Timken938-90091TDO Two-Row Tapered Roller Bearing Assembly – 4.5000 in Bore, 8.3750 in OD, 1.8750 in Cone Width, Class 2, Case-Carburized Steel

Product Description

What this part is

Timken 938-90091 two-row tapered roller bearing assembly. Cone bore 4.5000 in (114.30 mm), cup outside diameter 8.3750 in (212.73 mm), cone width 1.8750 in each. The assembly comprises two 938 cones, one 932CD double cup and one X1S-938 cone spacer. Case carburized steel rings with stamped steel cages and tapered rollers.

Decoding the designation

938 is the cone number and 932 the cup number. The CD suffix on the cup marks a one-piece double cup carrying two raceways, so a single 932CD seats both cones. The X1S prefix identifies a cone spacer, ground to set the axial spacing between the two cones. The -90091 suffix is a Timken assembly number, which specifies a complete factory-matched build and fixes which cup and which spacer accompany the cones.

Quantity and configuration

Four pieces forming one complete bearing: two 938 cones, one 932CD double cup and one X1S-938 cone spacer. The arrangement is TDO, tapered double outer — both cones mounted back to back inside a single common cup.

What these specs mean in practice

A TDO assembly carries radial load together with thrust in both directions, and the spread between the two roller paths gives it genuine moment capacity, which holds shaft alignment under overhung loading. Supplying the assembly as a factory-matched build with its own spacer fixes the internal setting at manufacture, so the bearing goes in at a known clearance rather than being set by hand. Class 2 is Timken’s standard tapered precision grade. Case carburized rings combine a hard raceway with a tough core, which suits shock and heavy intermittent loading better than through-hardened steel.

Mounting dimensions

Effective load centre location is -0.37 in, measured inboard of the reference face. Cone frontface backing diameter is 5.31 in, the minimum diameter a shaft shoulder or backing ring must present to support the cone rib across its full face. Cone backface to-clear radius is 0.14 in, which the shaft fillet must clear.

Fitting notes

The two cones press onto a straight cylindrical shaft seat with the X1S-938 spacer between them and are drawn up solid against it. The double cup fits a single housing bore and is located axially between the housing shoulder and the end cap.

Interchange guidance

A single 938 cone or a single 932 cup covers component replacement inside this assembly. The 938/932D set uses the same cones against a 932D double cup, a different cup variant, making it a related size rather than a direct interchange. Other -900xx numbers on the 938 base are separate factory builds with different spacers and internal settings.