51418 bearing: complete specifications & equivalents
The 51418 is a ISO 104 radial bearing sized 90 x 190 x 77 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 90 mm |
| Outer diameter D | 190 mm |
| Width B | 77 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Basic dynamic load rating C | 305 kN |
| Basic static load rating C0 | 750 kN |
| Fatigue load limit Pu | 28.6 kN |
| Limiting speed (mechanical) | 790 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 11000 g |
| Manufacturer designation | NTN 51418 |
| 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 | 3.543 in |
|---|---|
| Outer diameter D | 7.48 in |
| Width B | 3.031 in |
| ISO bore code | 18 |
| Radial section height (D−d)/2 | 50 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) | 14 of 20 |
| Bore above smallest 51400-series size | 65 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 51418-M | 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 51418 model number is decoded
From the extra-heavy 51400 thrust family, 51418 measures 90 mm through the shaft washer, 190 mm over the outside and 77 mm in assembled height. The designation is 514 is the dimension series (extra-heavy 51400 thrust family) plus 18 encodes the 90 mm bore (bore code x 5). Flat-seat washers make the bearing tolerant of simple housings but demand square faces: the whole 305 kN rating assumes the load arrives truly axial. Choose the extra-heavy 51400 thrust family when the shaft carries pure thrust in one direction at moderate speed — vertical shafts are the textbook case. After assembly, rotate under light load and check torque and temperature rise — a thrust ball bearing mounted with the washers swapped runs, but fails fast.
Typical equipment & failure modes
Common applications
- large crane hook and swivel assemblies
- rolling-mill screwdown and adjustment screws
- heavy press and forging-machine thrust seats
- ship winch and capstan thrust shafts
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
- cage breakage after repeated shock reversal banged the ball set against the pocket bridges
- 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
- At 90 mm bore the washers are heavy enough to sag out of square during assembly — support the stack horizontally where possible and verify face runout before loading.
- 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.
- Radial load is the silent killer here: a belt pull or gear force on the same shaft must land on a radial bearing, because 51418 has no radial capacity at all.
- Swapping the shaft and housing washers is an easy assembly error on the 90 mm size — the bores differ only slightly, but the wrong pairing walks off-centre under load.
- Never substitute a double-direction bearing drawing part-for-part: the single-direction 51418 stack height of 77 mm and washer set differ from the double-direction execution.
- The Ca 305/C0a 750 kN ratings and 28.6 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 51418; 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 51418?
51418 is a single-direction thrust ball bearing to ISO 104: 90 mm shaft-washer bore, 190 mm outside diameter, 77 mm stack height (3.543 x 7.48 x 3.031 in). From NTN Ball and Roller Bearings CAT.No.2203E: axial Ca 305 kN, C0a 750 kN and a 28.6 kN fatigue load limit Pu; the grease limiting speed is 790 r/min and the oil rating 1,100 r/min; mass about 11000 g.
How is the 51418 designation structured?
514 is the dimension series (extra-heavy 51400 thrust family); 18 encodes the 90 mm bore (bore code x 5). The 190 mm OD and 77 mm height follow the ISO 104 boundary plan for that series.
Can 51418 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 51418?
At the 790 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 51418?
The 90/190/77 mm envelope is ISO 104 interchangeable, but washer bore codes, raceway osculation and ratings are maker-specific. Re-verify Ca 305 kN / C0a 750 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.