51207 bearing: complete specifications & equivalents
The 51207 is a ISO 104 radial bearing sized 35 x 62 x 18 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 35 mm |
| Outer diameter D | 62 mm |
| Width B | 18 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Basic dynamic load rating C | 39 kN |
| Basic static load rating C0 | 78 kN |
| Fatigue load limit Pu | 3.55 kN |
| Limiting speed (mechanical) | 2900 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 215 g |
| Manufacturer designation | NTN 51207 |
| 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 | 1.378 in |
|---|---|
| Outer diameter D | 2.441 in |
| Width B | 0.709 in |
| ISO bore code | 07 |
| Radial section height (D−d)/2 | 13.5 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) | 8 of 39 |
| Bore above smallest 51200-series size | 25 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 51207-SKF | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 35×62×18 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 51207 model number is decoded
51207 is the 35 mm member of NTN's medium-section 51200 thrust family: 62 mm across the washers, 18 mm tall. Reading the code: 512 is the dimension series (medium-section 51200 thrust family), and 07 encodes the 35 mm bore (bore code x 5). On speed, the grease limiting speed is 2,900 r/min and the oil rating 4,200 r/min. Where misalignment between shaft and housing seats is expected, the spherical-seat washer executions (listed separately in the catalogue) absorb what the flat-seat 51207 cannot. The shaft washer (bore 35 mm, tight on the shaft) and the housing washer (slightly looser bore) are not interchangeable — check the catalogue bore codes before pressing anything on.
Typical equipment & failure modes
Common applications
- medium crane hook blocks and slewing jibs
- extruder and mixer thrust housings
- winch and capstan vertical shafts
- press and punch-machine thrust seats
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
- contamination pitting from particles settling on the horizontal housing washer — the classic failure of vertical-shaft grease-lubricated seats
- edge loading from a shaft washer mounted off-centre, cutting the contact ellipse short at one side of the track
Selection pitfalls — read before you substitute
- In this size class the frequent miss is washer identification: keep the catalogued shaft/housing washer pairing of the 35 mm size together from unpacking to assembly.
- The 512 medium section is the default choice: balanced height and capacity for general vertical-shaft duty at 35 mm bore.
- Shock thrust above C0a 78 kN leaves dents that later become fatigue origins — crane-hook and press applications need the static check, not just the life calculation.
- Single-direction means exactly that: thrust on 51207 in the wrong direction separates the washers and drops the ball set — if reversal is possible even during coast-down, engineer against it.
- A housing washer pressed tight in its seat cannot self-centre; the resulting eccentric running shows up as cage wear long before raceway fatigue.
- The Ca 39/C0a 78 kN ratings and 3.55 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 51207; 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 51207?
51207 is a single-direction thrust ball bearing to ISO 104: 35 mm shaft-washer bore, 62 mm outside diameter, 18 mm stack height (1.378 x 2.441 x 0.709 in). From NTN Ball and Roller Bearings CAT.No.2203E: axial Ca 39 kN, C0a 78 kN and a 3.55 kN fatigue load limit Pu; the grease limiting speed is 2,900 r/min and the oil rating 4,200 r/min; mass about 215 g.
How is the 51207 designation structured?
512 is the dimension series (medium-section 51200 thrust family); 07 encodes the 35 mm bore (bore code x 5). The 62 mm OD and 18 mm height follow the ISO 104 boundary plan for that series.
Can 51207 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 51207?
At the 2,900 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 51207?
The 35/62/18 mm envelope is ISO 104 interchangeable, but washer bore codes, raceway osculation and ratings are maker-specific. Re-verify Ca 39 kN / C0a 78 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.