Timken52375-90109Double Row Tapered Roller Bearing Assembly, TDO Configuration, 3.750 in Bore x 6.375 in Outside Diameter x 3.2499 in Wide, 0.012 in End Play — Complete Set With Double Cup and Spacer

Product Description

What this part is

A complete Timken TDO double-row tapered roller bearing assembly, assembly number 52375-90109. TDO stands for Tapered Double Outer: two single-row cone assemblies running back-to-back in one double cup, with a ground spacer setting the pair.

The assembly comprises

Two 52375 cone assemblies (inner races with rollers and cages)
One 52637D double cup (one outer race carrying two raceways)
One X2S-52375 spacer ring

Correcting the source data

The original listing gave the type as “Tapered Roller Bearing Cone” and offered a 3-3/4 in bore with a 6-3/8 in outside diameter but no width. It is not a cone — it is a complete two-row assembly — and we have added the missing assembled width and end-play figures from Timken’s published data. The type correction matters: a buyer looking for a complete TDO unit would never have found this listing as written.

Published ratings and mounting data

Timken publishes the following for assembly 52375-90109

Bore (d): 3.750 in (95.25 mm)
Outside diameter (D): 6.375 in (161.93 mm)
Assembled width: 3.2499 in (82.55 mm)
Assembled end play: 0.012 in
Configuration: TDO, back-to-back

Dynamic and static load ratings for this specific assembly number were not retrievable from a manufacturer source we will stand behind, so those cells are deliberately blank. We have not substituted the ratings of the single-row 52375/52637 — that is a one-row bearing with a different cup, and its figures would understate this unit.

What these specs mean in practice

The 0.012 in factory end play is the number that matters most on a TDO. It is set by the ground width of the spacer against these particular cones and cup, and it is why the assembly must be kept together as a set. Mix components between assemblies and you lose the setting; clamp the unit only partially and the end play is meaningless.

Functionally, this unit does in one envelope what two opposed single-row bearings do across a shaft: carries radial load, takes thrust in both directions, and locates the shaft axially. The back-to-back row arrangement gives it real resistance to overturning moments, so it suits short stiff shafts, pinion positions and any place where a cantilevered load has to be held square.

Quantity and configuration

Seven complete assemblies in stock — an unusually deep holding for an inch TDO of this size, so multiples and rebuild-kit quantities are available. Note that the “(2) 52375” in our stock record means two cones within each assembly, not two bearings.

Fitting notes

Supplied pre-set; keep each assembly’s parts together. Normally the double cup is the clamped member in the housing with the cones free on the shaft, or the reverse — follow the equipment manufacturer’s arrangement. Press only on the ring being fitted, never through rollers or cages. Because the end play is factory-ground, do not attempt to adjust it by shimming.

Interchange guidance

52375 and 52637D are industry-standard inch tapered designations. The 52637D double cup is shared across several cone numbers — 52387/52637D and 52400/52637D give 3.875 in and 4.000 in bores in the same 6.375 in outside diameter — so identify by the cone number or the assembly number, never by the cup alone. A related non-adjustable variant, NA52375/52637D (TNA), also exists.