from the combined needle roller / thrust ball bearings with caged thrust part provides both in 37×30 mm: needle roller cage below, caged thrust ball set above. The code NKX 25 Z reads as combined radial/thrust for a 25 mm shaft; the catalogue height 30 mm stacks the radial cage and the thrust set, and the 37 mm OD seats both parts in one bore. The thrust part takes axial load in one direction only; mount it facing the working load and provide a separate locating bearing for reverse events. Speed ceilings differ by part: 6,300 r/min thermal reference and 5,500 r/min limiting — the thrust element governs, since its washer faces see sliding components of contact. The caged thrust part survives moderate speed only with the Z shield intact — damaged shields admit grit straight into the ball raceways, and the narrow section leaves no margin.", "applications": [ "machine tool feed spindles with one-direction thrust", "pump impeller shafts with steady axial pull", "gear pairs generating one-direction axial force", "rotary indexing tables under combined load" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "cage pocket wear and roller skew after sustained operation with too little radial preload", "abrasive paste formation from dust ingressing past open ends without effective housing seals", "false brinelling of standby equipment under external vibration", "thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry" ], "pitfalls": [ "On a 25 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 37 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.", "Do not interchange envelope-identical needle families blindly: NKX 25 Z shares its 25×37×30 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.", "Reference and limiting speeds are different limits: the 6,300 r/min reference is the thermal criterion under load, The limiting value is mechanical; the reference value is thermal under load, and grease choice moves it substantially.", "Do not treat the axial rating 19.5 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKX 25 Z facing the working thrust.", "The 19/32.5 kN ratings and 130 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "What limits the service life of a NKX 25 Z?", "a": "Beyond the L10 rating, the practical limits are journal/raceway hardness for the 25 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 6.0 mm radial section leaves no reserve once a raceway is dented or ribboned." }, { "q": "What are the dimensions and ratings of the NKX 25 Z?", "a": "A NKX 25 Z measures 25 mm bore/Fw × 37 mm outside diameter × 30 mm width (0.984 × 1.457 × 1.181 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 19 kN, static C0 32.5 kN, fatigue limit Pu 4 kN, limiting speed 5,500 r/min, reference speed 6,300 r/min, mass about 130 g. Axial ratings of the thrust part: dynamic Ca 19.5 kN (Ca), static C0a 40.5 kN (C0a), minimum load factor A 0.0085; the thrust set carries load in one direction only." }, { "q": "How is the NKX 25 Z designation read?", "a": "NKX = needle roller radial part + caged thrust ball part for a 25 mm shaft: 37 mm OD, 30 mm overall height. The caged thrust part trades some axial capacity for higher permissible speed versus NX." }, { "q": "Can the NKX 25 Z run on an unhardened shaft?", "a": "The radial needle part of the NKX 25 Z runs directly on the 25 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." } ], "cross_ref": [ { "equiv_sku": "NKX25", "equiv_brand": "SKF", "level": "full", "note": "Same 25×37×30 mm envelope and equivalent catalogue ratings; NKX25 is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "RNA6904", "equiv_brand": "SKF", "level": "partial", "note": "Same 25×37×30 mm envelope, but catalogue C/C0 differ between the executions (19/32.5 vs 35.2/53 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NX25-Z", "equiv_brand": "SKF", "level": "partial", "note": "Same 25×37×30 mm envelope, but catalogue C/C0 differ between the executions (19/32.5 vs 15.1/24.5 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NX25", "equiv_brand": "SKF", "level": "partial", "note": "Same 25×37×30 mm envelope, but catalogue C/C0 differ between the executions (19/32.5 vs 15.1/24.5 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NKXR25", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (25×37×30 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR25-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (25×37×30 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX25-Z", "NKX 25 Z" ], "locale_variants": {} }, { "sku": "NKX25", "brand": "SKF", "manufacturer_designation": "NKX 25", "series": "NKX-series", "type": "needle", "d_mm": 25, "D_mm": 37, "B_mm": 30, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 19, "static_load_kN": 32.5, "fatigue_load_limit_kN": 4, "max_rpm": 9000, "reference_speed_rpm": 6300, "limiting_speed_rpm": 9000, "weight_g": 130, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "SKF supplies NKX 25 for combined-load positions at moderate speed: the caged thrust balls reduce friction and allow 6,300 r/min reference where a full complement NX would overheat. Reading the designation: NKX marks needle roller + caged thrust ball, the number the 25 mm shaft seat; the 37 mm OD and 30 mm overall height come from the series plan. The thrust part takes axial load in one direction only; mount it facing the working load and provide a separate locating bearing for reverse events. Axial capability is one-direction: size the arrangement so working thrust pushes the thrust-washer face, and provide a mirrored unit or separate bearing for load reversals. Mounting: press the unit onto the 25 mm seat against the inner faces, orient the thrust set toward the axial load, and verify the 30 mm overall height against the housing stack after fitting.", "applications": [ "turntable and swivel mounts", "machine tool feed spindles with one-direction thrust", "pump impeller shafts with steady axial pull", "gear pairs generating one-direction axial force" ], "failure_modes": [ "needle edge loading and raceway denting when the shaft deflects beyond the compensation range", "cage pocket wear and roller skew after sustained operation with too little radial preload", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "rolling-contact fatigue spalling after the rated L10 life", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "On a 25 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 37 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.", "Reference and limiting speeds are different limits: the 6,300 r/min reference is the thermal criterion under load, The limiting value is mechanical; the reference value is thermal under load, and grease choice moves it substantially.", "Hardness is load capacity: in families without an inner ring the 25 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.", "Minimum axial load is a real requirement: below factor A 0.0085 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "Height stack-up is easy to mis-check: the thrust-washer part adds height beyond a plain needle bearing, and clamping the stack solid over it preloads the thrust set beyond its rating.", "The 19/32.5 kN ratings and 130 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "What mounting mistakes ruin a NKX 25?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 25 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "Is the NKX 25 sealed?", "a": "No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty." }, { "q": "Which dimensions does the NKX 25 have?", "a": "A NKX 25 measures 25 mm bore/Fw × 37 mm outside diameter × 30 mm width (0.984 × 1.457 × 1.181 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 19 kN, static C0 32.5 kN, fatigue limit Pu 4 kN, limiting speed 9,000 r/min, reference speed 6,300 r/min, mass about 130 g. Axial ratings of the thrust part: dynamic Ca 19.5 kN (Ca), static C0a 40.5 kN (C0a), minimum load factor A 0.0085; the thrust set carries load in one direction only." }, { "q": "What does NKX 25 mean in SKF part numbering?", "a": "NKX = needle roller radial part + caged thrust ball part for a 25 mm shaft: 37 mm OD, 30 mm overall height. The caged thrust part trades some axial capacity for higher permissible speed versus NX." } ], "cross_ref": [ { "equiv_sku": "NKX25-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 25×37×30 mm envelope and equivalent catalogue ratings; NKX25-Z is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "RNA6904", "equiv_brand": "SKF", "level": "partial", "note": "Same 25×37×30 mm envelope, but catalogue C/C0 differ between the executions (19/32.5 vs 35.2/53 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NX25-Z", "equiv_brand": "SKF", "level": "partial", "note": "Same 25×37×30 mm envelope, but catalogue C/C0 differ between the executions (19/32.5 vs 15.1/24.5 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NX25", "equiv_brand": "SKF", "level": "partial", "note": "Same 25×37×30 mm envelope, but catalogue C/C0 differ between the executions (19/32.5 vs 15.1/24.5 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NKXR25", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (25×37×30 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR25-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (25×37×30 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX25", "NKX 25" ], "locale_variants": {} }, { "sku": "NKX30-Z", "brand": "SKF", "manufacturer_designation": "NKX 30 Z", "series": "NKX-series", "type": "needle", "d_mm": 30, "D_mm": 42, "B_mm": 30, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 22.9, "static_load_kN": 38, "fatigue_load_limit_kN": 4.8, "max_rpm": 5000, "reference_speed_rpm": 6000, "limiting_speed_rpm": 5000, "weight_g": 140, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "In SKF catalogue PUB BU/P1 17000, NKX 30 Z designates a combined bearing with needle roller radial part and caged thrust ball part: 30 mm shaft seat, 42 mm OD, thrust dynamic rating 20.3 kN (Ca). The NKX 30 Z figure gives the 30 mm Fw; the letters fix the construction — radial needle cage plus thrust ball set with pressed cages — and the Z or TN suffix only modifies the thrust part. The thrust part takes axial load in one direction only; mount it facing the working load and provide a separate locating bearing for reverse events. The minimum load factor A 0.01 applies to the thrust part: below that axial load the rolling elements of the thrust set skid, so springs or preload washers are part of the arrangement, not an afterthought. The caged thrust part survives moderate speed only with the Z shield intact — damaged shields admit grit straight into the ball raceways, and the narrow section leaves no margin.", "applications": [ "turntable and swivel mounts", "machine tool feed spindles with one-direction thrust", "pump impeller shafts with steady axial pull", "gear pairs generating one-direction axial force" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "abrasive paste formation from dust ingressing past open ends without effective housing seals", "brinelling of raceways from impact or pressing force transmitted through the rolling elements", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "At 30 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 30 mm seats can bend past the compensation range long before the load rating is exhausted.", "Hardness is load capacity: in families without an inner ring the 30 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.", "The quoted 22.9/38 kN ratings are SKF catalogue values for this exact execution (NKX 30 Z); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKX 30 Z facing the working thrust.", "Minimum axial load is a real requirement: below factor A 0.01 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "The 22.9/38 kN ratings and 140 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "How should the NKX 30 Z be mounted?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 30 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "What limits the service life of a NKX 30 Z?", "a": "Beyond the L10 rating, the practical limits are journal/raceway hardness for the 30 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 6.0 mm radial section leaves no reserve once a raceway is dented or ribboned." }, { "q": "What are the dimensions and ratings of the NKX 30 Z?", "a": "A NKX 30 Z measures 30 mm bore/Fw × 42 mm outside diameter × 30 mm width (1.181 × 1.654 × 1.181 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 22.9 kN, static C0 38 kN, fatigue limit Pu 4.8 kN, limiting speed 5,000 r/min, reference speed 6,000 r/min, mass about 140 g. Axial ratings of the thrust part: dynamic Ca 20.3 kN (Ca), static C0a 45.5 kN (C0a), minimum load factor A 0.01; the thrust set carries load in one direction only." }, { "q": "How is the NKX 30 Z designation read?", "a": "NKX = needle roller radial part + caged thrust ball part for a 30 mm shaft: 42 mm OD, 30 mm overall height. The caged thrust part trades some axial capacity for higher permissible speed versus NX." } ], "cross_ref": [ { "equiv_sku": "NKX30", "equiv_brand": "SKF", "level": "full", "note": "Same 30×42×30 mm envelope and equivalent catalogue ratings; NKX30 is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "RNA6905", "equiv_brand": "SKF", "level": "partial", "note": "Same 30×42×30 mm envelope, but catalogue C/C0 differ between the executions (22.9/38 vs 38/62 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NX30-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (30×42×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NX30", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (30×42×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR30", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (30×42×30 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR30-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (30×42×30 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX30-Z", "NKX 30 Z" ], "locale_variants": {} }, { "sku": "NKX30", "brand": "SKF", "manufacturer_designation": "NKX 30", "series": "NKX-series", "type": "needle", "d_mm": 30, "D_mm": 42, "B_mm": 30, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 22.9, "static_load_kN": 38, "fatigue_load_limit_kN": 4.8, "max_rpm": 8500, "reference_speed_rpm": 6000, "limiting_speed_rpm": 8500, "weight_g": 140, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "In SKF catalogue PUB BU/P1 17000, NKX 30 designates a combined bearing with needle roller radial part and caged thrust ball part: 30 mm shaft seat, 42 mm OD, thrust dynamic rating 20.3 kN (Ca). Reading the designation: NKX marks needle roller + caged thrust ball, the number the 30 mm shaft seat; the 42 mm OD and 30 mm overall height come from the series plan. Execution notes: the Z suffix adds a shield over the thrust balls, TN a polymer cage; the open execution allows relubrication through the shaft, the Z execution is greased for life. Axial capability is one-direction: size the arrangement so working thrust pushes the thrust-washer face, and provide a mirrored unit or separate bearing for load reversals. Apply the working axial load after mounting and re-check running torque; a rising torque in the first minutes signals balls climbing the washer lip under reversed thrust.", "applications": [ "turntable and swivel mounts", "machine tool feed spindles with one-direction thrust", "pump impeller shafts with steady axial pull", "gear pairs generating one-direction axial force" ], "failure_modes": [ "needle edge loading and raceway denting when the shaft deflects beyond the compensation range", "cage pocket wear and roller skew after sustained operation with too little radial preload", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "electrical erosion on VFD-driven shafts without brush or insulated mounting", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "At 30 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 30 mm seats can bend past the compensation range long before the load rating is exhausted.", "Reference and limiting speeds are different limits: the 6,000 r/min reference is the thermal criterion under load, The limiting value is mechanical; the reference value is thermal under load, and grease choice moves it substantially.", "Hardness is load capacity: in families without an inner ring the 30 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.", "Minimum axial load is a real requirement: below factor A 0.01 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "Height stack-up is easy to mis-check: the thrust-washer part adds height beyond a plain needle bearing, and clamping the stack solid over it preloads the thrust set beyond its rating.", "The 22.9/38 kN ratings and 140 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "Which dimensions does the NKX 30 have?", "a": "A NKX 30 measures 30 mm bore/Fw × 42 mm outside diameter × 30 mm width (1.181 × 1.654 × 1.181 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 22.9 kN, static C0 38 kN, fatigue limit Pu 4.8 kN, limiting speed 8,500 r/min, reference speed 6,000 r/min, mass about 140 g. Axial ratings of the thrust part: dynamic Ca 20.3 kN (Ca), static C0a 45.5 kN (C0a), minimum load factor A 0.01; the thrust set carries load in one direction only." }, { "q": "What does NKX 30 mean in SKF part numbering?", "a": "NKX = needle roller radial part + caged thrust ball part for a 30 mm shaft: 42 mm OD, 30 mm overall height. The caged thrust part trades some axial capacity for higher permissible speed versus NX." }, { "q": "Does the NKX 30 need a hardened and ground shaft?", "a": "The radial needle part of the NKX 30 runs directly on the 30 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "What mounting mistakes ruin a NKX 30?