KoyoDouble Tapered Roller Bearing Cup 17-5/8″ OD 5-3/4″ W Inch HM259000 Section

Product Description

What this part is

A Koyo HM259010DS1 double tapered roller bearing cup — a one-piece outer race machined with two opposed tapered raceways. Outside diameter 17-5/8 in, width 5-3/4 in.

Decoding the designation

HM259010 is the ANSI/ABMA inch cup number of the HM259000 heavy section. The D suffix marks the double cup: two raceways in one ring rather than one. S1 is a Koyo internal design-variation code.

What these specs mean in practice

A double cup carries both rows of a back-to-back TDO arrangement in a single housing bore, so the two rows share one seat and one machined shoulder. Because the raceways are opposed, the completed arrangement takes thrust in both directions, and the row spacing — and therefore the moment stiffness — is fixed by the cup rather than set at assembly.

Published specifications

Bearing type: double tapered roller bearing cup (one-piece double outer race)Design units: inchOutside diameter: 17-5/8 in (447.68 mm)Width: 5-3/4 in (146.05 mm)Number of raceways: 2, opposedClosure: openMating cones: two HM259048

Quantity and configuration

Double cup only. It seats two cones, both Koyo HM259048. Sold as 1 Pc.

Fitting notes

The double cup presses into the housing bore against one square shoulder and locates both rows; the two cones mount separately on the shaft, and total endplay across the pair is set by the shaft nut or a spacer between the cone back faces.

Interchange guidance

The single HM259010 cup shares the outside diameter but carries one raceway and half the width, which makes it a related size rather than an interchange.