51213 bearing: complete specifications & equivalents
The 51213 is a ISO 104 radial bearing sized 65 x 100 x 27 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 65 mm |
| Outer diameter D | 100 mm |
| Width B | 27 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Basic dynamic load rating C | 75 kN |
| Basic static load rating C0 | 189 kN |
| Fatigue load limit Pu | 8.5 kN |
| Limiting speed (mechanical) | 1900 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 767 g |
| Manufacturer designation | NTN 51213 |
| 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 & 51200-series range
| Bore d | 2.559 in |
|---|---|
| Outer diameter D | 3.937 in |
| Width B | 1.063 in |
| ISO bore code | 13 |
| Radial section height (D−d)/2 | 17.5 mm |
| Smallest bore in 51200-series | 10 mm |
| Largest outer diameter in 51200-series | 520 mm |
| Width range across 51200-series | 11–112 mm |
| Bore position in 51200-series (smallest first) | 14 of 39 |
| Bore above smallest 51200-series size | 55 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 51213-SKF | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 65×100×27 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 51213 model number is decoded
At 65 x 100 x 27 mm, NTN 51213 sits in the medium-section 51200 thrust family of the single-direction thrust programme. NTN builds the number from 512 is the dimension series (medium-section 51200 thrust family); 13 encodes the 65 mm bore (bore code x 5). With Ca 75 kN and C0a 189 kN, each mm of shaft bore carries about 1.15 kN of dynamic axial rating. Where misalignment between shaft and housing seats is expected, the spherical-seat washer executions (listed separately in the catalogue) absorb what the flat-seat 51213 cannot. Preload or working clearance must guarantee the minimum axial load at the catalogue speed; a spring or dead-weight arrangement is the usual answer on high-speed vertical shafts.
Typical equipment & failure modes
Common applications
- rolling-mill screwdown and adjustment screws
- heavy press and forging-machine thrust seats
- ship winch and capstan thrust shafts
- crusher main-shaft 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
- contamination pitting from particles settling on the horizontal housing washer — the classic failure of vertical-shaft grease-lubricated seats
- lubricant starvation scoring on the raceway track when grease is thrown outward by centrifugal effect and never replaced
Selection pitfalls — read before you substitute
- At 65 mm bore the washers are heavy enough to sag out of square during assembly — support the stack horizontally where possible and verify face runout before loading.
- The 512 medium section is the default choice: balanced height and capacity for general vertical-shaft duty at 65 mm bore.
- Shock thrust above C0a 189 kN leaves dents that later become fatigue origins — crane-hook and press applications need the static check, not just the life calculation.
- Do not reuse a thrust bearing to "absorb" shaft thermal growth — the bearing clamps axially, so growth must be handled on the radial-bearing side of the arrangement.
- 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 75/C0a 189 kN ratings and 8.5 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 51213; 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 51213?
51213 is a single-direction thrust ball bearing to ISO 104: 65 mm shaft-washer bore, 100 mm outside diameter, 27 mm stack height (2.559 x 3.937 x 1.063 in). From NTN Ball and Roller Bearings CAT.No.2203E: axial Ca 75 kN, C0a 189 kN and a 8.5 kN fatigue load limit Pu; the grease limiting speed is 1,900 r/min and the oil rating 2,700 r/min; mass about 767 g.
How is the 51213 designation structured?
512 is the dimension series (medium-section 51200 thrust family); 13 encodes the 65 mm bore (bore code x 5). The 100 mm OD and 27 mm height follow the ISO 104 boundary plan for that series.
Can 51213 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 51213?
At the 1,900 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 51213?
The 65/100/27 mm envelope is ISO 104 interchangeable, but washer bore codes, raceway osculation and ratings are maker-specific. Re-verify Ca 75 kN / C0a 189 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.