NSK 54318 dimensions and axial-load reference
Read the complete assembly size
NSK 54318 is a double-direction thrust ball bearing reference with aligning seat. Its nominal assembly envelope is 75×155×97.2 mm: shaft bore d2 = 75 mm, overall diameter D = 155 mm and total height T5 = 97.2 mm. A loose washer or cage measurement is not the height of the complete assembly.
Axial direction and support arrangement
A central shaft washer sits between two ball-and-cage assemblies and two housing washers. It supports axial force in either direction. Double direction describes axial force, not clockwise versus anticlockwise rotation. This is a thrust-only construction. It cannot be chosen as the sole radial support for a shaft. Radial force and overturning loads need a separately verified support arrangement.
Axial ratings, not permissible working loads
The printed basic dynamic axial rating is Ca = 214 kN and the basic static axial rating is C0a = 525 kN. These values belong to the catalogue assembly and standard cage. They are not radial Cr/C0r values and do not by themselves establish an allowable operating load or a guaranteed life. The two axial directions do not justify doubling either rating.
Speed and lubrication
The catalogue lists 1100 r/min for grease lubrication and 1600 r/min for oil lubrication. These are lubrication-specific limiting speeds, not permission to run every installation continuously at that speed. The actual load, lubricant delivery, temperature and heat removal still need checking. A minimum axial load is required to avoid ball/washer slippage; this source table does not provide a model-specific minimum-load force.
Installation checks before selecting this model
Identify the shaft washer by the d2 bore and distinguish it from the housing washer with bore D1 = 93 mm. Keep the raceway faces towards the balls. Confirm the seating surfaces, shoulders, fillets, retention and separate radial support against the machine drawing. The mounting dimensions in the parameter table are geometric references, not a complete machine assembly procedure.
Why the usual bore-number shortcut is unsafe
The table shows d2 = 75 mm as the central shaft-washer bore; the separate d = 90 mm dimension belongs to the adjacent shaft geometry. Do not use d, D1 or the last two digits of the designation as a substitute for the actual bore column.
Aligning seat versus the U assembly
This catalogue designation has an aligning seat but is not the U-listed assembly with a separate aligning seat washer. Its height T5 = 97.2 mm must not be replaced with the flat-seat or U-assembly height. Confirm the matching seating arrangement; no universal allowable misalignment angle is supplied by this table.
Selection and mounting limits
- No machine fitment or direct replacement approval follows from equal boundary dimensions. Compare the construction, load directions, ratings, speed, fits and full marking.
- No grease fill, temperature limit, installed preload, retaining-nut torque, numerical clearance or CAD file is established by these table rows. Missing information has not been borrowed from another model.
- The standard-cage ratings can change if the cage or number of balls changes. A different suffix requires its own specification.
Different seat constructions in this source row
These links describe different assemblies, not approved substitutes:NSK 52318·NSK 54318U.
Technical basis:NSK Rolling Bearings for Industrial Machinery, E1103d (2025), Part C, C308–C309; construction and identification C296–C297. Source checked 2026-10-01. BearingScope independently organises factual catalogue data for lookup and comparison; it does not sell bearings or approve machine modifications.
Thrust ball bearing size and construction guide·Search by dimensions·Compare recorded models
Product specifications
Metric and imperial values are paired where the manufacturer provides both. Expand a section to review its parameters.
Core specifications5 parameters
| Parameter | Symbol | Value |
|---|---|---|
| Variant / construction | Axial deep groove ball bearing | |
| Bore diameter | d | 75 mm |
| Outside diameter | D | 155 mm |
| Width | B | 97.2 mm |
| Mass | ≈m | 7.33 kg |
Mounting dimensions3 parameters
| Parameter | Symbol | Value |
|---|---|---|
| Maximum housing abutment diameter | Da max. | 120 mm |
| Maximum housing-side fillet radius | ra max. | 1.5 mm |
| Maximum shaft-side fillet radius | rb max. | 1 mm |
Aligning-seat geometry2 parameters
| Parameter | Symbol | Value |
|---|---|---|
| Aligning-seat geometric reference | A1 | 36.5 mm |
| Spherical seat radius | R | 112 mm |
Assembly boundary dimensions3 parameters
| Parameter | Symbol | Value |
|---|---|---|
| Shaft-washer bore diameter | d2 | 75 mm |
| Overall outside diameter | D | 155 mm |
| Complete assembled height | T5 | 97.2 mm |
Axial load ratings2 parameters
| Parameter | Symbol | Value |
|---|---|---|
| Basic dynamic axial load rating | Ca | 214000 N |
| Basic static axial load rating | C0a | 525000 N |
Chamfers2 parameters
| Parameter | Symbol | Value |
|---|---|---|
| Minimum housing-side chamfer | r min. | 1.5 mm |
| Minimum shaft-side chamfer | r1 min. | 1 mm |
Component dimensions5 parameters
| Parameter | Symbol | Value |
|---|---|---|
| Central shaft washer outside diameter | d3 | 155 mm |
| Housing washer bore diameter | D1 | 93 mm |
| Adjacent shaft diameter shown in the catalogue drawing — not the bore | d | 90 mm |
| Central shaft washer thickness | B | 19 mm |
| Partial axial height in the assembly drawing | T6 | 58.1 mm |
Construction3 parameters
| Parameter | Symbol | Value |
|---|---|---|
| Axial load directions | Both directions | |
| Seat construction | Aligning seat | |
| Radial-load support | Not suitable for radial load; separate radial support required |
Lubrication-qualified speed2 parameters
| Parameter | Symbol | Value |
|---|---|---|
| Limiting speed — grease | 1100 r/min | |
| Limiting speed — oil | 1600 r/min |
Mass reference1 parameter
| Parameter | Symbol | Value |
|---|---|---|
| Approximate assembly mass | 7.33 kg |