51110 bearing: complete specifications & equivalents
The 51110 is a ISO 104 radial bearing sized 50 x 70 x 14 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 50 mm |
| Outer diameter D | 70 mm |
| Width B | 14 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Basic dynamic load rating C | 28.8 kN |
| Basic static load rating C0 | 75.5 kN |
| Fatigue load limit Pu | 3.4 kN |
| Limiting speed (mechanical) | 3100 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 161 g |
| Manufacturer designation | NTN 51110 |
| 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 | 1.969 in |
|---|---|
| Outer diameter D | 2.756 in |
| Width B | 0.551 in |
| ISO bore code | 10 |
| Radial section height (D−d)/2 | 10 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) | 11 of 46 |
| Bore above smallest 51100-series size | 40 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 51110-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 51110 model number is decoded
From the light-section 51100 thrust family, 51110 measures 50 mm through the shaft washer, 70 mm over the outside and 14 mm in assembled height. Two fields make up the code — 511 is the dimension series (light-section 51100 thrust family) and 10 encodes the 50 mm bore (bore code x 5). Because the contact points run at 90 deg to the shaft, none of the rating is available for radial load — not even incidentally. If the duty is high speed with light thrust, check the minimum axial load formula first; a too-large thrust ball bearing fails by skid long before its Ca of 28.8 kN is ever approached. Preload or working clearance must guarantee the minimum axial load at the catalogue speed; a spring or dead-weight arrangement is the usual answer on high-speed vertical shafts.
Typical equipment & failure modes
Common applications
- press and punch-machine thrust seats
- conveyor vertical-drive thrust positions
- vertical motor and pump thrust shoes
- machine-tool tailstock and steady-rest screws
Known failure patterns
- cage pocket wear and ball skid polish after long running below the minimum axial load, the balls sliding instead of rolling on the washers
- housing-washer rocking on an out-of-square support face, seen as uneven wear around the raceway circle and rising running torque
- early fatigue from thrust reversal hammering the unloaded raceway, because the bearing has no contact surfaces for the opposite direction
- washer face corrosion under long standstill in humid service, later printed into the raceway as evenly spaced pitting
- cage breakage after repeated shock reversal banged the ball set against the pocket bridges
Selection pitfalls — read before you substitute
- In this size class the frequent miss is washer identification: keep the catalogued shaft/housing washer pairing of the 50 mm size together from unpacking to assembly.
- The 511 light section is the speed-friendly end of the thrust-ball plan — for the same 50 mm bore it gives up load to gain OD, height and limiting-speed headroom.
- 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.
- Radial load is the silent killer here: a belt pull or gear force on the same shaft must land on a radial bearing, because 51110 has no radial capacity at all.
- Single-direction means exactly that: thrust on 51110 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 28.8/C0a 75.5 kN ratings and 3.4 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 51110; 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 51110?
51110 is a single-direction thrust ball bearing to ISO 104: 50 mm shaft-washer bore, 70 mm outside diameter, 14 mm stack height (1.969 x 2.756 x 0.551 in). From NTN Ball and Roller Bearings CAT.No.2203E: axial Ca 28.8 kN, C0a 75.5 kN and a 3.4 kN fatigue load limit Pu; the grease limiting speed is 3,100 r/min and the oil rating 4,500 r/min; mass about 161 g.
How is the 51110 designation structured?
511 is the dimension series (light-section 51100 thrust family); 10 encodes the 50 mm bore (bore code x 5). The 70 mm OD and 14 mm height follow the ISO 104 boundary plan for that series.
Can 51110 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 51110?
At the 3,100 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 51110?
The 50/70/14 mm envelope is ISO 104 interchangeable, but washer bore codes, raceway osculation and ratings are maker-specific. Re-verify Ca 28.8 kN / C0a 75.5 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.