51100 bearing: complete specifications & equivalents
The 51100 is a ISO 104 radial bearing sized 10 x 24 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 | 10 mm |
| Outer diameter D | 24 mm |
| Width B | 9 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Basic dynamic load rating C | 10 kN |
| Basic static load rating C0 | 14 kN |
| Fatigue load limit Pu | 0.63 kN |
| Limiting speed (mechanical) | 6700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 21 g |
| Manufacturer designation | NTN 51100 |
| 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 | 0.394 in |
|---|---|
| Outer diameter D | 0.945 in |
| Width B | 0.354 in |
| ISO bore code | 00 |
| Radial section height (D−d)/2 | 7 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) | 1 of 46 |
| Bore above smallest 51100-series size | 0 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 51100-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 51100 model number is decoded
The light-section 51100 thrust family entry 51100 stacks a shaft washer, ball-and-cage set and housing washer into 9 mm of height over a 10 mm bore. The designation is 511 is the dimension series (light-section 51100 thrust family) plus the bore code 00 maps to the 10 mm bore by the standard table. Catalogue mass is about 21 g for the full washer-and-cage stack. The 10/24/9 envelope follows ISO 104, so dimensional interchange holds between makers — raceway osculation and ratings do not automatically follow. Keep the support faces square: a housing face out of perpendicular by a few hundredths over the 24 mm OD already tilts the raceway and concentrates the 14 kN static capacity on a few balls.
Typical equipment & failure modes
Common applications
- valve actuator and gearbox thrust seats
- food-machine vertical auger shafts
- laboratory centrifuge and mixer thrust ends
- small vertical pump and agitator thrust positions
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
- edge loading from a shaft washer mounted off-centre, cutting the contact ellipse short at one side of the track
- 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
- Small thrust washers of 10 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 10 mm bore it gives up load to gain OD, height and limiting-speed headroom.
- A housing washer pressed tight in its seat cannot self-centre; the resulting eccentric running shows up as cage wear long before raceway fatigue.
- Below the minimum axial load the balls skid; the catalogue Ca of 10 kN never saves a bearing that is running too lightly loaded at 6,700 r/min.
- The 6,700 r/min speed figure assumes the catalogue lubrication state; at high speed the limiting factor is often the minimum load, not the rating table.
- The Ca 10/C0a 14 kN ratings and 0.63 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 51100; 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 51100?
51100 is a single-direction thrust ball bearing to ISO 104: 10 mm shaft-washer bore, 24 mm outside diameter, 9 mm stack height (0.394 x 0.945 x 0.354 in). From NTN Ball and Roller Bearings CAT.No.2203E: axial Ca 10 kN, C0a 14 kN and a 0.63 kN fatigue load limit Pu; the grease limiting speed is 6,700 r/min and the oil rating 9,500 r/min; mass about 21 g.
How is the 51100 designation structured?
511 is the dimension series (light-section 51100 thrust family); the bore code 00 maps to the 10 mm bore by the standard table. The 24 mm OD and 9 mm height follow the ISO 104 boundary plan for that series.
Can 51100 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 51100?
At the 6,700 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 51100?
The 10/24/9 mm envelope is ISO 104 interchangeable, but washer bore codes, raceway osculation and ratings are maker-specific. Re-verify Ca 10 kN / C0a 14 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.