51328 bearing: complete specifications & equivalents
The 51328 is a ISO 104 radial bearing sized 140 x 240 x 80 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 140 mm |
| Outer diameter D | 240 mm |
| Width B | 80 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Basic dynamic load rating C | 350 kN |
| Basic static load rating C0 | 1050 kN |
| Fatigue load limit Pu | 34.5 kN |
| Limiting speed (mechanical) | 670 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 15300 g |
| Manufacturer designation | NTN 51328 |
| 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 & 51300-series range
| Bore d | 5.512 in |
|---|---|
| Outer diameter D | 9.449 in |
| Width B | 3.15 in |
| ISO bore code | 28 |
| Radial section height (D−d)/2 | 50 mm |
| Smallest bore in 51300-series | 25 mm |
| Largest outer diameter in 51300-series | 340 mm |
| Width range across 51300-series | 18–110 mm |
| Bore position in 51300-series (smallest first) | 19 of 25 |
| Bore above smallest 51300-series size | 115 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 51328-M | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 140×240×80 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 51328 model number is decoded
51328 is an NTN single-direction thrust ball bearing of the heavy-section 51300 thrust family: 140 mm bore, 240 mm outside diameter, 80 mm overall height in NTN Ball and Roller Bearings CAT.No.2203E. The designation is 513 is the dimension series (heavy-section 51300 thrust family) plus 28 encodes the 140 mm bore (bore code x 5). Catalogue mass is about 15300 g for the full washer-and-cage stack. Choose the heavy-section 51300 thrust family when the shaft carries pure thrust in one direction at moderate speed — vertical shafts are the textbook case. On a vertical shaft, pack grease between the washers and plan a relubrication path — centrifugal effect drives grease outward and the track runs dry without it.
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
- 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
- For a 140 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 513 heavy section buys capacity with a larger 240 mm OD and taller stack — check the housing space before upgrading a 512 position to this series.
- 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.
- Single-direction means exactly that: thrust on 51328 in the wrong direction separates the washers and drops the ball set — if reversal is possible even during coast-down, engineer against it.
- The 670 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 350/C0a 1050 kN ratings and 34.5 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 51328; 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 51328?
51328 is a single-direction thrust ball bearing to ISO 104: 140 mm shaft-washer bore, 240 mm outside diameter, 80 mm stack height (5.512 x 9.449 x 3.15 in). From NTN Ball and Roller Bearings CAT.No.2203E: axial Ca 350 kN, C0a 1050 kN and a 34.5 kN fatigue load limit Pu; the grease limiting speed is 670 r/min and the oil rating 960 r/min; mass about 15300 g.
How is the 51328 designation structured?
513 is the dimension series (heavy-section 51300 thrust family); 28 encodes the 140 mm bore (bore code x 5). The 240 mm OD and 80 mm height follow the ISO 104 boundary plan for that series.
Can 51328 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 51328?
At the 670 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 51328?
The 140/240/80 mm envelope is ISO 104 interchangeable, but washer bore codes, raceway osculation and ratings are maker-specific. Re-verify Ca 350 kN / C0a 1050 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.