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 30 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." } ], "cross_ref": [ { "equiv_sku": "NKX30-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 30×42×30 mm envelope and equivalent catalogue ratings; NKX30-Z is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "RNA6905", "equiv_brand": "SKF", "level": "partial", "note": "Same 30×42×30 mm envelope, but catalogue C/C0 differ between the executions (22.9/38 vs 38/62 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NX30-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (30×42×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NX30", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (30×42×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR30", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (30×42×30 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR30-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (30×42×30 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX30", "NKX 30" ], "locale_variants": {} }, { "sku": "NKX35-Z", "brand": "SKF", "manufacturer_designation": "NKX 35 Z", "series": "NKX-series", "type": "needle", "d_mm": 35, "D_mm": 47, "B_mm": 30, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 24.6, "static_load_kN": 45, "fatigue_load_limit_kN": 5.6, "max_rpm": 4500, "reference_speed_rpm": 5600, "limiting_speed_rpm": 4500, "weight_g": 170, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "For a 35 mm shaft under radial plus one-direction axial load, NKX 35 Z from the combined needle roller / thrust ball bearings with caged thrust part provides both in 47×30 mm: needle roller cage below, caged thrust ball set above. The code NKX 35 Z reads as combined radial/thrust for a 35 mm shaft; the catalogue height 30 mm stacks the radial cage and the thrust set, and the 47 mm OD seats both parts in one bore. Execution notes: the Z suffix adds a shield over the thrust balls, TN a polymer cage; the open execution allows relubrication through the shaft, the Z execution is greased for life. Speed ceilings differ by part: 5,600 r/min thermal reference and 4,500 r/min limiting — the thrust element governs, since its washer faces see sliding components of contact. Apply the working axial load after mounting and re-check running torque; a rising torque in the first minutes signals balls climbing the washer lip under reversed thrust.", "applications": [ "machine tool feed spindles with one-direction thrust", "pump impeller shafts with steady axial pull", "gear pairs generating one-direction axial force", "rotary indexing tables under combined load" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "cage pocket wear and roller skew after sustained operation with too little radial preload", "abrasive paste formation from dust ingressing past open ends without effective housing seals", "electrical erosion on VFD-driven shafts without brush or insulated mounting", "thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry" ], "pitfalls": [ "At 35 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 35 mm seats can bend past the compensation range long before the load rating is exhausted.", "Hardness is load capacity: in families without an inner ring the 35 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.", "The quoted 24.6/45 kN ratings are SKF catalogue values for this exact execution (NKX 35 Z); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.", "Do not treat the axial rating 21.2 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKX 35 Z facing the working thrust.", "The 24.6/45 kN ratings and 170 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "What limits the service life of a NKX 35 Z?", "a": "Beyond the L10 rating, the practical limits are journal/raceway hardness for the 35 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 6.0 mm radial section leaves no reserve once a raceway is dented or ribboned." }, { "q": "What are the dimensions and ratings of the NKX 35 Z?", "a": "A NKX 35 Z measures 35 mm bore/Fw × 47 mm outside diameter × 30 mm width (1.378 × 1.85 × 1.181 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 24.6 kN, static C0 45 kN, fatigue limit Pu 5.6 kN, limiting speed 4,500 r/min, reference speed 5,600 r/min, mass about 170 g. Axial ratings of the thrust part: dynamic Ca 21.2 kN (Ca), static C0a 51 kN (C0a), minimum load factor A 0.013; the thrust set carries load in one direction only." }, { "q": "How is the NKX 35 Z designation read?", "a": "NKX = needle roller radial part + caged thrust ball part for a 35 mm shaft: 47 mm OD, 30 mm overall height. The caged thrust part trades some axial capacity for higher permissible speed versus NX." }, { "q": "Can the NKX 35 Z run on an unhardened shaft?", "a": "The radial needle part of the NKX 35 Z runs directly on the 35 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." } ], "cross_ref": [ { "equiv_sku": "NKX35", "equiv_brand": "SKF", "level": "full", "note": "Same 35×47×30 mm envelope and equivalent catalogue ratings; NKX35 is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "RNA6906", "equiv_brand": "SKF", "level": "partial", "note": "Same 35×47×30 mm envelope, but catalogue C/C0 differ between the executions (24.6/45 vs 42.9/75 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NX35-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (35×47×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NX35", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (35×47×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR35", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (35×47×30 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR35-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (35×47×30 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX35-Z", "NKX 35 Z" ], "locale_variants": {} }, { "sku": "NKX35", "brand": "SKF", "manufacturer_designation": "NKX 35", "series": "NKX-series", "type": "needle", "d_mm": 35, "D_mm": 47, "B_mm": 30, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 24.6, "static_load_kN": 45, "fatigue_load_limit_kN": 5.6, "max_rpm": 7500, "reference_speed_rpm": 5600, "limiting_speed_rpm": 7500, "weight_g": 160, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "The combined needle roller / thrust ball bearings with caged thrust part execution NKX 35 measures 35×47×30 mm and carries radial load 24.6 kN dynamic plus one-direction axial load 21.2 kN (Ca) — the caged thrust part runs at higher speed than full complement NX types. The NKX 35 figure gives the 35 mm Fw; the letters fix the construction — radial needle cage plus thrust ball set with pressed cages — and the Z or TN suffix only modifies the thrust part. Caged thrust balls allow higher speeds than the full complement NX execution in the same envelope; the trade-off is a somewhat lower axial rating — compare the Ca figures before choosing. The minimum load factor A 0.013 applies to the thrust part: below that axial load the rolling elements of the thrust set skid, so springs or preload washers are part of the arrangement, not an afterthought. Apply the working axial load after mounting and re-check running torque; a rising torque in the first minutes signals balls climbing the washer lip under reversed thrust.", "applications": [ "turntable and swivel mounts", "machine tool feed spindles with one-direction thrust", "pump impeller shafts with steady axial pull", "gear pairs generating one-direction axial force" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "hard-particle indentation in unfiltered lubricant", "thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry" ], "pitfalls": [ "At 35 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 35 mm seats can bend past the compensation range long before the load rating is exhausted.", "Hardness is load capacity: in families without an inner ring the 35 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.", "The quoted 24.6/45 kN ratings are SKF catalogue values for this exact execution (NKX 35); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKX 35 facing the working thrust.", "Minimum axial load is a real requirement: below factor A 0.013 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "The 24.6/45 kN ratings and 160 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "What are the dimensions and ratings of the NKX 35?", "a": "A NKX 35 measures 35 mm bore/Fw × 47 mm outside diameter × 30 mm width (1.378 × 1.85 × 1.181 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 24.6 kN, static C0 45 kN, fatigue limit Pu 5.6 kN, limiting speed 7,500 r/min, reference speed 5,600 r/min, mass about 160 g. Axial ratings of the thrust part: dynamic Ca 21.2 kN (Ca), static C0a 51 kN (C0a), minimum load factor A 0.013; the thrust set carries load in one direction only." }, { "q": "How is the NKX 35 designation read?", "a": "NKX = needle roller radial part + caged thrust ball part for a 35 mm shaft: 47 mm OD, 30 mm overall height. The caged thrust part trades some axial capacity for higher permissible speed versus NX." }, { "q": "Can the NKX 35 run on an unhardened shaft?", "a": "The radial needle part of the NKX 35 runs directly on the 35 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "How should the NKX 35 be mounted?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 35 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." } ], "cross_ref": [ { "equiv_sku": "NKX35-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 35×47×30 mm envelope and equivalent catalogue ratings; NKX35-Z is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "RNA6906", "equiv_brand": "SKF", "level": "partial", "note": "Same 35×47×30 mm envelope, but catalogue C/C0 differ between the executions (24.6/45 vs 42.9/75 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NX35-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (35×47×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NX35", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (35×47×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR35", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (35×47×30 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR35-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (35×47×30 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX35", "NKX 35" ], "locale_variants": {} }, { "sku": "NKX40-Z", "brand": "SKF", "manufacturer_designation": "NKX 40 Z", "series": "NKX-series", "type": "needle", "d_mm": 40, "D_mm": 52, "B_mm": 32, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 26.4, "static_load_kN": 51, "fatigue_load_limit_kN": 6.3, "max_rpm": 4000, "reference_speed_rpm": 5000, "limiting_speed_rpm": 4000, "weight_g": 210, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "In SKF catalogue PUB BU/P1 17000, NKX 40 Z designates a combined bearing with needle roller radial part and caged thrust ball part: 40 mm shaft seat, 52 mm OD, thrust dynamic rating 27 kN (Ca). The NKX 40 Z figure gives the 40 mm Fw; the letters fix the construction — radial needle cage plus thrust ball set with pressed cages — and the Z or TN suffix only modifies the thrust part. Execution notes: the Z suffix adds a shield over the thrust balls, TN a polymer cage; the open execution allows relubrication through the shaft, the Z execution is greased for life. The minimum load factor A 0.024 applies to the thrust part: below that axial load the rolling elements of the thrust set skid, so springs or preload washers are part of the arrangement, not an afterthought. Apply the working axial load after mounting and re-check running torque; a rising torque in the first minutes signals balls climbing the washer lip under reversed thrust.", "applications": [ "turntable and swivel mounts", "machine tool feed spindles with one-direction thrust", "pump impeller shafts with steady axial pull", "gear pairs generating one-direction axial force" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "abrasive paste formation from dust ingressing past open ends without effective housing seals", "hard-particle indentation in unfiltered lubricant", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "At 40 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 40 mm seats can bend past the compensation range long before the load rating is exhausted.", "Oscillating pivots fail differently: rocking through a small angle concentrates wear in the same roller positions — inspect those zones, and consider rotating the assembly's clock position at service intervals.", "Contamination, not fatigue, kills most small needle bearings: with raceways this narrow, one hard particle dents a full-width line — seal the housing even when the bearing execution itself is open.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKX 40 Z facing the working thrust.", "Minimum axial load is a real requirement: below factor A 0.024 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "The 26.4/51 kN ratings and 210 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "How should the NKX 40 Z be mounted?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 40 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "What limits the service life of a NKX 40 Z?", "a": "Beyond the L10 rating, the practical limits are journal/raceway hardness for the 40 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 6.0 mm radial section leaves no reserve once a raceway is dented or ribboned." }, { "q": "What are the dimensions and ratings of the NKX 40 Z?", "a": "A NKX 40 Z measures 40 mm bore/Fw × 52 mm outside diameter × 32 mm width (1.575 × 2.047 × 1.26 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 26.4 kN, static C0 51 kN, fatigue limit Pu 6.3 kN, limiting speed 4,000 r/min, reference speed 5,000 r/min, mass about 210 g. Axial ratings of the thrust part: dynamic Ca 27 kN (Ca), static C0a 68 kN (C0a), minimum load factor A 0.024; the thrust set carries load in one direction only." }, { "q": "How is the NKX 40 Z designation read?", "a": "NKX = needle roller radial part + caged thrust ball part for a 40 mm shaft: 52 mm OD, 32 mm overall height. The caged thrust part trades some axial capacity for higher permissible speed versus NX." } ], "cross_ref": [ { "equiv_sku": "NKX40", "equiv_brand": "SKF", "level": "full", "note": "Same 40×52×32 mm envelope and equivalent catalogue ratings; NKX40 is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NKXR40", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (40×52×32 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR40-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (40×52×32 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX40-Z", "NKX 40 Z" ], "locale_variants": {} }, { "sku": "NKX40", "brand": "SKF", "manufacturer_designation": "NKX 40", "series": "NKX-series", "type": "needle", "d_mm": 40, "D_mm": 52, "B_mm": 32, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 26.4, "static_load_kN": 51, "fatigue_load_limit_kN": 6.3, "max_rpm": 7000, "reference_speed_rpm": 5000, "limiting_speed_rpm": 7000, "weight_g": 200, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "For a 40 mm shaft under radial plus one-direction axial load, NKX 40 from the combined needle roller / thrust ball bearings with caged thrust part provides both in 52×32 mm: needle roller cage below, caged thrust ball set above. The NKX 40 figure gives the 40 mm Fw; the letters fix the construction — radial needle cage plus thrust ball set with pressed cages — and the Z or TN suffix only modifies the thrust part. The thrust part takes axial load in one direction only; mount it facing the working load and provide a separate locating bearing for reverse events. The minimum load factor A 0.024 applies to the thrust part: below that axial load the rolling elements of the thrust set skid, so springs or preload washers are part of the arrangement, not an afterthought. The caged thrust part survives moderate speed only with the Z shield intact — damaged shields admit grit straight into the ball raceways, and the narrow section leaves no margin.", "applications": [ "turntable and swivel mounts", "machine tool feed spindles with one-direction thrust", "pump impeller shafts with steady axial pull", "gear pairs generating one-direction axial force" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "brinelling of raceways from impact or pressing force transmitted through the rolling elements", "thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry" ], "pitfalls": [ "At 40 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 40 mm seats can bend past the compensation range long before the load rating is exhausted.", "Hardness is load capacity: in families without an inner ring the 40 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.", "The quoted 26.4/51 kN ratings are SKF catalogue values for this exact execution (NKX 40); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKX 40 facing the working thrust.", "Minimum axial load is a real requirement: below factor A 0.024 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "The 26.4/51 kN ratings and 200 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "Can the NKX 40 run on an unhardened shaft?", "a": "The radial needle part of the NKX 40 runs directly on the 40 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "How should the NKX 40 be mounted?