51144 bearing: complete specifications & equivalents
The 51144 is a ISO 104 radial bearing sized 220 x 270 x 37 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 220 mm |
| Outer diameter D | 270 mm |
| Width B | 37 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Basic dynamic load rating C | 177 kN |
| Basic static load rating C0 | 740 kN |
| Fatigue load limit Pu | 21.3 kN |
| Limiting speed (mechanical) | 920 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 4270 g |
| Manufacturer designation | NTN 51144 |
| 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 | 8.661 in |
|---|---|
| Outer diameter D | 10.63 in |
| Width B | 1.457 in |
| ISO bore code | 44 |
| Radial section height (D−d)/2 | 25 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) | 31 of 46 |
| Bore above smallest 51100-series size | 210 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 51144 model number is decoded
51144 is the 220 mm member of NTN's light-section 51100 thrust family: 270 mm across the washers, 37 mm tall. Two fields make up the code — 511 is the dimension series (light-section 51100 thrust family) and 44 encodes the 220 mm bore (bore code x 5). With Ca 177 kN and C0a 740 kN, each mm of shaft bore carries about 0.80 kN of dynamic axial rating. For a 220 mm shaft with combined radial-plus-axial load, pair this bearing with a separate radial bearing — the thrust ball bearing must never be asked to carry the radial share. Keep the support faces square: a housing face out of perpendicular by a few hundredths over the 270 mm OD already tilts the raceway and concentrates the 740 kN static capacity on a few balls.
Typical equipment & failure modes
Common applications
- heavy press and mill screwdown thrust seats
- crane slew-ring auxiliary thrust positions
- large mixer and reactor vertical shafts
- bulk-handler stacker/reclaimer thrust pivots
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
- cage breakage after repeated shock reversal banged the ball set against the pocket bridges
Selection pitfalls — read before you substitute
- For a 220 mm bore thrust bearing, the seating surfaces and oil supply decide service life; at this size a field-improvised housing is the usual root cause behind "premature" failures.
- The 511 light section is the speed-friendly end of the thrust-ball plan — for the same 220 mm bore it gives up load to gain OD, height and limiting-speed headroom.
- Swapping the shaft and housing washers is an easy assembly error on the 220 mm size — the bores differ only slightly, but the wrong pairing walks off-centre under load.
- Below the minimum axial load the balls skid; the catalogue Ca of 177 kN never saves a bearing that is running too lightly loaded at 920 r/min.
- 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.
- The Ca 177/C0a 740 kN ratings and 21.3 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 51144; 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 51144?
51144 is a single-direction thrust ball bearing to ISO 104: 220 mm shaft-washer bore, 270 mm outside diameter, 37 mm stack height (8.661 x 10.63 x 1.457 in). From NTN Ball and Roller Bearings CAT.No.2203E: axial Ca 177 kN, C0a 740 kN and a 21.3 kN fatigue load limit Pu; the grease limiting speed is 920 r/min and the oil rating 1,300 r/min; mass about 4270 g.
How is the 51144 designation structured?
511 is the dimension series (light-section 51100 thrust family); 44 encodes the 220 mm bore (bore code x 5). The 270 mm OD and 37 mm height follow the ISO 104 boundary plan for that series.
Can 51144 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 51144?
At the 920 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 51144?
The 220/270/37 mm envelope is ISO 104 interchangeable, but washer bore codes, raceway osculation and ratings are maker-specific. Re-verify Ca 177 kN / C0a 740 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.