51203 bearing
17 × 35 mm · dynamic rating 16.3 kN · static rating 27 kN. Dimensions, load ratings, designation meaning, life estimates and equivalent parts.
51203 specification
| Designation | 51203 |
| Type | Single-direction thrust ball bearing |
| Series | 512 light-medium |
| Bore diameter d | 17 mm |
| Outside diameter D | 35 mm |
| Basic dynamic load rating C | 16.3 kN (16,300 N) |
| Basic static load rating C0 | 27 kN (27,000 N) |
| Ratio C0/C | 1.66 |
| Speed guide, grease lubrication | 9,500 rpm |
| Life exponent p | 3 (ball bearing) |
Values come from the Rotec AI bearing catalogue and are indicative. Confirm against the manufacturer's current catalogue before ordering. Not every dimension (such as width) is listed here.
What the designation 51203 means
| Code | Meaning |
|---|---|
| 512 | Single-direction thrust ball bearing, light-medium series (flat seat washers) |
| 03 | bore code "03" = 17 mm (one of the four fixed small-bore codes, not the ×5 rule) |
Basic rating life of the 51203
Basic rating life is L10 = (C / P)p million revolutions, where P is the equivalent dynamic load and p = 3 (ball bearing). For a 51203 with C = 16.3 kN, the table shows what that gives at different load levels. It is the ISO 281 basic life only: it does not include lubrication, contamination, misalignment or reliability modifiers.
| C / P | P as share of C | L10 (million rev) | L10 at 1,500 rpm | L10 at 3,000 rpm |
|---|---|---|---|---|
| 3 | 33.3% | 27 | 300 | 150 |
| 5 | 20.0% | 125 | 1,400 | 690 |
| 8 | 12.5% | 512 | 5,700 | 2,800 |
| 12 | 8.3% | 1,728 | 19,200 | 9,600 |
For example, a C / P of 5 means the equivalent load is 3.26 kN on this bearing. Use the Load Calculator to work out P for your actual radial and axial loads.
Equivalents of the 51203
Brand-by-brand equivalents for this exact designation are not yet in the Rotec AI cross-reference tables. The Cross-Reference tool accepts SKF, FAG, NSK, NTN, Timken, Koyo and NRB designations, and shows what is catalogued.
Where the 51203 is used
Thrust ball / thrust roller bearings are chosen for: Predominantly axial load. Typical equipment: Vertical pumps, extruders, turbines, marine and heavy gear drives. Thrust roller for higher axial capacity and shock.
Other sizes in the same series
The 51203 is size 2 of 28 in the Rotec AI catalogue for the “512 light-medium” series. The next size down, the 51202, has a bore of 15 mm and a dynamic rating of 15.9 kN. The next size up, the 51204, has a bore of 20 mm and a rating of 21.2 kN (+30%).
Common problems on bearings like the 51203
Most field failures trace back to lubrication, contamination, fits and alignment rather than the bearing itself. These guides explain how to recognise and prevent them:
Questions about the 51203
What are the dimensions of a 51203 bearing?
The 51203 has a bore of 17 mm and an outside diameter of 35 mm. It is a single-direction thrust ball bearing. Series: 512 light-medium.
What is the load rating of a 51203 bearing?
In the Rotec AI catalogue the 51203 has a basic dynamic load rating C of 16.3 kN and a basic static load rating C0 of 27 kN. Always confirm against the manufacturer's current catalogue.
What is the equivalent of a 51203 bearing?
Brand equivalents for the 51203 are not yet in the Rotec AI tables. Use the Cross-Reference tool to check other designations.