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 40 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "What limits the service life of a NKX 40?", "a": "Beyond the L10 rating, the practical limits are journal/raceway hardness for the 40 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 6.0 mm radial section leaves no reserve once a raceway is dented or ribboned." }, { "q": "What are the dimensions and ratings of the NKX 40?", "a": "A NKX 40 measures 40 mm bore/Fw × 52 mm outside diameter × 32 mm width (1.575 × 2.047 × 1.26 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 26.4 kN, static C0 51 kN, fatigue limit Pu 6.3 kN, limiting speed 7,000 r/min, reference speed 5,000 r/min, mass about 200 g. Axial ratings of the thrust part: dynamic Ca 27 kN (Ca), static C0a 68 kN (C0a), minimum load factor A 0.024; the thrust set carries load in one direction only." } ], "cross_ref": [ { "equiv_sku": "NKX40-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 40×52×32 mm envelope and equivalent catalogue ratings; NKX40-Z is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NKXR40", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (40×52×32 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR40-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (40×52×32 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX40", "NKX 40" ], "locale_variants": {} }, { "sku": "NKX45-Z", "brand": "SKF", "manufacturer_designation": "NKX 45 Z", "series": "NKX-series", "type": "needle", "d_mm": 45, "D_mm": 58, "B_mm": 32, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 27.5, "static_load_kN": 57, "fatigue_load_limit_kN": 7.1, "max_rpm": 3800, "reference_speed_rpm": 4500, "limiting_speed_rpm": 3800, "weight_g": 270, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "SKF supplies NKX 45 Z for combined-load positions at moderate speed: the caged thrust balls reduce friction and allow 4,500 r/min reference where a full complement NX would overheat. Reading the designation: NKX marks needle roller + caged thrust ball, the number the 45 mm shaft seat; the 58 mm OD and 32 mm overall height come from the series plan. Execution notes: the Z suffix adds a shield over the thrust balls, TN a polymer cage; the open execution allows relubrication through the shaft, the Z execution is greased for life. The minimum load factor A 0.029 applies to the thrust part: below that axial load the rolling elements of the thrust set skid, so springs or preload washers are part of the arrangement, not an afterthought. The caged thrust part survives moderate speed only with the Z shield intact — damaged shields admit grit straight into the ball raceways, and the narrow section leaves no margin.", "applications": [ "turntable and swivel mounts", "machine tool feed spindles with one-direction thrust", "pump impeller shafts with steady axial pull", "gear pairs generating one-direction axial force" ], "failure_modes": [ "needle edge loading and raceway denting when the shaft deflects beyond the compensation range", "cage pocket wear and roller skew after sustained operation with too little radial preload", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "false brinelling of standby equipment under external vibration", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "At 45 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 45 mm seats can bend past the compensation range long before the load rating is exhausted.", "The quoted 27.5/57 kN ratings are SKF catalogue values for this exact execution (NKX 45 Z); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.", "Oscillating pivots fail differently: rocking through a small angle concentrates wear in the same roller positions — inspect those zones, and consider rotating the assembly's clock position at service intervals.", "Do not treat the axial rating 28.1 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKX 45 Z facing the working thrust.", "The 27.5/57 kN ratings and 270 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "Is the NKX 45 Z sealed?", "a": "No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty." }, { "q": "Which dimensions does the NKX 45 Z have?", "a": "A NKX 45 Z measures 45 mm bore/Fw × 58 mm outside diameter × 32 mm width (1.772 × 2.283 × 1.26 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 27.5 kN, static C0 57 kN, fatigue limit Pu 7.1 kN, limiting speed 3,800 r/min, reference speed 4,500 r/min, mass about 270 g. Axial ratings of the thrust part: dynamic Ca 28.1 kN (Ca), static C0a 75 kN (C0a), minimum load factor A 0.029; the thrust set carries load in one direction only." }, { "q": "What does NKX 45 Z mean in SKF part numbering?", "a": "NKX = needle roller radial part + caged thrust ball part for a 45 mm shaft: 58 mm OD, 32 mm overall height. The caged thrust part trades some axial capacity for higher permissible speed versus NX." }, { "q": "Does the NKX 45 Z need a hardened and ground shaft?", "a": "The radial needle part of the NKX 45 Z runs directly on the 45 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." } ], "cross_ref": [ { "equiv_sku": "NKX45", "equiv_brand": "SKF", "level": "full", "note": "Same 45×58×32 mm envelope and equivalent catalogue ratings; NKX45 is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NKXR45", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (45×58×32 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR45-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (45×58×32 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX45-Z", "NKX 45 Z" ], "locale_variants": {} }, { "sku": "NKX45", "brand": "SKF", "manufacturer_designation": "NKX 45", "series": "NKX-series", "type": "needle", "d_mm": 45, "D_mm": 58, "B_mm": 32, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 27.5, "static_load_kN": 57, "fatigue_load_limit_kN": 7.1, "max_rpm": 6300, "reference_speed_rpm": 4500, "limiting_speed_rpm": 6300, "weight_g": 250, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "SKF supplies NKX 45 for combined-load positions at moderate speed: the caged thrust balls reduce friction and allow 4,500 r/min reference where a full complement NX would overheat. In SKF nomenclature NKX is the combined family: the number states 45 mm, and unlike NX the thrust balls are caged, trading some axial capacity for speed and friction. Execution notes: the Z suffix adds a shield over the thrust balls, TN a polymer cage; the open execution allows relubrication through the shaft, the Z execution is greased for life. Axial capability is one-direction: size the arrangement so working thrust pushes the thrust-washer face, and provide a mirrored unit or separate bearing for load reversals. The caged thrust part survives moderate speed only with the Z shield intact — damaged shields admit grit straight into the ball raceways, and the narrow section leaves no margin.", "applications": [ "turntable and swivel mounts", "machine tool feed spindles with one-direction thrust", "pump impeller shafts with steady axial pull", "gear pairs generating one-direction axial force" ], "failure_modes": [ "needle edge loading and raceway denting when the shaft deflects beyond the compensation range", "cage pocket wear and roller skew after sustained operation with too little radial preload", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "false brinelling of standby equipment under external vibration", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "At 45 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 45 mm seats can bend past the compensation range long before the load rating is exhausted.", "The quoted 27.5/57 kN ratings are SKF catalogue values for this exact execution (NKX 45); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.", "Oscillating pivots fail differently: rocking through a small angle concentrates wear in the same roller positions — inspect those zones, and consider rotating the assembly's clock position at service intervals.", "Do not treat the axial rating 28.1 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKX 45 facing the working thrust.", "The 27.5/57 kN ratings and 250 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "Does the NKX 45 need a hardened and ground shaft?", "a": "The radial needle part of the NKX 45 runs directly on the 45 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "What mounting mistakes ruin a NKX 45?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 45 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "Is the NKX 45 sealed?", "a": "No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty." }, { "q": "Which dimensions does the NKX 45 have?", "a": "A NKX 45 measures 45 mm bore/Fw × 58 mm outside diameter × 32 mm width (1.772 × 2.283 × 1.26 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 27.5 kN, static C0 57 kN, fatigue limit Pu 7.1 kN, limiting speed 6,300 r/min, reference speed 4,500 r/min, mass about 250 g. Axial ratings of the thrust part: dynamic Ca 28.1 kN (Ca), static C0a 75 kN (C0a), minimum load factor A 0.029; the thrust set carries load in one direction only." } ], "cross_ref": [ { "equiv_sku": "NKX45-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 45×58×32 mm envelope and equivalent catalogue ratings; NKX45-Z is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NKXR45", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (45×58×32 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR45-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (45×58×32 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX45", "NKX 45" ], "locale_variants": {} }, { "sku": "NKX50-Z", "brand": "SKF", "manufacturer_designation": "NKX 50 Z", "series": "NKX-series", "type": "needle", "d_mm": 50, "D_mm": 62, "B_mm": 35, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 38, "static_load_kN": 78, "fatigue_load_limit_kN": 9.65, "max_rpm": 3600, "reference_speed_rpm": 4300, "limiting_speed_rpm": 3600, "weight_g": 300, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "The combined needle roller / thrust ball bearings with caged thrust part execution NKX 50 Z measures 50×62×35 mm and carries radial load 38 kN dynamic plus one-direction axial load 28.6 kN (Ca) — the caged thrust part runs at higher speed than full complement NX types. In SKF nomenclature NKX is the combined family: the number states 50 mm, and unlike NX the thrust balls are caged, trading some axial capacity for speed and friction. Execution notes: the Z suffix adds a shield over the thrust balls, TN a polymer cage; the open execution allows relubrication through the shaft, the Z execution is greased for life. Selection arithmetic for the combined unit: radial C 38 kN, radial C0 78 kN, axial dynamic 28.6 kN (Ca) and axial static 81.5 kN (C0a); combine them with the equivalent-load factors from the catalogue before checking L10. The caged thrust part survives moderate speed only with the Z shield intact — damaged shields admit grit straight into the ball raceways, and the narrow section leaves no margin.", "applications": [ "conveyor screw thrust ends", "turntable and swivel mounts", "machine tool feed spindles with one-direction thrust", "pump impeller shafts with steady axial pull" ], "failure_modes": [ "needle edge loading and raceway denting when the shaft deflects beyond the compensation range", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "brinelling of raceways from impact or pressing force transmitted through the rolling elements", "thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry" ], "pitfalls": [ "At 50 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 50 mm seats can bend past the compensation range long before the load rating is exhausted.", "Contamination, not fatigue, kills most small needle bearings: with raceways this narrow, one hard particle dents a full-width line — seal the housing even when the bearing execution itself is open.", "Do not interchange envelope-identical needle families blindly: NKX 50 Z shares its 50×62×35 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKX 50 Z facing the working thrust.", "Minimum axial load is a real requirement: below factor A 0.034 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "The 38/78 kN ratings and 300 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "What mounting mistakes ruin a NKX 50 Z?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 50 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "Is the NKX 50 Z sealed?", "a": "No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty." }, { "q": "Which dimensions does the NKX 50 Z have?", "a": "A NKX 50 Z measures 50 mm bore/Fw × 62 mm outside diameter × 35 mm width (1.969 × 2.441 × 1.378 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 38 kN, static C0 78 kN, fatigue limit Pu 9.65 kN, limiting speed 3,600 r/min, reference speed 4,300 r/min, mass about 300 g. Axial ratings of the thrust part: dynamic Ca 28.6 kN (Ca), static C0a 81.5 kN (C0a), minimum load factor A 0.034; the thrust set carries load in one direction only." }, { "q": "What does NKX 50 Z mean in SKF part numbering?", "a": "NKX = needle roller radial part + caged thrust ball part for a 50 mm shaft: 62 mm OD, 35 mm overall height. The caged thrust part trades some axial capacity for higher permissible speed versus NX." } ], "cross_ref": [ { "equiv_sku": "NKX50", "equiv_brand": "SKF", "level": "full", "note": "Same 50×62×35 mm envelope and equivalent catalogue ratings; NKX50 is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NK50-35-TN", "equiv_brand": "SKF", "level": "partial", "note": "Same 50×62×35 mm envelope, but catalogue C/C0 differ between the executions (38/78 vs 58.3/137 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NKXR50", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (50×62×35 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR50-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (50×62×35 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX50-Z", "NKX 50 Z" ], "locale_variants": {} }, { "sku": "NKX50", "brand": "SKF", "manufacturer_designation": "NKX 50", "series": "NKX-series", "type": "needle", "d_mm": 50, "D_mm": 62, "B_mm": 35, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 38, "static_load_kN": 78, "fatigue_load_limit_kN": 9.65, "max_rpm": 6300, "reference_speed_rpm": 4300, "limiting_speed_rpm": 6300, "weight_g": 280, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "In SKF catalogue PUB BU/P1 17000, NKX 50 designates a combined bearing with needle roller radial part and caged thrust ball part: 50 mm shaft seat, 62 mm OD, thrust dynamic rating 28.6 kN (Ca). In SKF nomenclature NKX is the combined family: the number states 50 mm, and unlike NX the thrust balls are caged, trading some axial capacity for speed and friction. Caged thrust balls allow higher speeds than the full complement NX execution in the same envelope; the trade-off is a somewhat lower axial rating — compare the Ca figures before choosing. Axial capability is one-direction: size the arrangement so working thrust pushes the thrust-washer face, and provide a mirrored unit or separate bearing for load reversals. Mounting: press the unit onto the 50 mm seat against the inner faces, orient the thrust set toward the axial load, and verify the 35 mm overall height against the housing stack after fitting.", "applications": [ "turntable and swivel mounts", "machine tool feed spindles with one-direction thrust", "pump impeller shafts with steady axial pull", "gear pairs generating one-direction axial force" ], "failure_modes": [ "needle edge loading and raceway denting when the shaft deflects beyond the compensation range", "cage pocket wear and roller skew after sustained operation with too little radial preload", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "rolling-contact fatigue spalling after the rated L10 life", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "At 50 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 50 mm seats can bend past the compensation range long before the load rating is exhausted.", "The quoted 38/78 kN ratings are SKF catalogue values for this exact execution (NKX 50); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.", "Oscillating pivots fail differently: rocking through a small angle concentrates wear in the same roller positions — inspect those zones, and consider rotating the assembly's clock position at service intervals.", "Do not treat the axial rating 28.6 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKX 50 facing the working thrust.", "The 38/78 kN ratings and 280 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "Is the NKX 50 sealed?", "a": "No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty." }, { "q": "Which dimensions does the NKX 50 have?", "a": "A NKX 50 measures 50 mm bore/Fw × 62 mm outside diameter × 35 mm width (1.969 × 2.441 × 1.378 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 38 kN, static C0 78 kN, fatigue limit Pu 9.65 kN, limiting speed 6,300 r/min, reference speed 4,300 r/min, mass about 280 g. Axial ratings of the thrust part: dynamic Ca 28.6 kN (Ca), static C0a 81.5 kN (C0a), minimum load factor A 0.034; the thrust set carries load in one direction only." }, { "q": "What does NKX 50 mean in SKF part numbering?", "a": "NKX = needle roller radial part + caged thrust ball part for a 50 mm shaft: 62 mm OD, 35 mm overall height. The caged thrust part trades some axial capacity for higher permissible speed versus NX." }, { "q": "Does the NKX 50 need a hardened and ground shaft?", "a": "The radial needle part of the NKX 50 runs directly on the 50 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." } ], "cross_ref": [ { "equiv_sku": "NKX50-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 50×62×35 mm envelope and equivalent catalogue ratings; NKX50-Z is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NK50-35-TN", "equiv_brand": "SKF", "level": "partial", "note": "Same 50×62×35 mm envelope, but catalogue C/C0 differ between the executions (38/78 vs 58.3/137 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NKXR50", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (50×62×35 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKXR50-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (50×62×35 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX50", "NKX 50" ], "locale_variants": {} }, { "sku": "NKX60-Z", "brand": "SKF", "manufacturer_designation": "NKX 60 Z", "series": "NKX-series", "type": "needle", "d_mm": 60, "D_mm": 72, "B_mm": 40, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 41.8, "static_load_kN": 96.5, "fatigue_load_limit_kN": 11.8, "max_rpm": 3000, "reference_speed_rpm": 3600, "limiting_speed_rpm": 3000, "weight_g": 380, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "NKX 60 Z is a combined needle roller / thrust ball bearing with a caged thrust part: radial load on caged needle rollers, axial load on a ball thrust set with stamped cages, per SKF catalogue PUB BU/P1 17000 ch. 7.9. In SKF nomenclature NKX is the combined family: the number states 60 mm, and unlike NX the thrust balls are caged, trading some axial capacity for speed and friction. The thrust part takes axial load in one direction only; mount it facing the working load and provide a separate locating bearing for reverse events. Axial capability is one-direction: size the arrangement so working thrust pushes the thrust-washer face, and provide a mirrored unit or separate bearing for load reversals. Apply the working axial load after mounting and re-check running torque; a rising torque in the first minutes signals balls climbing the washer lip under reversed thrust.", "applications": [ "rotary indexing tables under combined load", "conveyor screw thrust ends", "turntable and swivel mounts", "machine tool feed spindles with one-direction thrust" ], "failure_modes": [ "needle edge loading and raceway denting when the shaft deflects beyond the compensation range", "cage pocket wear and roller skew after sustained operation with too little radial preload", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "electrical erosion on VFD-driven shafts without brush or insulated mounting", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "Above 50 mm bore, thermal growth matters: the 60 mm inner ring or journal grows with temperature faster than the housing, and the small clearance of a needle roller contact leaves little reserve — check running clearance hot, not just at assembly.", "Reference and limiting speeds are different limits: the 3,600 r/min reference is the thermal criterion under load, The limiting value is mechanical; the reference value is thermal under load, and grease choice moves it substantially.", "Hardness is load capacity: in families without an inner ring the 60 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.", "Do not treat the axial rating 41.6 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKX 60 Z facing the working thrust.", "The 41.8/96.5 kN ratings and 380 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "Does the NKX 60 Z need a hardened and ground shaft?", "a": "The radial needle part of the NKX 60 Z runs directly on the 60 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "What mounting mistakes ruin a NKX 60 Z?