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.

Correcting the source data

The previous listing gave the outside diameter as 6 in. The published dimensions for the 56425 / 56650 pairing are 4.250 in bore x 6.500 in outside diameter — six and a half inches, not six. Anyone machining a housing bore to the old figure would have been half an inch under. The bore figure of 4-1/4 in was correct and is unchanged.

Decoding the designation

56425 — cone number in the 56000 inch series; sets the 4.250 in bore.56650D — cup number with a trailing D for double cup: one wide outer ring carrying two opposed raceways, in place of two separate cups. That single letter is what makes this a two-row bearing rather than a single-row cone-and-cup set.TDO — 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 real 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 — positions where the load is not purely radial and the shaft is short or overhung.

Published dimensions

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

Load ratings, the overall two-row assembly width, the e, K and Y calculation factors, abutment shoulder diameters, fillet radii and weight are not published in the sources located for this reference, and are deliberately omitted rather than estimated or borrowed from a neighbouring series. If you need certified ratings for a life calculation, ask and they can be requested against the standard inch designation.

A note on the brand

Bower is a long-established American tapered roller bearing name, later associated with BCA and the Federal-Mogul group. The important point for a buyer is that 56425 and 56650D are industry-standard inch designations, not Bower-proprietary numbers. The dimensions are fixed by the standard, so a Bower 56425/56650D is dimensionally interchangeable with a Timken, NSK or other reputable maker’s part of the same number. Timken and NSK both catalogue the 56425/56650 pairing, and NSK publishes it as a series.

Fitting notes

Setting a TDO is not the same job as setting two single-row bearings, and this is where they get ruined. The internal endplay of a TDO is ground in at the factory as a controlled cone backface stack height. You clamp the two cones solidly together against the shaft shoulder and the resulting clearance is whatever the assembly was built for — you do not shim it, and you must never mix cones between assemblies, because that destroys the ground endplay.

Press the double cup into the housing square, bearing on the cup face and never on a raceway; a hammer blow on a raceway brinells it and the bearing is noisy from the first hour. Mount the cones by heat or with a tool that pushes on the inner ring face, not on the cage or rollers.

Quantity and configuration

Thirteen complete assemblies are on hand. Each unit is one bearing: two cones plus one double cup. Thirteen units of a large TDO in one place is a fleet-scale position — enough to rebuild every wheel end on a machine, or to hold spares for a site running several identical units.

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.