NSK 51109 dimensions and axial-load reference
Read the complete assembly size
NSK 51109 is a single-direction thrust ball bearing reference with flat seat. Its nominal assembly envelope is 45×65×14 mm: shaft bore d = 45 mm, overall diameter D = 65 mm and total height T = 14 mm. A loose washer or cage measurement is not the height of the complete assembly.
Axial direction and support arrangement
This separable construction uses a shaft washer, a ball-and-cage assembly and a housing washer. It supports axial force in one direction. 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 = 28.1 kN and the basic static axial rating is C0a = 69 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.
Speed and lubrication
The catalogue lists 3400 r/min for grease lubrication and 5000 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 d bore and distinguish it from the housing washer with bore D1 = 47 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.
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.
Technical basis:NSK Rolling Bearings for Industrial Machinery, E1103d (2025), Part C, C298–C299; 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.
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