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 60 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "Is the NKX 60 Z sealed?", "a": "No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty." }, { "q": "Which dimensions does the NKX 60 Z have?", "a": "A NKX 60 Z measures 60 mm bore/Fw × 72 mm outside diameter × 40 mm width (2.362 × 2.835 × 1.575 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 41.8 kN, static C0 96.5 kN, fatigue limit Pu 11.8 kN, limiting speed 3,000 r/min, reference speed 3,600 r/min, mass about 380 g. Axial ratings of the thrust part: dynamic Ca 41.6 kN (Ca), static C0a 122 kN (C0a), minimum load factor A 0.077; the thrust set carries load in one direction only." } ], "cross_ref": [ { "equiv_sku": "NKX60", "equiv_brand": "SKF", "level": "full", "note": "Same 60×72×40 mm envelope and equivalent catalogue ratings; NKX60 is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX60-Z", "NKX 60 Z" ], "locale_variants": {} }, { "sku": "NKX60", "brand": "SKF", "manufacturer_designation": "NKX 60", "series": "NKX-series", "type": "needle", "d_mm": 60, "D_mm": 72, "B_mm": 40, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 41.8, "static_load_kN": 96.5, "fatigue_load_limit_kN": 11.8, "max_rpm": 5000, "reference_speed_rpm": 3600, "limiting_speed_rpm": 5000, "weight_g": 360, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "For a 60 mm shaft under radial plus one-direction axial load, NKX 60 from the combined needle roller / thrust ball bearings with caged thrust part provides both in 72×40 mm: needle roller cage below, caged thrust ball set above. The code NKX 60 reads as combined radial/thrust for a 60 mm shaft; the catalogue height 40 mm stacks the radial cage and the thrust set, and the 72 mm OD seats both parts in one bore. Execution notes: the Z suffix adds a shield over the thrust balls, TN a polymer cage; the open execution allows relubrication through the shaft, the Z execution is greased for life. The minimum load factor A 0.077 applies to the thrust part: below that axial load the rolling elements of the thrust set skid, so springs or preload washers are part of the arrangement, not an afterthought. Apply the working axial load after mounting and re-check running torque; a rising torque in the first minutes signals balls climbing the washer lip under reversed thrust.", "applications": [ "turntable and swivel mounts", "machine tool feed spindles with one-direction thrust", "pump impeller shafts with steady axial pull", "gear pairs generating one-direction axial force" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "hard-particle indentation in unfiltered lubricant", "thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry" ], "pitfalls": [ "Above 50 mm bore, thermal growth matters: the 60 mm inner ring or journal grows with temperature faster than the housing, and the small clearance of a needle roller contact leaves little reserve — check running clearance hot, not just at assembly.", "Oscillating pivots fail differently: rocking through a small angle concentrates wear in the same roller positions — inspect those zones, and consider rotating the assembly's clock position at service intervals.", "Contamination, not fatigue, kills most small needle bearings: with raceways this narrow, one hard particle dents a full-width line — seal the housing even when the bearing execution itself is open.", "Height stack-up is easy to mis-check: the thrust-washer part adds height beyond a plain needle bearing, and clamping the stack solid over it preloads the thrust set beyond its rating.", "Do not treat the axial rating 41.6 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.", "The 41.8/96.5 kN ratings and 360 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "How is the NKX 60 designation read?", "a": "NKX = needle roller radial part + caged thrust ball part for a 60 mm shaft: 72 mm OD, 40 mm overall height. The caged thrust part trades some axial capacity for higher permissible speed versus NX." }, { "q": "Can the NKX 60 run on an unhardened shaft?", "a": "The radial needle part of the NKX 60 runs directly on the 60 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "How should the NKX 60 be mounted?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 60 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "What limits the service life of a NKX 60?", "a": "Beyond the L10 rating, the practical limits are journal/raceway hardness for the 60 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 6.0 mm radial section leaves no reserve once a raceway is dented or ribboned." } ], "cross_ref": [ { "equiv_sku": "NKX60-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 60×72×40 mm envelope and equivalent catalogue ratings; NKX60-Z is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX60", "NKX 60" ], "locale_variants": {} }, { "sku": "NKX70-Z", "brand": "SKF", "manufacturer_designation": "NKX 70 Z", "series": "NKX-series", "type": "needle", "d_mm": 70, "D_mm": 85, "B_mm": 40, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 44.6, "static_load_kN": 98, "fatigue_load_limit_kN": 12.2, "max_rpm": 2700, "reference_speed_rpm": 3400, "limiting_speed_rpm": 2700, "weight_g": 520, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "NKX 70 Z is a combined needle roller / thrust ball bearing with a caged thrust part: radial load on caged needle rollers, axial load on a ball thrust set with stamped cages, per SKF catalogue PUB BU/P1 17000 ch. 7.9. The code NKX 70 Z reads as combined radial/thrust for a 70 mm shaft; the catalogue height 40 mm stacks the radial cage and the thrust set, and the 85 mm OD seats both parts in one bore. Execution notes: the Z suffix adds a shield over the thrust balls, TN a polymer cage; the open execution allows relubrication through the shaft, the Z execution is greased for life. Speed ceilings differ by part: 3,400 r/min thermal reference and 2,700 r/min limiting — the thrust element governs, since its washer faces see sliding components of contact. Mounting: press the unit onto the 70 mm seat against the inner faces, orient the thrust set toward the axial load, and verify the 40 mm overall height against the housing stack after fitting.", "applications": [ "gear pairs generating one-direction axial force", "rotary indexing tables under combined load", "conveyor screw thrust ends", "turntable and swivel mounts" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "cage pocket wear and roller skew after sustained operation with too little radial preload", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "rolling-contact fatigue spalling after the rated L10 life", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "Above 50 mm bore, thermal growth matters: the 70 mm inner ring or journal grows with temperature faster than the housing, and the small clearance of a needle roller contact leaves little reserve — check running clearance hot, not just at assembly.", "Hardness is load capacity: in families without an inner ring the 70 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.", "The quoted 44.6/98 kN ratings are SKF catalogue values for this exact execution (NKX 70 Z); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.", "Do not treat the axial rating 43.6 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKX 70 Z facing the working thrust.", "The 44.6/98 kN ratings and 520 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "Can the NKX 70 Z run on an unhardened shaft?", "a": "The radial needle part of the NKX 70 Z runs directly on the 70 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "How should the NKX 70 Z be mounted?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 70 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "What limits the service life of a NKX 70 Z?", "a": "Beyond the L10 rating, the practical limits are journal/raceway hardness for the 70 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 7.5 mm radial section leaves no reserve once a raceway is dented or ribboned." }, { "q": "What are the dimensions and ratings of the NKX 70 Z?", "a": "A NKX 70 Z measures 70 mm bore/Fw × 85 mm outside diameter × 40 mm width (2.756 × 3.346 × 1.575 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 44.6 kN, static C0 98 kN, fatigue limit Pu 12.2 kN, limiting speed 2,700 r/min, reference speed 3,400 r/min, mass about 520 g. Axial ratings of the thrust part: dynamic Ca 43.6 kN (Ca), static C0a 137 kN (C0a), minimum load factor A 0.097; the thrust set carries load in one direction only." } ], "cross_ref": [ { "equiv_sku": "NKX70", "equiv_brand": "SKF", "level": "full", "note": "Same 70×85×40 mm envelope and equivalent catalogue ratings; NKX70 is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX70-Z", "NKX 70 Z" ], "locale_variants": {} }, { "sku": "NKX70", "brand": "SKF", "manufacturer_designation": "NKX 70", "series": "NKX-series", "type": "needle", "d_mm": 70, "D_mm": 85, "B_mm": 40, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 44.6, "static_load_kN": 98, "fatigue_load_limit_kN": 12.2, "max_rpm": 4500, "reference_speed_rpm": 3400, "limiting_speed_rpm": 4500, "weight_g": 500, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "In SKF catalogue PUB BU/P1 17000, NKX 70 designates a combined bearing with needle roller radial part and caged thrust ball part: 70 mm shaft seat, 85 mm OD, thrust dynamic rating 43.6 kN (Ca). Reading the designation: NKX marks needle roller + caged thrust ball, the number the 70 mm shaft seat; the 85 mm OD and 40 mm overall height come from the series plan. The thrust part takes axial load in one direction only; mount it facing the working load and provide a separate locating bearing for reverse events. Axial capability is one-direction: size the arrangement so working thrust pushes the thrust-washer face, and provide a mirrored unit or separate bearing for load reversals. The caged thrust part survives moderate speed only with the Z shield intact — damaged shields admit grit straight into the ball raceways, and the narrow section leaves no margin.", "applications": [ "turntable and swivel mounts", "machine tool feed spindles with one-direction thrust", "pump impeller shafts with steady axial pull", "gear pairs generating one-direction axial force" ], "failure_modes": [ "needle edge loading and raceway denting when the shaft deflects beyond the compensation range", "cage pocket wear and roller skew after sustained operation with too little radial preload", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "false brinelling of standby equipment under external vibration", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "Above 50 mm bore, thermal growth matters: the 70 mm inner ring or journal grows with temperature faster than the housing, and the small clearance of a needle roller contact leaves little reserve — check running clearance hot, not just at assembly.", "Contamination, not fatigue, kills most small needle bearings: with raceways this narrow, one hard particle dents a full-width line — seal the housing even when the bearing execution itself is open.", "Do not interchange envelope-identical needle families blindly: NKX 70 shares its 70×85×40 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.", "Minimum axial load is a real requirement: below factor A 0.097 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "Height stack-up is easy to mis-check: the thrust-washer part adds height beyond a plain needle bearing, and clamping the stack solid over it preloads the thrust set beyond its rating.", "The 44.6/98 kN ratings and 500 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "What mounting mistakes ruin a NKX 70?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 70 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "Is the NKX 70 sealed?", "a": "No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty." }, { "q": "Which dimensions does the NKX 70 have?", "a": "A NKX 70 measures 70 mm bore/Fw × 85 mm outside diameter × 40 mm width (2.756 × 3.346 × 1.575 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 44.6 kN, static C0 98 kN, fatigue limit Pu 12.2 kN, limiting speed 4,500 r/min, reference speed 3,400 r/min, mass about 500 g. Axial ratings of the thrust part: dynamic Ca 43.6 kN (Ca), static C0a 137 kN (C0a), minimum load factor A 0.097; the thrust set carries load in one direction only." }, { "q": "What does NKX 70 mean in SKF part numbering?", "a": "NKX = needle roller radial part + caged thrust ball part for a 70 mm shaft: 85 mm OD, 40 mm overall height. The caged thrust part trades some axial capacity for higher permissible speed versus NX." } ], "cross_ref": [ { "equiv_sku": "NKX70-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 70×85×40 mm envelope and equivalent catalogue ratings; NKX70-Z is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKX70", "NKX 70" ], "locale_variants": {} }, { "sku": "NKXR15", "brand": "SKF", "manufacturer_designation": "NKXR 15", "series": "NKXR-series", "type": "needle", "d_mm": 15, "D_mm": 24, "B_mm": 23, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 11, "static_load_kN": 14, "fatigue_load_limit_kN": 1.66, "max_rpm": 8500, "reference_speed_rpm": 4300, "limiting_speed_rpm": 8500, "weight_g": 42, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "NKXR 15 is the heavy-thrust member of the combined needle roller family: 15 mm radial seat, 24 mm OD, and a full complement of thrust needles rated 11.2 kN (Ca) dynamic / 27 kN (C0a) static. The R before the X in NKXR flags the roller (not ball) thrust part; the figure gives the 15 mm seat, and the catalogue completes 24×23 mm. Thrust needle sets tolerate slow speeds and heavy loads: the 8,500 r/min limiting speed is far below ball-thrust equivalents, and lubricant film at the washer faces governs life. Selection arithmetic for the combined unit: radial C 11 kN, radial C0 14 kN, axial dynamic 11.2 kN (Ca) and axial static 27 kN (C0a); combine them with the equivalent-load factors from the catalogue before checking L10. Fit with a press against the washer faces only — needles packed without a cage will skew if the assembly is dropped or driven sideways onto the 15 mm seat.", "applications": [ "turntables and slewing pivots with shock loads", "press-fit die set guide positions", "heavy screw presses and clamping spindles", "crane slew rings and kingposts at low speed" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "cage pocket wear and roller skew after sustained operation with too little radial preload", "abrasive paste formation from dust ingressing past open ends without effective housing seals", "false brinelling of standby equipment under external vibration", "thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry" ], "pitfalls": [ "On a 15 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 24 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.", "Do not interchange envelope-identical needle families blindly: NKXR 15 shares its 15×24×23 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.", "Reference and limiting speeds are different limits: the 4,300 r/min reference is the thermal criterion under load, The limiting value is mechanical; the reference value is thermal under load, and grease choice moves it substantially.", "Do not treat the axial rating 11.2 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKXR 15 facing the working thrust.", "The 11/14 kN ratings and 42 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "How is the NKXR 15 designation read?", "a": "NKXR = needle roller radial part + full complement needle thrust part for a 15 mm shaft: 24 mm OD, 23 mm overall height, the highest axial rating of the combined needle families." }, { "q": "Can the NKXR 15 run on an unhardened shaft?", "a": "The radial needle part of the NKXR 15 runs directly on the 15 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "How should the NKXR 15 be mounted?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 15 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "What limits the service life of a NKXR 15?", "a": "Beyond the L10 rating, the practical limits are journal/raceway hardness for the 15 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 4.5 mm radial section leaves no reserve once a raceway is dented or ribboned." } ], "cross_ref": [ { "equiv_sku": "NKXR15-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 15×24×23 mm envelope and equivalent catalogue ratings; NKXR15-Z is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NKX15-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (15×24×23 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX15", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (15×24×23 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKXR15", "NKXR 15" ], "locale_variants": {} }, { "sku": "NKXR15-Z", "brand": "SKF", "manufacturer_designation": "NKXR 15 Z", "series": "NKXR-series", "type": "needle", "d_mm": 15, "D_mm": 24, "B_mm": 23, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 11, "static_load_kN": 14, "fatigue_load_limit_kN": 1.66, "max_rpm": 8500, "reference_speed_rpm": 4300, "limiting_speed_rpm": 8500, "weight_g": 45, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "In SKF catalogue PUB BU/P1 17000, NKXR 15 Z denotes a combined bearing with needle roller radial part and full complement thrust needle part for one-direction axial loads at slow to moderate speed. In SKF nomenclature NKXR is the highest-capacity combined family: 15 mm shaft seat, packed thrust needles above the radial cage, axial rating 11.2 kN (Ca) dynamic. Execution notes: the Z suffix shields the thrust needle set; the full complement part delivers the highest axial rating in the family but needs the minimum axial load (factor A 0.000058) to prevent needle skidding. Axial capability is one-direction: size the arrangement so working thrust pushes the thrust-washer face, and provide a mirrored unit or separate bearing for load reversals. These units run at low speed with high axial load: verify lubricant channeling at the washer faces after the first hour, as the packed thrust set pumps grease axially out of the 23 mm tall envelope.", "applications": [ "press-fit die set guide positions", "heavy screw presses and clamping spindles", "crane slew rings and kingposts at low speed", "extruder and mixer thrust positions" ], "failure_modes": [ "needle edge loading and raceway denting when the shaft deflects beyond the compensation range", "cage pocket wear and roller skew after sustained operation with too little radial preload", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "electrical erosion on VFD-driven shafts without brush or insulated mounting", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "On a 15 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 24 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.", "Reference and limiting speeds are different limits: the 4,300 r/min reference is the thermal criterion under load, The limiting value is mechanical; the reference value is thermal under load, and grease choice moves it substantially.", "Hardness is load capacity: in families without an inner ring the 15 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.", "Do not treat the axial rating 11.2 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKXR 15 Z facing the working thrust.", "The 11/14 kN ratings and 45 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "What does NKXR 15 Z mean in SKF part numbering?", "a": "NKXR = needle roller radial part + full complement needle thrust part for a 15 mm shaft: 24 mm OD, 23 mm overall height, the highest axial rating of the combined needle families." }, { "q": "Does the NKXR 15 Z need a hardened and ground shaft?", "a": "The radial needle part of the NKXR 15 Z runs directly on the 15 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "What mounting mistakes ruin a NKXR 15 Z?