51126-NTN bearing: complete specifications & equivalents
The 51126-NTN is a ISO 104 radial bearing sized 130 x 170 x 30 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 130 mm |
| Outer diameter D | 170 mm |
| Width B | 30 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Basic dynamic load rating C | 104 kN |
| Basic static load rating C0 | 350 kN |
| Fatigue load limit Pu | 13 kN |
| Limiting speed (mechanical) | 1300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1730 g |
| Manufacturer designation | NTN 51126 |
| Standard | ISO 104 |
| Catalog version | NTN Ball and Roller Bearings CAT.No.2203E |
| Last verified | 2026-10-01 |
Source: catalog reference (NTN Ball and Roller Bearings CAT.No.2203E) · extracted 2026-10-01
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN Ball and Roller Bearings CAT.No.2203E); NTN® is a trademark of NTN Corporation, used here for identification only — mpnbase is not an authorized NTN distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at ntnglobal.com.
Dimensions in inches & 51100-series range
| Bore d | 5.118 in |
|---|---|
| Outer diameter D | 6.693 in |
| Width B | 1.181 in |
| ISO bore code | 26 |
| Radial section height (D−d)/2 | 20 mm |
| Smallest bore in 51100-series | 10 mm |
| Largest outer diameter in 51100-series | 640 mm |
| Width range across 51100-series | 9–85 mm |
| Bore position in 51100-series (smallest first) | 23 of 46 |
| Bore above smallest 51100-series size | 120 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 51126-NTN model number is decoded
51126 is an NTN single-direction thrust ball bearing of the light-section 51100 thrust family: 130 mm bore, 170 mm outside diameter, 30 mm overall height in NTN Ball and Roller Bearings CAT.No.2203E. The designation is 511 is the dimension series (light-section 51100 thrust family) plus 26 encodes the 130 mm bore (bore code x 5). On speed, the grease limiting speed is 1,300 r/min and the oil rating 1,900 r/min. Choose the light-section 51100 thrust family when the shaft carries pure thrust in one direction at moderate speed — vertical shafts are the textbook case. On a vertical shaft, pack grease between the washers and plan a relubrication path — centrifugal effect drives grease outward and the track runs dry without it.
Typical equipment & failure modes
Common applications
- heavy rotary furnace and kiln thrust points
- vertical hydro and pump-turbine thrust supports
- large marine winch and windlass shafts
- heavy press and mill screwdown thrust seats
Known failure patterns
- ball and raceway smearing from gyroscopic spin when the bearing runs fast under too little axial load — the minimum-load rule exists exactly for this
- fretting between shaft washer and shaft when the seat is cut loose — the washer creeps, the centre line shifts and the balls start running off-track
- rapid flaking after radial load was allowed onto the bearing — a single-direction thrust ball bearing carries axial load only
- washer face corrosion under long standstill in humid service, later printed into the raceway as evenly spaced pitting
- contamination pitting from particles settling on the horizontal housing washer — the classic failure of vertical-shaft grease-lubricated seats
Selection pitfalls — read before you substitute
- For a 130 mm bore thrust bearing, the seating surfaces and oil supply decide service life; at this size a field-improvised housing is the usual root cause behind "premature" failures.
- The 511 light section is the speed-friendly end of the thrust-ball plan — for the same 130 mm bore it gives up load to gain OD, height and limiting-speed headroom.
- The C0a of 350 kN is a static rating: sizing continuous working thrust from C0a alone overstates what the raceway survives.
- The C0a of 350 kN is a static rating: sizing continuous working thrust from C0a alone overstates what the raceway survives.
- A housing washer pressed tight in its seat cannot self-centre; the resulting eccentric running shows up as cage wear long before raceway fatigue.
- The Ca 104/C0a 350 kN ratings and 13 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 51126; raceway geometry legitimately differs between manufacturers, so re-verify ratings and washer identification before substituting another make.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 51126?
51126 is a single-direction thrust ball bearing to ISO 104: 130 mm shaft-washer bore, 170 mm outside diameter, 30 mm stack height (5.118 x 6.693 x 1.181 in). From NTN Ball and Roller Bearings CAT.No.2203E: axial Ca 104 kN, C0a 350 kN and a 13 kN fatigue load limit Pu; the grease limiting speed is 1,300 r/min and the oil rating 1,900 r/min; mass about 1730 g.
How is the 51126 designation structured?
511 is the dimension series (light-section 51100 thrust family); 26 encodes the 130 mm bore (bore code x 5). The 170 mm OD and 30 mm height follow the ISO 104 boundary plan for that series.
Can 51126 carry radial load or reversing thrust?
No. The raceways contact the balls at 90 deg to the shaft, so the rating is purely axial and single-direction. Radial load must be carried by a separate radial bearing, and reversing thrust needs a second thrust bearing or a double-direction execution.
Why does NTN specify a minimum axial load for 51126?
At the 1,300 r/min class speed, centrifugal and gyroscopic effects make an under-loaded ball set skid and smear instead of roll. The catalogue minimum-load formula gives the axial preload — from the machine weight, springs or a dead-weight — that keeps the contact rolling.
What should be checked before substituting another make for 51126?
The 130/170/30 mm envelope is ISO 104 interchangeable, but washer bore codes, raceway osculation and ratings are maker-specific. Re-verify Ca 104 kN / C0a 350 kN, the speed figures and the shaft/housing washer identification against the donor catalogue.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN Ball and Roller Bearings CAT.No.2203E on 2026-10-01. Read our editorial & correction policy.