51184 bearing: complete specifications & equivalents
The 51184 is a ISO 104 radial bearing sized 420 x 500 x 65 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 420 mm |
| Outer diameter D | 500 mm |
| Width B | 65 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Basic dynamic load rating C | 395 kN |
| Basic static load rating C0 | 2110 kN |
| Fatigue load limit Pu | 44.5 kN |
| Limiting speed (mechanical) | 470 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 24400 g |
| Manufacturer designation | NTN 51184 |
| 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 | 16.535 in |
|---|---|
| Outer diameter D | 19.685 in |
| Width B | 2.559 in |
| ISO bore code | 84 |
| Radial section height (D−d)/2 | 40 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) | 41 of 46 |
| Bore above smallest 51100-series size | 410 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 51184 model number is decoded
The light-section 51100 thrust family entry 51184 stacks a shaft washer, ball-and-cage set and housing washer into 65 mm of height over a 420 mm bore. The designation is 511 is the dimension series (light-section 51100 thrust family) plus 84 encodes the 420 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. Size selection ends with the minimum-load check: at the 470 r/min class speed, the balls need a defined axial preload to keep rolling instead of skidding. Keep the support faces square: a housing face out of perpendicular by a few hundredths over the 500 mm OD already tilts the raceway and concentrates the 2110 kN static capacity on a few balls.
Typical equipment & failure modes
Common applications
- bulk-handler stacker/reclaimer thrust pivots
- heavy rotary furnace and kiln thrust points
- vertical hydro and pump-turbine thrust supports
- large marine winch and windlass 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
- 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
- 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
- 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
- For a 420 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 420 mm bore it gives up load to gain OD, height and limiting-speed headroom.
- Below the minimum axial load the balls skid; the catalogue Ca of 395 kN never saves a bearing that is running too lightly loaded at 470 r/min.
- Never substitute a double-direction bearing drawing part-for-part: the single-direction 51184 stack height of 65 mm and washer set differ from the double-direction execution.
- Single-direction means exactly that: thrust on 51184 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 395/C0a 2110 kN ratings and 44.5 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 51184; 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 51184?
51184 is a single-direction thrust ball bearing to ISO 104: 420 mm shaft-washer bore, 500 mm outside diameter, 65 mm stack height (16.535 x 19.685 x 2.559 in). From NTN Ball and Roller Bearings CAT.No.2203E: axial Ca 395 kN, C0a 2110 kN and a 44.5 kN fatigue load limit Pu; the grease limiting speed is 470 r/min and the oil rating 670 r/min; mass about 24400 g.
How is the 51184 designation structured?
511 is the dimension series (light-section 51100 thrust family); 84 encodes the 420 mm bore (bore code x 5). The 500 mm OD and 65 mm height follow the ISO 104 boundary plan for that series.
Can 51184 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 51184?
At the 470 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 51184?
The 420/500/65 mm envelope is ISO 104 interchangeable, but washer bore codes, raceway osculation and ratings are maker-specific. Re-verify Ca 395 kN / C0a 2110 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.