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 15 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "Is the NKXR 15 Z sealed?", "a": "No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty." } ], "cross_ref": [ { "equiv_sku": "NKXR15", "equiv_brand": "SKF", "level": "full", "note": "Same 15×24×23 mm envelope and equivalent catalogue ratings; NKXR15 is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NKX15-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (15×24×23 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX15", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (15×24×23 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKXR15-Z", "NKXR 15 Z" ], "locale_variants": {} }, { "sku": "NKXR17", "brand": "SKF", "manufacturer_designation": "NKXR 17", "series": "NKXR-series", "type": "needle", "d_mm": 17, "D_mm": 26, "B_mm": 25, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 12.1, "static_load_kN": 16.6, "fatigue_load_limit_kN": 1.96, "max_rpm": 8500, "reference_speed_rpm": 4300, "limiting_speed_rpm": 8500, "weight_g": 50, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "For a 17 mm shaft under strong one-direction axial load with limited radial space, NKXR 17 from the combined needle roller / full complement needle thrust bearings stacks a caged needle radial part with a full complement thrust needle part: 17×26×25 mm. The code NKXR 17 identifies the construction exactly — needle radial part, needle thrust part — for a 17 mm shaft; the thrust set is one-directional and must face the working axial load. One-direction thrust only — reverse axial loads lift the packed needle set off its raceway; arrange a second unit mirrored or a separate thrust bearing for reversing duty. Selection arithmetic for the combined unit: radial C 12.1 kN, radial C0 16.6 kN, axial dynamic 12.2 kN (Ca) and axial static 31.5 kN (C0a); combine them with the equivalent-load factors from the catalogue before checking L10. Fit with a press against the washer faces only — needles packed without a cage will skew if the assembly is dropped or driven sideways onto the 17 mm seat.", "applications": [ "turntables and slewing pivots with shock loads", "press-fit die set guide positions", "heavy screw presses and clamping spindles", "crane slew rings and kingposts at low speed" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "cage pocket wear and roller skew after sustained operation with too little radial preload", "abrasive paste formation from dust ingressing past open ends without effective housing seals", "false brinelling of standby equipment under external vibration", "thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry" ], "pitfalls": [ "On a 17 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 26 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.", "Oscillating pivots fail differently: rocking through a small angle concentrates wear in the same roller positions — inspect those zones, and consider rotating the assembly's clock position at service intervals.", "Contamination, not fatigue, kills most small needle bearings: with raceways this narrow, one hard particle dents a full-width line — seal the housing even when the bearing execution itself is open.", "Minimum axial load is a real requirement: below factor A 0.000079 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "Height stack-up is easy to mis-check: the thrust-washer part adds height beyond a plain needle bearing, and clamping the stack solid over it preloads the thrust set beyond its rating.", "The 12.1/16.6 kN ratings and 50 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "What limits the service life of a NKXR 17?", "a": "Beyond the L10 rating, the practical limits are journal/raceway hardness for the 17 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 4.5 mm radial section leaves no reserve once a raceway is dented or ribboned." }, { "q": "What are the dimensions and ratings of the NKXR 17?", "a": "A NKXR 17 measures 17 mm bore/Fw × 26 mm outside diameter × 25 mm width (0.669 × 1.024 × 0.984 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 12.1 kN, static C0 16.6 kN, fatigue limit Pu 1.96 kN, limiting speed 8,500 r/min, reference speed 4,300 r/min, mass about 50 g. Axial ratings of the thrust part: dynamic Ca 12.2 kN (Ca), static C0a 31.5 kN (C0a), minimum load factor A 0.000079; the thrust set carries load in one direction only." }, { "q": "How is the NKXR 17 designation read?", "a": "NKXR = needle roller radial part + full complement needle thrust part for a 17 mm shaft: 26 mm OD, 25 mm overall height, the highest axial rating of the combined needle families." }, { "q": "Can the NKXR 17 run on an unhardened shaft?", "a": "The radial needle part of the NKXR 17 runs directly on the 17 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." } ], "cross_ref": [ { "equiv_sku": "NKXR17-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 17×26×25 mm envelope and equivalent catalogue ratings; NKXR17-Z is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NKX17-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (17×26×25 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX17", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (17×26×25 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKXR17", "NKXR 17" ], "locale_variants": {} }, { "sku": "NKXR17-Z", "brand": "SKF", "manufacturer_designation": "NKXR 17 Z", "series": "NKXR-series", "type": "needle", "d_mm": 17, "D_mm": 26, "B_mm": 25, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 12.1, "static_load_kN": 16.6, "fatigue_load_limit_kN": 1.96, "max_rpm": 8500, "reference_speed_rpm": 4300, "limiting_speed_rpm": 8500, "weight_g": 53, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "In SKF catalogue PUB BU/P1 17000, NKXR 17 Z denotes a combined bearing with needle roller radial part and full complement thrust needle part for one-direction axial loads at slow to moderate speed. The R before the X in NKXR flags the roller (not ball) thrust part; the figure gives the 17 mm seat, and the catalogue completes 26×25 mm. Thrust needle sets tolerate slow speeds and heavy loads: the 8,500 r/min limiting speed is far below ball-thrust equivalents, and lubricant film at the washer faces governs life. The minimum load factor A 0.000079 applies to the thrust part: below that axial load the rolling elements of the thrust set skid, so springs or preload washers are part of the arrangement, not an afterthought. Mounting: the thrust needle complement is held by grease during assembly; fill the washer set, orient toward the axial load, and preload to at least factor A 0.000079 before rotating.", "applications": [ "large valve stems under high axial load", "turntables and slewing pivots with shock loads", "press-fit die set guide positions", "heavy screw presses and clamping spindles" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "abrasive paste formation from dust ingressing past open ends without effective housing seals", "corrosion pitting from condensation in intermittently operated machinery", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "On a 17 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 26 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.", "Oscillating pivots fail differently: rocking through a small angle concentrates wear in the same roller positions — inspect those zones, and consider rotating the assembly's clock position at service intervals.", "Contamination, not fatigue, kills most small needle bearings: with raceways this narrow, one hard particle dents a full-width line — seal the housing even when the bearing execution itself is open.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKXR 17 Z facing the working thrust.", "Minimum axial load is a real requirement: below factor A 0.000079 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "The 12.1/16.6 kN ratings and 53 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "Can the NKXR 17 Z run on an unhardened shaft?", "a": "The radial needle part of the NKXR 17 Z runs directly on the 17 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "How should the NKXR 17 Z be mounted?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 17 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "What limits the service life of a NKXR 17 Z?", "a": "Beyond the L10 rating, the practical limits are journal/raceway hardness for the 17 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 4.5 mm radial section leaves no reserve once a raceway is dented or ribboned." }, { "q": "What are the dimensions and ratings of the NKXR 17 Z?", "a": "A NKXR 17 Z measures 17 mm bore/Fw × 26 mm outside diameter × 25 mm width (0.669 × 1.024 × 0.984 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 12.1 kN, static C0 16.6 kN, fatigue limit Pu 1.96 kN, limiting speed 8,500 r/min, reference speed 4,300 r/min, mass about 53 g. Axial ratings of the thrust part: dynamic Ca 12.2 kN (Ca), static C0a 31.5 kN (C0a), minimum load factor A 0.000079; the thrust set carries load in one direction only." } ], "cross_ref": [ { "equiv_sku": "NKXR17", "equiv_brand": "SKF", "level": "full", "note": "Same 17×26×25 mm envelope and equivalent catalogue ratings; NKXR17 is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NKX17-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (17×26×25 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX17", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (17×26×25 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKXR17-Z", "NKXR 17 Z" ], "locale_variants": {} }, { "sku": "NKXR20", "brand": "SKF", "manufacturer_designation": "NKXR 20", "series": "NKXR-series", "type": "needle", "d_mm": 20, "D_mm": 30, "B_mm": 30, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 16.5, "static_load_kN": 25.5, "fatigue_load_limit_kN": 3.05, "max_rpm": 7500, "reference_speed_rpm": 3800, "limiting_speed_rpm": 7500, "weight_g": 80, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "The combined needle roller / full complement needle thrust bearings execution NKXR 20 measures 20×30×30 mm: radial dynamic 16.5 kN, axial dynamic 18.6 kN (Ca) — the thrust needle complement gives roughly twice the axial rating of a same-size thrust ball part. The R before the X in NKXR flags the roller (not ball) thrust part; the figure gives the 20 mm seat, and the catalogue completes 30×30 mm. One-direction thrust only — reverse axial loads lift the packed needle set off its raceway; arrange a second unit mirrored or a separate thrust bearing for reversing duty. Selection arithmetic for the combined unit: radial C 16.5 kN, radial C0 25.5 kN, axial dynamic 18.6 kN (Ca) and axial static 48 kN (C0a); combine them with the equivalent-load factors from the catalogue before checking L10. Mounting: the thrust needle complement is held by grease during assembly; fill the washer set, orient toward the axial load, and preload to at least factor A 0.00018 before rotating.", "applications": [ "turntables and slewing pivots with shock loads", "press-fit die set guide positions", "heavy screw presses and clamping spindles", "crane slew rings and kingposts at low speed" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "cage pocket wear and roller skew after sustained operation with too little radial preload", "abrasive paste formation from dust ingressing past open ends without effective housing seals", "rolling-contact fatigue spalling after the rated L10 life", "thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry" ], "pitfalls": [ "On a 20 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 30 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.", "Do not interchange envelope-identical needle families blindly: NKXR 20 shares its 20×30×30 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.", "Reference and limiting speeds are different limits: the 3,800 r/min reference is the thermal criterion under load, The limiting value is mechanical; the reference value is thermal under load, and grease choice moves it substantially.", "Do not treat the axial rating 18.6 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKXR 20 facing the working thrust.", "The 16.5/25.5 kN ratings and 80 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "How should the NKXR 20 be mounted?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 20 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "What limits the service life of a NKXR 20?", "a": "Beyond the L10 rating, the practical limits are journal/raceway hardness for the 20 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 5.0 mm radial section leaves no reserve once a raceway is dented or ribboned." }, { "q": "What are the dimensions and ratings of the NKXR 20?", "a": "A NKXR 20 measures 20 mm bore/Fw × 30 mm outside diameter × 30 mm width (0.787 × 1.181 × 1.181 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 16.5 kN, static C0 25.5 kN, fatigue limit Pu 3.05 kN, limiting speed 7,500 r/min, reference speed 3,800 r/min, mass about 80 g. Axial ratings of the thrust part: dynamic Ca 18.6 kN (Ca), static C0a 48 kN (C0a), minimum load factor A 0.00018; the thrust set carries load in one direction only." }, { "q": "How is the NKXR 20 designation read?", "a": "NKXR = needle roller radial part + full complement needle thrust part for a 20 mm shaft: 30 mm OD, 30 mm overall height, the highest axial rating of the combined needle families." } ], "cross_ref": [ { "equiv_sku": "NKXR20-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 20×30×30 mm envelope and equivalent catalogue ratings; NKXR20-Z is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NKX20-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (20×30×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX20", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (20×30×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKXR20", "NKXR 20" ], "locale_variants": {} }, { "sku": "NKXR20-Z", "brand": "SKF", "manufacturer_designation": "NKXR 20 Z", "series": "NKXR-series", "type": "needle", "d_mm": 20, "D_mm": 30, "B_mm": 30, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 16.5, "static_load_kN": 25.5, "fatigue_load_limit_kN": 3.05, "max_rpm": 7500, "reference_speed_rpm": 3800, "limiting_speed_rpm": 7500, "weight_g": 84, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "For a 20 mm shaft under strong one-direction axial load with limited radial space, NKXR 20 Z from the combined needle roller / full complement needle thrust bearings stacks a caged needle radial part with a full complement thrust needle part: 20×30×30 mm. Reading the designation: NKXR marks needle roller + full complement needle thrust, the number the 20 mm shaft seat; 30 mm OD and 30 mm height follow the series plan. Execution notes: the Z suffix shields the thrust needle set; the full complement part delivers the highest axial rating in the family but needs the minimum axial load (factor A 0.00018) to prevent needle skidding. Speed ceilings differ by part: 3,800 r/min thermal reference and 7,500 r/min limiting — the thrust element governs, since its washer faces see sliding components of contact. These units run at low speed with high axial load: verify lubricant channeling at the washer faces after the first hour, as the packed thrust set pumps grease axially out of the 30 mm tall envelope.", "applications": [ "turntables and slewing pivots with shock loads", "press-fit die set guide positions", "heavy screw presses and clamping spindles", "crane slew rings and kingposts at low speed" ], "failure_modes": [ "needle edge loading and raceway denting when the shaft deflects beyond the compensation range", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "hard-particle indentation in unfiltered lubricant", "thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry" ], "pitfalls": [ "On a 20 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 30 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.", "The quoted 16.5/25.5 kN ratings are SKF catalogue values for this exact execution (NKXR 20 Z); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.", "Oscillating pivots fail differently: rocking through a small angle concentrates wear in the same roller positions — inspect those zones, and consider rotating the assembly's clock position at service intervals.