51102 bearing: complete specifications & equivalents
The 51102 is a ISO 104 radial bearing sized 15 x 28 x 9 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 15 mm |
| Outer diameter D | 28 mm |
| Width B | 9 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Basic dynamic load rating C | 10.5 kN |
| Basic static load rating C0 | 16.8 kN |
| Fatigue load limit Pu | 0.76 kN |
| Limiting speed (mechanical) | 6200 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 24 g |
| Manufacturer designation | NTN 51102 |
| 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 | 0.591 in |
|---|---|
| Outer diameter D | 1.102 in |
| Width B | 0.354 in |
| ISO bore code | 02 |
| Radial section height (D−d)/2 | 6.5 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) | 3 of 46 |
| Bore above smallest 51100-series size | 5 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 51102-SKF | SKF | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
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 51102 model number is decoded
51102 is the 15 mm member of NTN's light-section 51100 thrust family: 28 mm across the washers, 9 mm tall. Two fields make up the code — 511 is the dimension series (light-section 51100 thrust family) and the bore code 02 maps to the 15 mm bore by the standard table. Because the contact points run at 90 deg to the shaft, none of the rating is available for radial load — not even incidentally. For a 15 mm shaft with combined radial-plus-axial load, pair this bearing with a separate radial bearing — the thrust ball bearing must never be asked to carry the radial share. Mount the stack in order and confirm the shaft washer sits against its shoulder before loading: pressing through the balls brinells the raceway on the spot.
Typical equipment & failure modes
Common applications
- bench drill-press and tapping-machine spindles
- automotive steering-gear and clutch release points
- small crane hook and swivel-joint thrust supports
- valve actuator and gearbox 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
- cage breakage after repeated shock reversal banged the ball set against the pocket bridges
- cage breakage after repeated shock reversal banged the ball set against the pocket bridges
Selection pitfalls — read before you substitute
- Small thrust washers of 15 mm bore bend if the shaft shoulder is rough — check burrs before seating, and never press on the housing washer to drive the shaft washer home.
- The 511 light section is the speed-friendly end of the thrust-ball plan — for the same 15 mm bore it gives up load to gain OD, height and limiting-speed headroom.
- Single-direction means exactly that: thrust on 51102 in the wrong direction separates the washers and drops the ball set — if reversal is possible even during coast-down, engineer against it.
- Grease in a horizontal-washer seat stays only if the housing is designed to hold it; open vertical arrangements need an oil bath or a grease-retaining cover.
- Single-direction means exactly that: thrust on 51102 in the wrong direction separates the washers and drops the ball set — if reversal is possible even during coast-down, engineer against it.
- The Ca 10.5/C0a 16.8 kN ratings and 0.76 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 51102; 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 51102?
51102 is a single-direction thrust ball bearing to ISO 104: 15 mm shaft-washer bore, 28 mm outside diameter, 9 mm stack height (0.591 x 1.102 x 0.354 in). From NTN Ball and Roller Bearings CAT.No.2203E: axial Ca 10.5 kN, C0a 16.8 kN and a 0.76 kN fatigue load limit Pu; the grease limiting speed is 6,200 r/min and the oil rating 8,800 r/min; mass about 24 g.
How is the 51102 designation structured?
511 is the dimension series (light-section 51100 thrust family); the bore code 02 maps to the 15 mm bore by the standard table. The 28 mm OD and 9 mm height follow the ISO 104 boundary plan for that series.
Can 51102 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 51102?
At the 6,200 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 51102?
The 15/28/9 mm envelope is ISO 104 interchangeable, but washer bore codes, raceway osculation and ratings are maker-specific. Re-verify Ca 10.5 kN / C0a 16.8 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.