Bower56425/56650DDouble-Row TDO Tapered Roller Bearing Assembly, 4.250 in Bore x 6.500 in OD, Two Cones in One Double Cup

Product Description

What this part is

This is a two-row tapered roller bearing in the TDO configuration, Tapered Double Outer. Two 56425 cone assemblies (inner rings with rollers and cages) run in a single wide 56650D double cup. Bore is 4.250 in, cup outside diameter is 6.500 in, from the 56000 inch series.

Decoding the designation

56425 is the cone number in the 56000 inch series and sets the 4.250 in bore. 56650D is the cup number with a trailing D for double cup: one wide outer ring carrying two opposed raceways in place of two separate cups, which is what makes this a two-row bearing rather than a single-row cone-and-cup set. TDO is the resulting arrangement, with the two rows sitting back-to-back inside the double cup.

Why a TDO rather than two single-row bearings

A TDO takes thrust in both directions, so it locates a shaft axially on its own without a second bearing opposing it. Because the two rows are separated by the width of the double cup, it also reacts an overturning couple between them, giving moment stiffness from a single housing bore and a single shoulder. That combination is why TDO units are the standard choice for wheel ends, crane wheels and sheaves, conveyor pulleys and gearbox output shafts carrying a belt or chain pull, where the load is not purely radial and the shaft is short or overhung.

Published dimensions

Bore (d): 4.250 in / 107.95 mm. Cup outside diameter (D): 6.500 in / 165.10 mm. Single-row assembly width (T), 56425/56650: 1.4375 in / 36.51 mm.

A note on the brand

Bower is a long-established American tapered roller bearing name, later associated with BCA and the Federal-Mogul group. 56425 and 56650D are industry-standard inch designations rather than Bower-proprietary numbers. The dimensions are fixed by the standard, so a Bower 56425/56650D is dimensionally interchangeable with a Timken, NSK or other maker’s part of the same number. Timken and NSK both catalogue the 56425/56650 pairing, and NSK publishes it as a series.

Mounting data

The internal endplay of a TDO is ground in at the factory as a controlled cone backface stack height, and the resulting clearance is whatever the assembly was built for.

Quantity and configuration

Each unit is one bearing: two cones plus one double cup.

Interchange guidance

Cross-references: 56425/56650D, 56425-56650D, 56425 56650D, 56650D, 56650-D. Related components and assemblies in the same series: 56425 (cone), 56650 (single cup), 56650CD, 56425W/56650, NA56425SW/56650CD, NA56425SW/56650D. Also catalogued by Timken and by NSK as the 56425/56650 series.