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKXR 20 Z facing the working thrust.", "Minimum axial load is a real requirement: below factor A 0.00018 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "The 16.5/25.5 kN ratings and 84 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "Which dimensions does the NKXR 20 Z have?", "a": "A NKXR 20 Z measures 20 mm bore/Fw × 30 mm outside diameter × 30 mm width (0.787 × 1.181 × 1.181 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 16.5 kN, static C0 25.5 kN, fatigue limit Pu 3.05 kN, limiting speed 7,500 r/min, reference speed 3,800 r/min, mass about 84 g. Axial ratings of the thrust part: dynamic Ca 18.6 kN (Ca), static C0a 48 kN (C0a), minimum load factor A 0.00018; the thrust set carries load in one direction only." }, { "q": "What does NKXR 20 Z mean in SKF part numbering?", "a": "NKXR = needle roller radial part + full complement needle thrust part for a 20 mm shaft: 30 mm OD, 30 mm overall height, the highest axial rating of the combined needle families." }, { "q": "Does the NKXR 20 Z need a hardened and ground shaft?", "a": "The radial needle part of the NKXR 20 Z runs directly on the 20 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "What mounting mistakes ruin a NKXR 20 Z?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 20 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." } ], "cross_ref": [ { "equiv_sku": "NKXR20", "equiv_brand": "SKF", "level": "full", "note": "Same 20×30×30 mm envelope and equivalent catalogue ratings; NKXR20 is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NKX20-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (20×30×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX20", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (20×30×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKXR20-Z", "NKXR 20 Z" ], "locale_variants": {} }, { "sku": "NKXR25", "brand": "SKF", "manufacturer_designation": "NKXR 25", "series": "NKXR-series", "type": "needle", "d_mm": 25, "D_mm": 37, "B_mm": 30, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 19, "static_load_kN": 32.5, "fatigue_load_limit_kN": 4, "max_rpm": 6300, "reference_speed_rpm": 3200, "limiting_speed_rpm": 6300, "weight_g": 120, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "NKXR 25 is a combined needle roller / full complement needle thrust bearing: caged needle rollers for radial duty plus a packed needle thrust set for the highest axial capacity of any 25 mm combined bearing, per SKF catalogue PUB BU/P1 17000 ch. 7.10. In SKF nomenclature NKXR is the highest-capacity combined family: 25 mm shaft seat, packed thrust needles above the radial cage, axial rating 25 kN (Ca) dynamic. Execution notes: the Z suffix shields the thrust needle set; the full complement part delivers the highest axial rating in the family but needs the minimum axial load (factor A 0.00039) to prevent needle skidding. Speed ceilings differ by part: 3,200 r/min thermal reference and 6,300 r/min limiting — the thrust element governs, since its washer faces see sliding components of contact. Mounting: the thrust needle complement is held by grease during assembly; fill the washer set, orient toward the axial load, and preload to at least factor A 0.00039 before rotating.", "applications": [ "turntables and slewing pivots with shock loads", "press-fit die set guide positions", "heavy screw presses and clamping spindles", "crane slew rings and kingposts at low speed" ], "failure_modes": [ "needle edge loading and raceway denting when the shaft deflects beyond the compensation range", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "abrasive paste formation from dust ingressing past open ends without effective housing seals", "corrosion pitting from condensation in intermittently operated machinery", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "On a 25 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 37 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.", "Reference and limiting speeds are different limits: the 3,200 r/min reference is the thermal criterion under load, The limiting value is mechanical; the reference value is thermal under load, and grease choice moves it substantially.", "Hardness is load capacity: in families without an inner ring the 25 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.", "Height stack-up is easy to mis-check: the thrust-washer part adds height beyond a plain needle bearing, and clamping the stack solid over it preloads the thrust set beyond its rating.", "Do not treat the axial rating 25 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.", "The 19/32.5 kN ratings and 120 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "What mounting mistakes ruin a NKXR 25?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 25 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "Is the NKXR 25 sealed?", "a": "No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty." }, { "q": "Which dimensions does the NKXR 25 have?", "a": "A NKXR 25 measures 25 mm bore/Fw × 37 mm outside diameter × 30 mm width (0.984 × 1.457 × 1.181 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 19 kN, static C0 32.5 kN, fatigue limit Pu 4 kN, limiting speed 6,300 r/min, reference speed 3,200 r/min, mass about 120 g. Axial ratings of the thrust part: dynamic Ca 25 kN (Ca), static C0a 69.5 kN (C0a), minimum load factor A 0.00039; the thrust set carries load in one direction only." }, { "q": "What does NKXR 25 mean in SKF part numbering?", "a": "NKXR = needle roller radial part + full complement needle thrust part for a 25 mm shaft: 37 mm OD, 30 mm overall height, the highest axial rating of the combined needle families." } ], "cross_ref": [ { "equiv_sku": "NKXR25-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 25×37×30 mm envelope and equivalent catalogue ratings; NKXR25-Z is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "RNA6904", "equiv_brand": "SKF", "level": "partial", "note": "Same 25×37×30 mm envelope, but catalogue C/C0 differ between the executions (19/32.5 vs 35.2/53 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NX25-Z", "equiv_brand": "SKF", "level": "partial", "note": "Same 25×37×30 mm envelope, but catalogue C/C0 differ between the executions (19/32.5 vs 15.1/24.5 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NX25", "equiv_brand": "SKF", "level": "partial", "note": "Same 25×37×30 mm envelope, but catalogue C/C0 differ between the executions (19/32.5 vs 15.1/24.5 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NKX25-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (25×37×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX25", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (25×37×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKXR25", "NKXR 25" ], "locale_variants": {} }, { "sku": "NKXR25-Z", "brand": "SKF", "manufacturer_designation": "NKXR 25 Z", "series": "NKXR-series", "type": "needle", "d_mm": 25, "D_mm": 37, "B_mm": 30, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 19, "static_load_kN": 32.5, "fatigue_load_limit_kN": 4, "max_rpm": 6300, "reference_speed_rpm": 3200, "limiting_speed_rpm": 6300, "weight_g": 130, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "In SKF catalogue PUB BU/P1 17000, NKXR 25 Z denotes a combined bearing with needle roller radial part and full complement thrust needle part for one-direction axial loads at slow to moderate speed. The code NKXR 25 Z identifies the construction exactly — needle radial part, needle thrust part — for a 25 mm shaft; the thrust set is one-directional and must face the working axial load. Thrust needle sets tolerate slow speeds and heavy loads: the 6,300 r/min limiting speed is far below ball-thrust equivalents, and lubricant film at the washer faces governs life. Speed ceilings differ by part: 3,200 r/min thermal reference and 6,300 r/min limiting — the thrust element governs, since its washer faces see sliding components of contact. Mounting: the thrust needle complement is held by grease during assembly; fill the washer set, orient toward the axial load, and preload to at least factor A 0.00039 before rotating.", "applications": [ "turntables and slewing pivots with shock loads", "press-fit die set guide positions", "heavy screw presses and clamping spindles", "crane slew rings and kingposts at low speed" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "cage pocket wear and roller skew after sustained operation with too little radial preload", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "rolling-contact fatigue spalling after the rated L10 life", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "On a 25 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 37 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.", "Hardness is load capacity: in families without an inner ring the 25 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.", "The quoted 19/32.5 kN ratings are SKF catalogue values for this exact execution (NKXR 25 Z); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.", "Do not treat the axial rating 25 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKXR 25 Z facing the working thrust.", "The 19/32.5 kN ratings and 130 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "How is the NKXR 25 Z designation read?", "a": "NKXR = needle roller radial part + full complement needle thrust part for a 25 mm shaft: 37 mm OD, 30 mm overall height, the highest axial rating of the combined needle families." }, { "q": "Can the NKXR 25 Z run on an unhardened shaft?", "a": "The radial needle part of the NKXR 25 Z runs directly on the 25 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "How should the NKXR 25 Z be mounted?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 25 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "What limits the service life of a NKXR 25 Z?", "a": "Beyond the L10 rating, the practical limits are journal/raceway hardness for the 25 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 6.0 mm radial section leaves no reserve once a raceway is dented or ribboned." } ], "cross_ref": [ { "equiv_sku": "NKXR25", "equiv_brand": "SKF", "level": "full", "note": "Same 25×37×30 mm envelope and equivalent catalogue ratings; NKXR25 is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "RNA6904", "equiv_brand": "SKF", "level": "partial", "note": "Same 25×37×30 mm envelope, but catalogue C/C0 differ between the executions (19/32.5 vs 35.2/53 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NX25-Z", "equiv_brand": "SKF", "level": "partial", "note": "Same 25×37×30 mm envelope, but catalogue C/C0 differ between the executions (19/32.5 vs 15.1/24.5 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NX25", "equiv_brand": "SKF", "level": "partial", "note": "Same 25×37×30 mm envelope, but catalogue C/C0 differ between the executions (19/32.5 vs 15.1/24.5 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NKX25-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (25×37×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX25", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (25×37×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKXR25-Z", "NKXR 25 Z" ], "locale_variants": {} }, { "sku": "NKXR30", "brand": "SKF", "manufacturer_designation": "NKXR 30", "series": "NKXR-series", "type": "needle", "d_mm": 30, "D_mm": 42, "B_mm": 30, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 22.9, "static_load_kN": 38, "fatigue_load_limit_kN": 4.8, "max_rpm": 6000, "reference_speed_rpm": 3000, "limiting_speed_rpm": 6000, "weight_g": 140, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "SKF lists NKXR 30 where axial capacity dominates: the packed thrust needle set carries 27 kN (Ca) dynamically at the cost of speed, while the caged radial rollers contribute 22.9 kN. In SKF nomenclature NKXR is the highest-capacity combined family: 30 mm shaft seat, packed thrust needles above the radial cage, axial rating 27 kN (Ca) dynamic. Thrust needle sets tolerate slow speeds and heavy loads: the 6,000 r/min limiting speed is far below ball-thrust equivalents, and lubricant film at the washer faces governs life. Speed ceilings differ by part: 3,000 r/min thermal reference and 6,000 r/min limiting — the thrust element governs, since its washer faces see sliding components of contact. These units run at low speed with high axial load: verify lubricant channeling at the washer faces after the first hour, as the packed thrust set pumps grease axially out of the 30 mm tall envelope.", "applications": [ "turntables and slewing pivots with shock loads", "press-fit die set guide positions", "heavy screw presses and clamping spindles", "crane slew rings and kingposts at low speed" ], "failure_modes": [ "needle edge loading and raceway denting when the shaft deflects beyond the compensation range", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "abrasive paste formation from dust ingressing past open ends without effective housing seals", "hard-particle indentation in unfiltered lubricant", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "At 30 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 30 mm seats can bend past the compensation range long before the load rating is exhausted.", "Reference and limiting speeds are different limits: the 3,000 r/min reference is the thermal criterion under load, The limiting value is mechanical; the reference value is thermal under load, and grease choice moves it substantially.", "Hardness is load capacity: in families without an inner ring the 30 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.", "Height stack-up is easy to mis-check: the thrust-washer part adds height beyond a plain needle bearing, and clamping the stack solid over it preloads the thrust set beyond its rating.", "Do not treat the axial rating 27 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.", "The 22.9/38 kN ratings and 140 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "Which dimensions does the NKXR 30 have?", "a": "A NKXR 30 measures 30 mm bore/Fw × 42 mm outside diameter × 30 mm width (1.181 × 1.654 × 1.181 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 22.9 kN, static C0 38 kN, fatigue limit Pu 4.8 kN, limiting speed 6,000 r/min, reference speed 3,000 r/min, mass about 140 g. Axial ratings of the thrust part: dynamic Ca 27 kN (Ca), static C0a 78 kN (C0a), minimum load factor A 0.00049; the thrust set carries load in one direction only." }, { "q": "What does NKXR 30 mean in SKF part numbering?", "a": "NKXR = needle roller radial part + full complement needle thrust part for a 30 mm shaft: 42 mm OD, 30 mm overall height, the highest axial rating of the combined needle families." }, { "q": "Does the NKXR 30 need a hardened and ground shaft?", "a": "The radial needle part of the NKXR 30 runs directly on the 30 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "What mounting mistakes ruin a NKXR 30?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 30 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." } ], "cross_ref": [ { "equiv_sku": "NKXR30-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 30×42×30 mm envelope and equivalent catalogue ratings; NKXR30-Z is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "RNA6905", "equiv_brand": "SKF", "level": "partial", "note": "Same 30×42×30 mm envelope, but catalogue C/C0 differ between the executions (22.9/38 vs 38/62 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NX30-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (30×42×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NX30", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (30×42×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX30-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (30×42×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX30", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (30×42×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKXR30", "NKXR 30" ], "locale_variants": {} }, { "sku": "NKXR30-Z", "brand": "SKF", "manufacturer_designation": "NKXR 30 Z", "series": "NKXR-series", "type": "needle", "d_mm": 30, "D_mm": 42, "B_mm": 30, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 22.9, "static_load_kN": 38, "fatigue_load_limit_kN": 4.8, "max_rpm": 6000, "reference_speed_rpm": 3000, "limiting_speed_rpm": 6000, "weight_g": 140, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "SKF lists NKXR 30 Z where axial capacity dominates: the packed thrust needle set carries 27 kN (Ca) dynamically at the cost of speed, while the caged radial rollers contribute 22.9 kN. The R before the X in NKXR flags the roller (not ball) thrust part; the figure gives the 30 mm seat, and the catalogue completes 42×30 mm. Execution notes: the Z suffix shields the thrust needle set; the full complement part delivers the highest axial rating in the family but needs the minimum axial load (factor A 0.00049) to prevent needle skidding. The minimum load factor A 0.00049 applies to the thrust part: below that axial load the rolling elements of the thrust set skid, so springs or preload washers are part of the arrangement, not an afterthought. Fit with a press against the washer faces only — needles packed without a cage will skew if the assembly is dropped or driven sideways onto the 30 mm seat.", "applications": [ "large valve stems under high axial load", "turntables and slewing pivots with shock loads", "press-fit die set guide positions", "heavy screw presses and clamping spindles" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "abrasive paste formation from dust ingressing past open ends without effective housing seals", "brinelling of raceways from impact or pressing force transmitted through the rolling elements", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "At 30 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 30 mm seats can bend past the compensation range long before the load rating is exhausted.", "Oscillating pivots fail differently: rocking through a small angle concentrates wear in the same roller positions — inspect those zones, and consider rotating the assembly's clock position at service intervals.", "Contamination, not fatigue, kills most small needle bearings: with raceways this narrow, one hard particle dents a full-width line — seal the housing even when the bearing execution itself is open.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKXR 30 Z facing the working thrust.", "Minimum axial load is a real requirement: below factor A 0.00049 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "The 22.9/38 kN ratings and 140 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "What are the dimensions and ratings of the NKXR 30 Z?", "a": "A NKXR 30 Z measures 30 mm bore/Fw × 42 mm outside diameter × 30 mm width (1.181 × 1.654 × 1.181 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 22.9 kN, static C0 38 kN, fatigue limit Pu 4.8 kN, limiting speed 6,000 r/min, reference speed 3,000 r/min, mass about 140 g. Axial ratings of the thrust part: dynamic Ca 27 kN (Ca), static C0a 78 kN (C0a), minimum load factor A 0.00049; the thrust set carries load in one direction only." }, { "q": "How is the NKXR 30 Z designation read?", "a": "NKXR = needle roller radial part + full complement needle thrust part for a 30 mm shaft: 42 mm OD, 30 mm overall height, the highest axial rating of the combined needle families." }, { "q": "Can the NKXR 30 Z run on an unhardened shaft?", "a": "The radial needle part of the NKXR 30 Z runs directly on the 30 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "How should the NKXR 30 Z be mounted?