51411 bearing: complete specifications & equivalents
The 51411 is a ISO 104 radial bearing sized 55 x 120 x 48 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 55 mm |
| Outer diameter D | 120 mm |
| Width B | 48 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Basic dynamic load rating C | 178 kN |
| Basic static load rating C0 | 360 kN |
| Fatigue load limit Pu | 16.2 kN |
| Limiting speed (mechanical) | 1300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 2520 g |
| Manufacturer designation | NTN 51411 |
| 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 | 2.165 in |
|---|---|
| Outer diameter D | 4.724 in |
| Width B | 1.89 in |
| ISO bore code | 11 |
| Radial section height (D−d)/2 | 32.5 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) | 7 of 20 |
| Bore above smallest 51400-series size | 30 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 51411-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 51411 model number is decoded
From the extra-heavy 51400 thrust family, 51411 measures 55 mm through the shaft washer, 120 mm over the outside and 48 mm in assembled height. Decoding 51411: 514 is the dimension series (extra-heavy 51400 thrust family), with 11 encodes the 55 mm bore (bore code x 5). The washer section here is 32.5 mm of radial height, and the catalogue couples it with Ca 178 kN / C0a 360 kN. Where misalignment between shaft and housing seats is expected, the spherical-seat washer executions (listed separately in the catalogue) absorb what the flat-seat 51411 cannot. 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
- machine-tool tailstock and steady-rest screws
- medium crane hook blocks and slewing jibs
- extruder and mixer thrust housings
- winch and capstan vertical shafts
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
- 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
- edge loading from a shaft washer mounted off-centre, cutting the contact ellipse short at one side of the track
- washer face corrosion under long standstill in humid service, later printed into the raceway as evenly spaced pitting
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 55 mm size together from unpacking to assembly.
- 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 360 kN leaves dents that later become fatigue origins — crane-hook and press applications need the static check, not just the life calculation.
- A housing washer pressed tight in its seat cannot self-centre; the resulting eccentric running shows up as cage wear long before raceway fatigue.
- The C0a of 360 kN is a static rating: sizing continuous working thrust from C0a alone overstates what the raceway survives.
- The Ca 178/C0a 360 kN ratings and 16.2 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 51411; 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 51411?
51411 is a single-direction thrust ball bearing to ISO 104: 55 mm shaft-washer bore, 120 mm outside diameter, 48 mm stack height (2.165 x 4.724 x 1.89 in). From NTN Ball and Roller Bearings CAT.No.2203E: axial Ca 178 kN, C0a 360 kN and a 16.2 kN fatigue load limit Pu; the grease limiting speed is 1,300 r/min and the oil rating 1,800 r/min; mass about 2520 g.
How is the 51411 designation structured?
514 is the dimension series (extra-heavy 51400 thrust family); 11 encodes the 55 mm bore (bore code x 5). The 120 mm OD and 48 mm height follow the ISO 104 boundary plan for that series.
Can 51411 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 51411?
At the 1,300 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 51411?
The 55/120/48 mm envelope is ISO 104 interchangeable, but washer bore codes, raceway osculation and ratings are maker-specific. Re-verify Ca 178 kN / C0a 360 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.