51405 bearing: complete specifications & equivalents
The 51405 is a ISO 104 radial bearing sized 25 x 60 x 24 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 25 mm |
| Outer diameter D | 60 mm |
| Width B | 24 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Basic dynamic load rating C | 55.5 kN |
| Basic static load rating C0 | 89.5 kN |
| Fatigue load limit Pu | 4.05 kN |
| Limiting speed (mechanical) | 2600 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 330 g |
| Manufacturer designation | NTN 51405 |
| 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 & 51400-series range
| Bore d | 0.984 in |
|---|---|
| Outer diameter D | 2.362 in |
| Width B | 0.945 in |
| ISO bore code | 05 |
| Radial section height (D−d)/2 | 17.5 mm |
| Smallest bore in 51400-series | 25 mm |
| Largest outer diameter in 51400-series | 300 mm |
| Width range across 51400-series | 24–120 mm |
| Bore position in 51400-series (smallest first) | 1 of 20 |
| Bore above smallest 51400-series size | 0 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 51405-SKF | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 25×60×24 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
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 51405 model number is decoded
51405 is an NTN single-direction thrust ball bearing of the extra-heavy 51400 thrust family: 25 mm bore, 60 mm outside diameter, 24 mm overall height in NTN Ball and Roller Bearings CAT.No.2203E. The designation is 514 is the dimension series (extra-heavy 51400 thrust family) plus 05 encodes the 25 mm bore (bore code x 5). Catalogue mass is about 330 g for the full washer-and-cage stack. Where misalignment between shaft and housing seats is expected, the spherical-seat washer executions (listed separately in the catalogue) absorb what the flat-seat 51405 cannot. 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
- 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
- cage pocket wear and ball skid polish after long running below the minimum axial load, the balls sliding instead of rolling on the washers
- 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 25 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 514 extra-heavy section is the top of the thrust-ball plan at this bore; beyond it the catalogue moves to spherical roller thrust bearings.
- Shock thrust above C0a 89.5 kN leaves dents that later become fatigue origins — crane-hook and press applications need the static check, not just the life calculation.
- Radial load is the silent killer here: a belt pull or gear force on the same shaft must land on a radial bearing, because 51405 has no radial capacity at all.
- The 2,600 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 55.5/C0a 89.5 kN ratings and 4.05 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 51405; 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 51405?
51405 is a single-direction thrust ball bearing to ISO 104: 25 mm shaft-washer bore, 60 mm outside diameter, 24 mm stack height (0.984 x 2.362 x 0.945 in). From NTN Ball and Roller Bearings CAT.No.2203E: axial Ca 55.5 kN, C0a 89.5 kN and a 4.05 kN fatigue load limit Pu; the grease limiting speed is 2,600 r/min and the oil rating 3,700 r/min; mass about 330 g.
How is the 51405 designation structured?
514 is the dimension series (extra-heavy 51400 thrust family); 05 encodes the 25 mm bore (bore code x 5). The 60 mm OD and 24 mm height follow the ISO 104 boundary plan for that series.
Can 51405 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 51405?
At the 2,600 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 51405?
The 25/60/24 mm envelope is ISO 104 interchangeable, but washer bore codes, raceway osculation and ratings are maker-specific. Re-verify Ca 55.5 kN / C0a 89.5 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.