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 30 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." } ], "cross_ref": [ { "equiv_sku": "NKXR30", "equiv_brand": "SKF", "level": "full", "note": "Same 30×42×30 mm envelope and equivalent catalogue ratings; NKXR30 is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "RNA6905", "equiv_brand": "SKF", "level": "partial", "note": "Same 30×42×30 mm envelope, but catalogue C/C0 differ between the executions (22.9/38 vs 38/62 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NX30-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (30×42×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NX30", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (30×42×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX30-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (30×42×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX30", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (30×42×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKXR30-Z", "NKXR 30 Z" ], "locale_variants": {} }, { "sku": "NKXR35", "brand": "SKF", "manufacturer_designation": "NKXR 35", "series": "NKXR-series", "type": "needle", "d_mm": 35, "D_mm": 47, "B_mm": 30, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 24.6, "static_load_kN": 45, "fatigue_load_limit_kN": 5.6, "max_rpm": 5600, "reference_speed_rpm": 2800, "limiting_speed_rpm": 5600, "weight_g": 160, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "NKXR 35 is the heavy-thrust member of the combined needle roller family: 35 mm radial seat, 47 mm OD, and a full complement of thrust needles rated 29 kN (Ca) dynamic / 93 kN (C0a) static. The code NKXR 35 identifies the construction exactly — needle radial part, needle thrust part — for a 35 mm shaft; the thrust set is one-directional and must face the working axial load. One-direction thrust only — reverse axial loads lift the packed needle set off its raceway; arrange a second unit mirrored or a separate thrust bearing for reversing duty. Selection arithmetic for the combined unit: radial C 24.6 kN, radial C0 45 kN, axial dynamic 29 kN (Ca) and axial static 93 kN (C0a); combine them with the equivalent-load factors from the catalogue before checking L10. These units run at low speed with high axial load: verify lubricant channeling at the washer faces after the first hour, as the packed thrust set pumps grease axially out of the 30 mm tall envelope.", "applications": [ "turntables and slewing pivots with shock loads", "press-fit die set guide positions", "heavy screw presses and clamping spindles", "crane slew rings and kingposts at low speed" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "cage pocket wear and roller skew after sustained operation with too little radial preload", "abrasive paste formation from dust ingressing past open ends without effective housing seals", "electrical erosion on VFD-driven shafts without brush or insulated mounting", "thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry" ], "pitfalls": [ "At 35 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 35 mm seats can bend past the compensation range long before the load rating is exhausted.", "Hardness is load capacity: in families without an inner ring the 35 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.", "The quoted 24.6/45 kN ratings are SKF catalogue values for this exact execution (NKXR 35); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.", "Minimum axial load is a real requirement: below factor A 0.00069 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "Height stack-up is easy to mis-check: the thrust-washer part adds height beyond a plain needle bearing, and clamping the stack solid over it preloads the thrust set beyond its rating.", "The 24.6/45 kN ratings and 160 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "What are the dimensions and ratings of the NKXR 35?", "a": "A NKXR 35 measures 35 mm bore/Fw × 47 mm outside diameter × 30 mm width (1.378 × 1.85 × 1.181 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 24.6 kN, static C0 45 kN, fatigue limit Pu 5.6 kN, limiting speed 5,600 r/min, reference speed 2,800 r/min, mass about 160 g. Axial ratings of the thrust part: dynamic Ca 29 kN (Ca), static C0a 93 kN (C0a), minimum load factor A 0.00069; the thrust set carries load in one direction only." }, { "q": "How is the NKXR 35 designation read?", "a": "NKXR = needle roller radial part + full complement needle thrust part for a 35 mm shaft: 47 mm OD, 30 mm overall height, the highest axial rating of the combined needle families." }, { "q": "Can the NKXR 35 run on an unhardened shaft?", "a": "The radial needle part of the NKXR 35 runs directly on the 35 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "How should the NKXR 35 be mounted?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 35 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." } ], "cross_ref": [ { "equiv_sku": "NKXR35-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 35×47×30 mm envelope and equivalent catalogue ratings; NKXR35-Z is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "RNA6906", "equiv_brand": "SKF", "level": "partial", "note": "Same 35×47×30 mm envelope, but catalogue C/C0 differ between the executions (24.6/45 vs 42.9/75 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NX35-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (35×47×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NX35", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (35×47×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX35-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (35×47×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX35", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (35×47×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKXR35", "NKXR 35" ], "locale_variants": {} }, { "sku": "NKXR35-Z", "brand": "SKF", "manufacturer_designation": "NKXR 35 Z", "series": "NKXR-series", "type": "needle", "d_mm": 35, "D_mm": 47, "B_mm": 30, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 24.6, "static_load_kN": 45, "fatigue_load_limit_kN": 5.6, "max_rpm": 5600, "reference_speed_rpm": 2800, "limiting_speed_rpm": 5600, "weight_g": 170, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "The combined needle roller / full complement needle thrust bearings execution NKXR 35 Z measures 35×47×30 mm: radial dynamic 24.6 kN, axial dynamic 29 kN (Ca) — the thrust needle complement gives roughly twice the axial rating of a same-size thrust ball part. The code NKXR 35 Z identifies the construction exactly — needle radial part, needle thrust part — for a 35 mm shaft; the thrust set is one-directional and must face the working axial load. Thrust needle sets tolerate slow speeds and heavy loads: the 5,600 r/min limiting speed is far below ball-thrust equivalents, and lubricant film at the washer faces governs life. Speed ceilings differ by part: 2,800 r/min thermal reference and 5,600 r/min limiting — the thrust element governs, since its washer faces see sliding components of contact. These units run at low speed with high axial load: verify lubricant channeling at the washer faces after the first hour, as the packed thrust set pumps grease axially out of the 30 mm tall envelope.", "applications": [ "turntables and slewing pivots with shock loads", "press-fit die set guide positions", "heavy screw presses and clamping spindles", "crane slew rings and kingposts at low speed" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "cage pocket wear and roller skew after sustained operation with too little radial preload", "abrasive paste formation from dust ingressing past open ends without effective housing seals", "electrical erosion on VFD-driven shafts without brush or insulated mounting", "thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry" ], "pitfalls": [ "At 35 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 35 mm seats can bend past the compensation range long before the load rating is exhausted.", "Oscillating pivots fail differently: rocking through a small angle concentrates wear in the same roller positions — inspect those zones, and consider rotating the assembly's clock position at service intervals.", "Contamination, not fatigue, kills most small needle bearings: with raceways this narrow, one hard particle dents a full-width line — seal the housing even when the bearing execution itself is open.", "Do not treat the axial rating 29 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKXR 35 Z facing the working thrust.", "The 24.6/45 kN ratings and 170 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "How is the NKXR 35 Z designation read?", "a": "NKXR = needle roller radial part + full complement needle thrust part for a 35 mm shaft: 47 mm OD, 30 mm overall height, the highest axial rating of the combined needle families." }, { "q": "Can the NKXR 35 Z run on an unhardened shaft?", "a": "The radial needle part of the NKXR 35 Z runs directly on the 35 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "How should the NKXR 35 Z be mounted?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 35 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "What limits the service life of a NKXR 35 Z?", "a": "Beyond the L10 rating, the practical limits are journal/raceway hardness for the 35 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 6.0 mm radial section leaves no reserve once a raceway is dented or ribboned." } ], "cross_ref": [ { "equiv_sku": "NKXR35", "equiv_brand": "SKF", "level": "full", "note": "Same 35×47×30 mm envelope and equivalent catalogue ratings; NKXR35 is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "RNA6906", "equiv_brand": "SKF", "level": "partial", "note": "Same 35×47×30 mm envelope, but catalogue C/C0 differ between the executions (24.6/45 vs 42.9/75 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NX35-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (35×47×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NX35", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (35×47×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX35-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (35×47×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX35", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (35×47×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKXR35-Z", "NKXR 35 Z" ], "locale_variants": {} }, { "sku": "NKXR40", "brand": "SKF", "manufacturer_designation": "NKXR 40", "series": "NKXR-series", "type": "needle", "d_mm": 40, "D_mm": 52, "B_mm": 32, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 26.4, "static_load_kN": 51, "fatigue_load_limit_kN": 6.3, "max_rpm": 5000, "reference_speed_rpm": 2400, "limiting_speed_rpm": 5000, "weight_g": 200, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "The combined needle roller / full complement needle thrust bearings execution NKXR 40 measures 40×52×32 mm: radial dynamic 26.4 kN, axial dynamic 43 kN (Ca) — the thrust needle complement gives roughly twice the axial rating of a same-size thrust ball part. The code NKXR 40 identifies the construction exactly — needle radial part, needle thrust part — for a 40 mm shaft; the thrust set is one-directional and must face the working axial load. Execution notes: the Z suffix shields the thrust needle set; the full complement part delivers the highest axial rating in the family but needs the minimum axial load (factor A 0.0015) to prevent needle skidding. Selection arithmetic for the combined unit: radial C 26.4 kN, radial C0 51 kN, axial dynamic 43 kN (Ca) and axial static 137 kN (C0a); combine them with the equivalent-load factors from the catalogue before checking L10. Fit with a press against the washer faces only — needles packed without a cage will skew if the assembly is dropped or driven sideways onto the 40 mm seat.", "applications": [ "turntables and slewing pivots with shock loads", "press-fit die set guide positions", "heavy screw presses and clamping spindles", "crane slew rings and kingposts at low speed" ], "failure_modes": [ "raceway spalling once the catalogue L10 life is exceeded or after overload events", "cage pocket wear and roller skew after sustained operation with too little radial preload", "abrasive paste formation from dust ingressing past open ends without effective housing seals", "false brinelling of standby equipment under external vibration", "thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry" ], "pitfalls": [ "At 40 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 40 mm seats can bend past the compensation range long before the load rating is exhausted.", "Hardness is load capacity: in families without an inner ring the 40 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.", "The quoted 26.4/51 kN ratings are SKF catalogue values for this exact execution (NKXR 40); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.", "Minimum axial load is a real requirement: below factor A 0.0015 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "Height stack-up is easy to mis-check: the thrust-washer part adds height beyond a plain needle bearing, and clamping the stack solid over it preloads the thrust set beyond its rating.", "The 26.4/51 kN ratings and 200 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "Can the NKXR 40 run on an unhardened shaft?", "a": "The radial needle part of the NKXR 40 runs directly on the 40 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "How should the NKXR 40 be mounted?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 40 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "What limits the service life of a NKXR 40?", "a": "Beyond the L10 rating, the practical limits are journal/raceway hardness for the 40 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 6.0 mm radial section leaves no reserve once a raceway is dented or ribboned." }, { "q": "What are the dimensions and ratings of the NKXR 40?", "a": "A NKXR 40 measures 40 mm bore/Fw × 52 mm outside diameter × 32 mm width (1.575 × 2.047 × 1.26 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 26.4 kN, static C0 51 kN, fatigue limit Pu 6.3 kN, limiting speed 5,000 r/min, reference speed 2,400 r/min, mass about 200 g. Axial ratings of the thrust part: dynamic Ca 43 kN (Ca), static C0a 137 kN (C0a), minimum load factor A 0.0015; the thrust set carries load in one direction only." } ], "cross_ref": [ { "equiv_sku": "NKXR40-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 40×52×32 mm envelope and equivalent catalogue ratings; NKXR40-Z is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NKX40-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (40×52×32 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX40", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (40×52×32 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKXR40", "NKXR 40" ], "locale_variants": {} }, { "sku": "NKXR40-Z", "brand": "SKF", "manufacturer_designation": "NKXR 40 Z", "series": "NKXR-series", "type": "needle", "d_mm": 40, "D_mm": 52, "B_mm": 32, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 26.4, "static_load_kN": 51, "fatigue_load_limit_kN": 6.3, "max_rpm": 5000, "reference_speed_rpm": 2400, "limiting_speed_rpm": 5000, "weight_g": 210, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "SKF lists NKXR 40 Z where axial capacity dominates: the packed thrust needle set carries 43 kN (Ca) dynamically at the cost of speed, while the caged radial rollers contribute 26.4 kN. In SKF nomenclature NKXR is the highest-capacity combined family: 40 mm shaft seat, packed thrust needles above the radial cage, axial rating 43 kN (Ca) dynamic. Thrust needle sets tolerate slow speeds and heavy loads: the 5,000 r/min limiting speed is far below ball-thrust equivalents, and lubricant film at the washer faces governs life. Selection arithmetic for the combined unit: radial C 26.4 kN, radial C0 51 kN, axial dynamic 43 kN (Ca) and axial static 137 kN (C0a); combine them with the equivalent-load factors from the catalogue before checking L10. These units run at low speed with high axial load: verify lubricant channeling at the washer faces after the first hour, as the packed thrust set pumps grease axially out of the 32 mm tall envelope.", "applications": [ "extruder and mixer thrust positions", "large valve stems under high axial load", "turntables and slewing pivots with shock loads", "press-fit die set guide positions" ], "failure_modes": [ "needle edge loading and raceway denting when the shaft deflects beyond the compensation range", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "abrasive paste formation from dust ingressing past open ends without effective housing seals", "hard-particle indentation in unfiltered lubricant", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "At 40 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 40 mm seats can bend past the compensation range long before the load rating is exhausted.", "Contamination, not fatigue, kills most small needle bearings: with raceways this narrow, one hard particle dents a full-width line — seal the housing even when the bearing execution itself is open.", "Do not interchange envelope-identical needle families blindly: NKXR 40 Z shares its 40×52×32 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKXR 40 Z facing the working thrust.", "Minimum axial load is a real requirement: below factor A 0.0015 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "The 26.4/51 kN ratings and 210 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "Which dimensions does the NKXR 40 Z have?", "a": "A NKXR 40 Z measures 40 mm bore/Fw × 52 mm outside diameter × 32 mm width (1.575 × 2.047 × 1.26 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 26.4 kN, static C0 51 kN, fatigue limit Pu 6.3 kN, limiting speed 5,000 r/min, reference speed 2,400 r/min, mass about 210 g. Axial ratings of the thrust part: dynamic Ca 43 kN (Ca), static C0a 137 kN (C0a), minimum load factor A 0.0015; the thrust set carries load in one direction only." }, { "q": "What does NKXR 40 Z mean in SKF part numbering?", "a": "NKXR = needle roller radial part + full complement needle thrust part for a 40 mm shaft: 52 mm OD, 32 mm overall height, the highest axial rating of the combined needle families." }, { "q": "Does the NKXR 40 Z need a hardened and ground shaft?", "a": "The radial needle part of the NKXR 40 Z runs directly on the 40 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "What mounting mistakes ruin a NKXR 40 Z?