51330 bearing: complete specifications & equivalents
The 51330 is a ISO 104 radial bearing sized 150 x 250 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 | 150 mm |
| Outer diameter D | 250 mm |
| Width B | 80 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Basic dynamic load rating C | 360 kN |
| Basic static load rating C0 | 1130 kN |
| Fatigue load limit Pu | 36 kN |
| Limiting speed (mechanical) | 660 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 16100 g |
| Manufacturer designation | NTN 51330 |
| 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 | 5.906 in |
|---|---|
| Outer diameter D | 9.843 in |
| Width B | 3.15 in |
| ISO bore code | 30 |
| 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) | 20 of 25 |
| Bore above smallest 51300-series size | 125 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 51330-M | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 150×250×80 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 51330 model number is decoded
NTN 51330 belongs to the heavy-section 51300 thrust family of single-direction thrust ball bearings: 150 / 250 / 80 mm (shaft bore / OD / height). NTN builds the number from 513 is the dimension series (heavy-section 51300 thrust family); 30 encodes the 150 mm bore (bore code x 5). Flat-seat washers make the bearing tolerant of simple housings but demand square faces: the whole 360 kN rating assumes the load arrives truly axial. If the duty is high speed with light thrust, check the minimum axial load formula first; a too-large thrust ball bearing fails by skid long before its Ca of 360 kN is ever approached. 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 mixer and reactor vertical shafts
- bulk-handler stacker/reclaimer thrust pivots
- heavy rotary furnace and kiln thrust points
- vertical hydro and pump-turbine thrust supports
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
- housing-washer rocking on an out-of-square support face, seen as uneven wear around the raceway circle and rising running torque
- rapid flaking after radial load was allowed onto the bearing — a single-direction thrust ball bearing carries axial load only
- lubricant starvation scoring on the raceway track when grease is thrown outward by centrifugal effect and never replaced
- lubricant starvation scoring on the raceway track when grease is thrown outward by centrifugal effect and never replaced
Selection pitfalls — read before you substitute
- For a 150 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 250 mm OD and taller stack — check the housing space before upgrading a 512 position to this series.
- A housing washer pressed tight in its seat cannot self-centre; the resulting eccentric running shows up as cage wear long before raceway fatigue.
- Below the minimum axial load the balls skid; the catalogue Ca of 360 kN never saves a bearing that is running too lightly loaded at 660 r/min.
- Never substitute a double-direction bearing drawing part-for-part: the single-direction 51330 stack height of 80 mm and washer set differ from the double-direction execution.
- The Ca 360/C0a 1130 kN ratings and 36 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 51330; 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 51330?
51330 is a single-direction thrust ball bearing to ISO 104: 150 mm shaft-washer bore, 250 mm outside diameter, 80 mm stack height (5.906 x 9.843 x 3.15 in). From NTN Ball and Roller Bearings CAT.No.2203E: axial Ca 360 kN, C0a 1130 kN and a 36 kN fatigue load limit Pu; the grease limiting speed is 660 r/min and the oil rating 940 r/min; mass about 16100 g.
How is the 51330 designation structured?
513 is the dimension series (heavy-section 51300 thrust family); 30 encodes the 150 mm bore (bore code x 5). The 250 mm OD and 80 mm height follow the ISO 104 boundary plan for that series.
Can 51330 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 51330?
At the 660 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 51330?
The 150/250/80 mm envelope is ISO 104 interchangeable, but washer bore codes, raceway osculation and ratings are maker-specific. Re-verify Ca 360 kN / C0a 1130 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.