NSK7218CTYDUMP4Super-Precision Angular Contact Bearing – 90 mm ID, 160 mm OD, 30 mm Width, Open, 15° Contact Angle, Matched Duplex Pair

Product Description

What this part is

NSK 7218CTYDUMP4 super-precision angular contact ball bearing. Bore: 90 mm. Outside diameter: 160 mm. Width: 30 mm per bearing. Series: 7200. Contact angle: 15°. Precision Class: P4 (ABEC 7). Single row per bearing, open on both faces, ball-guided machined cage. Country of origin as recorded on this listing: United Kingdom.

Decoding the designation

7218 = 72 series, 90 mm bore. C = 15° contact angle. TY = ball-guided cage. DUM = universally matchable duplex pair, medium preload. P4 = ABEC 7 precision. Searchable forms: 7218CTYDUMP4, 7218-CTY-DUM-P4, 7218 CTY DUM P4, 7218C, 7218CTYDUMPA7. GTIN: 029176090493.

What these specs mean in practice

A 15° contact angle gives high speed capability and high radial stiffness. A ball-guided cage is centred by the ball complement rather than by a ring land, which keeps the cage self-aligning under changing load direction. NSK rates ball-guided cages at a lower limiting speed than outer-ring-guided cages, and the figures below are the ball-guided values. Medium preload raises spindle rigidity to 187 N/µm against 126 N/µm at light preload.

Load ratings and speed

Basic dynamic load rating Cr: 155 kN (34,850 lbf) per bearing. Basic static load rating C0r: 105 kN (23,600 lbf) per bearing. Permissible axial load Pa: 72.0 kN. Limiting speed: 9,000 rpm on grease and 11,000 rpm on oil or oil-air. Effective load centre a: 31.7 mm. Mass: 2.20 kg (4.85 lb) per bearing.

Quantity and configuration

Two pieces ship, matching the DUM duplex designation. Rings are universally ground, so the pair mounts back-to-back, face-to-face or in tandem. Medium preload as supplied: 1,865 N with an axial rigidity of 187 N/µm in a DB or DF pair.

Fitting notes

Shaft abutment diameter da: 100 mm minimum. Housing abutment diameters Da 150 mm and Db 154 mm maximum. Shaft and housing fillet radii ra 2 mm and rb 1 mm maximum. Chamfer dimensions r 2 mm and r1 1 mm minimum. Recommended grease charge: 12 g per bearing. As a preloaded matched pair the bearings carry no running clearance, so the internal clearance field reads N/A.

Interchange guidance

Direct equivalents at the same 15° angle, P4 class and medium preload: SKF 7218 CD/P4ADGB, Fafnir 2MM218WI-DUM, RHP 7218CTRDUMP4, FAG B7218C.T.P4S.UL. Related size: 7218A5 shares the 90 x 160 x 30 mm envelope at a 25° contact angle, and 7218CTYDULP4 is the same bearing at light preload. Both are different parts rather than substitutions.