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 40 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." } ], "cross_ref": [ { "equiv_sku": "NKXR40", "equiv_brand": "SKF", "level": "full", "note": "Same 40×52×32 mm envelope and equivalent catalogue ratings; NKXR40 is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NKX40-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (40×52×32 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX40", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (40×52×32 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKXR40-Z", "NKXR 40 Z" ], "locale_variants": {} }, { "sku": "NKXR45", "brand": "SKF", "manufacturer_designation": "NKXR 45", "series": "NKXR-series", "type": "needle", "d_mm": 45, "D_mm": 58, "B_mm": 32, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 27.5, "static_load_kN": 57, "fatigue_load_limit_kN": 7.1, "max_rpm": 4500, "reference_speed_rpm": 2200, "limiting_speed_rpm": 4500, "weight_g": 240, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "NKXR 45 is a combined needle roller / full complement needle thrust bearing: caged needle rollers for radial duty plus a packed needle thrust set for the highest axial capacity of any 45 mm combined bearing, per SKF catalogue PUB BU/P1 17000 ch. 7.10. Reading the designation: NKXR marks needle roller + full complement needle thrust, the number the 45 mm shaft seat; 58 mm OD and 32 mm height follow the series plan. Thrust needle sets tolerate slow speeds and heavy loads: the 4,500 r/min limiting speed is far below ball-thrust equivalents, and lubricant film at the washer faces governs life. Speed ceilings differ by part: 2,200 r/min thermal reference and 4,500 r/min limiting — the thrust element governs, since its washer faces see sliding components of contact. Fit with a press against the washer faces only — needles packed without a cage will skew if the assembly is dropped or driven sideways onto the 45 mm seat.", "applications": [ "turntables and slewing pivots with shock loads", "press-fit die set guide positions", "heavy screw presses and clamping spindles", "crane slew rings and kingposts at low speed" ], "failure_modes": [ "needle edge loading and raceway denting when the shaft deflects beyond the compensation range", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "abrasive paste formation from dust ingressing past open ends without effective housing seals", "brinelling of raceways from impact or pressing force transmitted through the rolling elements", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "At 45 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 45 mm seats can bend past the compensation range long before the load rating is exhausted.", "The quoted 27.5/57 kN ratings are SKF catalogue values for this exact execution (NKXR 45); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.", "Oscillating pivots fail differently: rocking through a small angle concentrates wear in the same roller positions — inspect those zones, and consider rotating the assembly's clock position at service intervals.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKXR 45 facing the working thrust.", "Minimum axial load is a real requirement: below factor A 0.0019 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "The 27.5/57 kN ratings and 240 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "Does the NKXR 45 need a hardened and ground shaft?", "a": "The radial needle part of the NKXR 45 runs directly on the 45 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "What mounting mistakes ruin a NKXR 45?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 45 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "Is the NKXR 45 sealed?", "a": "No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty." }, { "q": "Which dimensions does the NKXR 45 have?", "a": "A NKXR 45 measures 45 mm bore/Fw × 58 mm outside diameter × 32 mm width (1.772 × 2.283 × 1.26 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 27.5 kN, static C0 57 kN, fatigue limit Pu 7.1 kN, limiting speed 4,500 r/min, reference speed 2,200 r/min, mass about 240 g. Axial ratings of the thrust part: dynamic Ca 45 kN (Ca), static C0a 153 kN (C0a), minimum load factor A 0.0019; the thrust set carries load in one direction only." } ], "cross_ref": [ { "equiv_sku": "NKXR45-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 45×58×32 mm envelope and equivalent catalogue ratings; NKXR45-Z is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NKX45-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (45×58×32 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX45", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (45×58×32 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKXR45", "NKXR 45" ], "locale_variants": {} }, { "sku": "NKXR45-Z", "brand": "SKF", "manufacturer_designation": "NKXR 45 Z", "series": "NKXR-series", "type": "needle", "d_mm": 45, "D_mm": 58, "B_mm": 32, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 27.5, "static_load_kN": 57, "fatigue_load_limit_kN": 7.1, "max_rpm": 4500, "reference_speed_rpm": 2200, "limiting_speed_rpm": 4500, "weight_g": 260, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "NKXR 45 Z is a combined needle roller / full complement needle thrust bearing: caged needle rollers for radial duty plus a packed needle thrust set for the highest axial capacity of any 45 mm combined bearing, per SKF catalogue PUB BU/P1 17000 ch. 7.10. Reading the designation: NKXR marks needle roller + full complement needle thrust, the number the 45 mm shaft seat; 58 mm OD and 32 mm height follow the series plan. Thrust needle sets tolerate slow speeds and heavy loads: the 4,500 r/min limiting speed is far below ball-thrust equivalents, and lubricant film at the washer faces governs life. The minimum load factor A 0.0019 applies to the thrust part: below that axial load the rolling elements of the thrust set skid, so springs or preload washers are part of the arrangement, not an afterthought. Fit with a press against the washer faces only — needles packed without a cage will skew if the assembly is dropped or driven sideways onto the 45 mm seat.", "applications": [ "large valve stems under high axial load", "turntables and slewing pivots with shock loads", "press-fit die set guide positions", "heavy screw presses and clamping spindles" ], "failure_modes": [ "needle edge loading and raceway denting when the shaft deflects beyond the compensation range", "cage pocket wear and roller skew after sustained operation with too little radial preload", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "false brinelling of standby equipment under external vibration", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "At 45 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 45 mm seats can bend past the compensation range long before the load rating is exhausted.", "Contamination, not fatigue, kills most small needle bearings: with raceways this narrow, one hard particle dents a full-width line — seal the housing even when the bearing execution itself is open.", "Do not interchange envelope-identical needle families blindly: NKXR 45 Z shares its 45×58×32 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.", "Do not treat the axial rating 45 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKXR 45 Z facing the working thrust.", "The 27.5/57 kN ratings and 260 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "What does NKXR 45 Z mean in SKF part numbering?", "a": "NKXR = needle roller radial part + full complement needle thrust part for a 45 mm shaft: 58 mm OD, 32 mm overall height, the highest axial rating of the combined needle families." }, { "q": "Does the NKXR 45 Z need a hardened and ground shaft?", "a": "The radial needle part of the NKXR 45 Z runs directly on the 45 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "What mounting mistakes ruin a NKXR 45 Z?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 45 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." }, { "q": "Is the NKXR 45 Z sealed?", "a": "No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty." } ], "cross_ref": [ { "equiv_sku": "NKXR45", "equiv_brand": "SKF", "level": "full", "note": "Same 45×58×32 mm envelope and equivalent catalogue ratings; NKXR45 is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NKX45-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (45×58×32 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX45", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (45×58×32 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKXR45-Z", "NKXR 45 Z" ], "locale_variants": {} }, { "sku": "NKXR50", "brand": "SKF", "manufacturer_designation": "NKXR 50", "series": "NKXR-series", "type": "needle", "d_mm": 50, "D_mm": 62, "B_mm": 35, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 38, "static_load_kN": 78, "fatigue_load_limit_kN": 9.65, "max_rpm": 4300, "reference_speed_rpm": 2200, "limiting_speed_rpm": 4300, "weight_g": 270, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "SKF lists NKXR 50 where axial capacity dominates: the packed thrust needle set carries 47.5 kN (Ca) dynamically at the cost of speed, while the caged radial rollers contribute 38 kN. Reading the designation: NKXR marks needle roller + full complement needle thrust, the number the 50 mm shaft seat; 62 mm OD and 35 mm height follow the series plan. One-direction thrust only — reverse axial loads lift the packed needle set off its raceway; arrange a second unit mirrored or a separate thrust bearing for reversing duty. Speed ceilings differ by part: 2,200 r/min thermal reference and 4,300 r/min limiting — the thrust element governs, since its washer faces see sliding components of contact. Mounting: the thrust needle complement is held by grease during assembly; fill the washer set, orient toward the axial load, and preload to at least factor A 0.0022 before rotating.", "applications": [ "turntables and slewing pivots with shock loads", "press-fit die set guide positions", "heavy screw presses and clamping spindles", "crane slew rings and kingposts at low speed" ], "failure_modes": [ "needle edge loading and raceway denting when the shaft deflects beyond the compensation range", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "abrasive paste formation from dust ingressing past open ends without effective housing seals", "corrosion pitting from condensation in intermittently operated machinery", "thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor" ], "pitfalls": [ "At 50 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 50 mm seats can bend past the compensation range long before the load rating is exhausted.", "The quoted 38/78 kN ratings are SKF catalogue values for this exact execution (NKXR 50); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.", "Oscillating pivots fail differently: rocking through a small angle concentrates wear in the same roller positions — inspect those zones, and consider rotating the assembly's clock position at service intervals.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKXR 50 facing the working thrust.", "Minimum axial load is a real requirement: below factor A 0.0022 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "The 38/78 kN ratings and 270 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "Is the NKXR 50 sealed?", "a": "No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty." }, { "q": "Which dimensions does the NKXR 50 have?", "a": "A NKXR 50 measures 50 mm bore/Fw × 62 mm outside diameter × 35 mm width (1.969 × 2.441 × 1.378 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 38 kN, static C0 78 kN, fatigue limit Pu 9.65 kN, limiting speed 4,300 r/min, reference speed 2,200 r/min, mass about 270 g. Axial ratings of the thrust part: dynamic Ca 47.5 kN (Ca), static C0a 166 kN (C0a), minimum load factor A 0.0022; the thrust set carries load in one direction only." }, { "q": "What does NKXR 50 mean in SKF part numbering?", "a": "NKXR = needle roller radial part + full complement needle thrust part for a 50 mm shaft: 62 mm OD, 35 mm overall height, the highest axial rating of the combined needle families." }, { "q": "Does the NKXR 50 need a hardened and ground shaft?", "a": "The radial needle part of the NKXR 50 runs directly on the 50 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." } ], "cross_ref": [ { "equiv_sku": "NKXR50-Z", "equiv_brand": "SKF", "level": "full", "note": "Same 50×62×35 mm envelope and equivalent catalogue ratings; NKXR50-Z is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NK50-35-TN", "equiv_brand": "SKF", "level": "partial", "note": "Same 50×62×35 mm envelope, but catalogue C/C0 differ between the executions (38/78 vs 58.3/137 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NKX50-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (50×62×35 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX50", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (50×62×35 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKXR50", "NKXR 50" ], "locale_variants": {} }, { "sku": "NKXR50-Z", "brand": "SKF", "manufacturer_designation": "NKXR 50 Z", "series": "NKXR-series", "type": "needle", "d_mm": 50, "D_mm": 62, "B_mm": 35, "material": "GCr15", "seal_type": "open", "clearance": "CN", "tolerance_class": "P0", "cage_type": "none", "dynamic_load_kN": 38, "static_load_kN": 78, "fatigue_load_limit_kN": 9.65, "max_rpm": 4300, "reference_speed_rpm": 2200, "limiting_speed_rpm": 4300, "weight_g": 290, "weight_estimated": false, "temp_min_c": -40, "temp_max_c": 120, "standard": "DIN 616", "naming_rule_text": "NKXR 50 Z is the heavy-thrust member of the combined needle roller family: 50 mm radial seat, 62 mm OD, and a full complement of thrust needles rated 47.5 kN (Ca) dynamic / 166 kN (C0a) static. In SKF nomenclature NKXR is the highest-capacity combined family: 50 mm shaft seat, packed thrust needles above the radial cage, axial rating 47.5 kN (Ca) dynamic. Thrust needle sets tolerate slow speeds and heavy loads: the 4,300 r/min limiting speed is far below ball-thrust equivalents, and lubricant film at the washer faces governs life. Selection arithmetic for the combined unit: radial C 38 kN, radial C0 78 kN, axial dynamic 47.5 kN (Ca) and axial static 166 kN (C0a); combine them with the equivalent-load factors from the catalogue before checking L10. Fit with a press against the washer faces only — needles packed without a cage will skew if the assembly is dropped or driven sideways onto the 50 mm seat.", "applications": [ "extruder and mixer thrust positions", "large valve stems under high axial load", "turntables and slewing pivots with shock loads", "press-fit die set guide positions" ], "failure_modes": [ "needle edge loading and raceway denting when the shaft deflects beyond the compensation range", "polymer cage deformation when the local temperature exceeds the 120 °C sustained limit", "grease starvation at the roller ends when relubrication intervals are stretched in dirty duty", "brinelling of raceways from impact or pressing force transmitted through the rolling elements", "thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry" ], "pitfalls": [ "At 50 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 50 mm seats can bend past the compensation range long before the load rating is exhausted.", "Reference and limiting speeds are different limits: the 2,200 r/min reference is the thermal criterion under load, The limiting value is mechanical; the reference value is thermal under load, and grease choice moves it substantially.", "Hardness is load capacity: in families without an inner ring the 50 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.", "The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKXR 50 Z facing the working thrust.", "Minimum axial load is a real requirement: below factor A 0.0022 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.", "The 38/78 kN ratings and 290 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only." ], "faq": [ { "q": "Which dimensions does the NKXR 50 Z have?", "a": "A NKXR 50 Z measures 50 mm bore/Fw × 62 mm outside diameter × 35 mm width (1.969 × 2.441 × 1.378 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 38 kN, static C0 78 kN, fatigue limit Pu 9.65 kN, limiting speed 4,300 r/min, reference speed 2,200 r/min, mass about 290 g. Axial ratings of the thrust part: dynamic Ca 47.5 kN (Ca), static C0a 166 kN (C0a), minimum load factor A 0.0022; the thrust set carries load in one direction only." }, { "q": "What does NKXR 50 Z mean in SKF part numbering?", "a": "NKXR = needle roller radial part + full complement needle thrust part for a 50 mm shaft: 62 mm OD, 35 mm overall height, the highest axial rating of the combined needle families." }, { "q": "Does the NKXR 50 Z need a hardened and ground shaft?", "a": "The radial needle part of the NKXR 50 Z runs directly on the 50 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table." }, { "q": "What mounting mistakes ruin a NKXR 50 Z?", "a": "Press on the ring faces only with a fitting sleeve, keep everything square to the 50 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs." } ], "cross_ref": [ { "equiv_sku": "NKXR50", "equiv_brand": "SKF", "level": "full", "note": "Same 50×62×35 mm envelope and equivalent catalogue ratings; NKXR50 is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply." }, { "equiv_sku": "NK50-35-TN", "equiv_brand": "SKF", "level": "partial", "note": "Same 50×62×35 mm envelope, but catalogue C/C0 differ between the executions (38/78 vs 58.3/137 kN) — boundary dimensions match, not a load-rating equivalent." }, { "equiv_sku": "NKX50-Z", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (50×62×35 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." }, { "equiv_sku": "NKX50", "equiv_brand": "SKF", "level": "full", "note": "Envelope-identical (50×62×35 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction." } ], "source_ref": "https://www.skf.com/group/products/rolling-bearings/needle-roller-bearings", "catalog_ver": "SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust", "extracted_at": "2026-09-26", "last_verified": "2026-09-26", "confidence_score": 0.7, "status": "published", "aliases": [ "NKXR50-Z", "NKXR 50 Z" ], "locale_variants": {} } ]