NX7-ZTN bearing: complete specifications & equivalents
The NX7-ZTN is a DIN 616 radial bearing sized 7 x 14 x 18 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 7 mm |
| Outer diameter D | 14 mm |
| Width B | 18 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 2.81 kN |
| Basic static load rating C0 | 2.75 kN |
| Fatigue load limit Pu | 0.29 kN |
| Reference speed (thermal) | 10000 rpm |
| Limiting speed (mechanical) | 6000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 14 g |
| Manufacturer designation | NX 7 ZTN |
| Standard | DIN 616 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.8 needle roller / thrust ball, full complement thrust part |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.8 needle roller / thrust ball, full complement thrust part) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.8 needle roller / thrust ball, full complement thrust part); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.com.
Dimensions in inches & NX-series range
| Bore d | 0.276 in |
|---|---|
| Outer diameter D | 0.551 in |
| Width B | 0.709 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 3.5 mm |
| Smallest bore in NX-series | 7 mm |
| Largest outer diameter in NX-series | 47 mm |
| Width range across NX-series | 18–30 mm |
| Bore position in NX-series (smallest first) | 1 of 9 |
| Bore above smallest NX-series size | 0 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NX7-TN | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 7×14×18 mm envelope and equivalent catalogue ratings; NX7-TN is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the NX7-ZTN model number is decoded
NX 7 ZTN packs radial and thrust capacity into 7×14×18 mm: needle rollers caged around the shaft, thrust balls packed without a cage above them, axial dynamic rating 3.45 kN (Ca). Reading the designation: NX marks needle roller + full complement thrust ball, the number the 7 mm shaft seat; 14 mm OD and 18 mm overall height follow the series plan. Full complement thrust parts run slower than caged ones: observe the 6,000 r/min limiting speed, and expect the thrust part to govern the thermal ceiling. Selection arithmetic for the combined unit: radial C 2.81 kN, radial C0 2.75 kN, axial dynamic 3.45 kN (Ca) and axial static 5 kN (C0a); combine them with the equivalent-load factors from the catalogue before checking L10. The full complement thrust set has no cage to retain the balls — hold them with grease during assembly and never rotate the shaft before the axial preload (at least factor A 0.00013) is applied.
Typical equipment & failure modes
Common applications
- small hoisting and winch drums
- actuator output shafts
- screw jack and lifting screw spindles
- valve and dosing pump stems with slow axial push
Known failure patterns
- 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
Selection pitfalls — read before you substitute
- At Fw 7 mm the rolling elements are under two millimetres long — handle the NX 7 ZTN like a watch part: one dropped assembly, one over-pressed cup or one coarse journal finish outweighs any catalogue rating difference.
- The quoted 2.81/2.75 kN ratings are SKF catalogue values for this exact execution (NX 7 ZTN); 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.
- 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 3.45 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 2.81/2.75 kN ratings and 14 g mass are SKF catalogue values transcribed from ch. 7.8 of PUB BU/P1 17000 (PDF table page 656); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
What does NX 7 ZTN mean in SKF part numbering?
NX = needle roller radial part + full complement thrust ball part for a 7 mm shaft; the catalogue plan completes 14 mm OD and 18 mm overall height. The packed thrust set maximises axial capacity at low speed.
Does the NX 7 ZTN need a hardened and ground shaft?
The radial needle part of the NX 7 ZTN runs directly on the 7 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.
What mounting mistakes ruin a NX 7 ZTN?
Press on the ring faces only with a fitting sleeve, keep everything square to the 7 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.
Is the NX 7 ZTN sealed?
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.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.8 needle roller / thrust ball, full complement thrust part on 2026-09-26. Read our editorial & correction policy.