Timken24720DDouble Tapered Roller Bearing Cup, 3 in. Outside Diameter, 1.5625 in. Width, Two-Row TDO Imperial Inch Series

Product Description

What this part is

A double tapered roller bearing cup in the 24720D size — a one-piece outer ring carrying two opposed tapered raceways, the outer half of a two-row TDO (tapered double outer) bearing. Cup only. It is mated with two cones; the published cone is the Timken 24780, used one per row.

Decoding the designation

24720 is the inch-series cup number and the D suffix marks it as a double cup rather than a single. That distinction is dimensional as well as descriptive: the single 24720 cup is 0.875 in. wide, while the 24720D is 1.5625 in. wide because it holds two raceways in one ring. The alternate written form is 24720-D. Cup numbers in the 247xx block pair with cone numbers in the same block, which is why the mating cone is a 24780.

What these specs mean in practice

A TDO arrangement puts both rows inside a single outer ring, so the bearing takes thrust in both directions and carries an overturning moment on a short mounting length. Because the two raceways are ground in one piece, their spacing and angle relationship is fixed at manufacture and the row-to-row setting is controlled by the cup rather than by shimming the housing — the practical advantage over two single-row bearings mounted back to back. The load lines diverge outward from the cup centre, which gives a wide effective bearing spread inside a compact envelope. That suits wheel hubs, idler rolls, sheaves and pinion positions where the housing bore is short and both axial directions are loaded.

Published dimensions and assembly data

Double cup outside diameter: 3.0000 in. (76.2 mm)
Double cup width: 1.5625 in. (39.688 mm)
Number of raceways in the cup: 2, one-piece outer ring
Mating cone 24780: bore 1.6250 in. (41.275 mm), cone width 0.906 in.
Complete 24780–24720D TDO assembly: 41.275 mm bore × 76.2 mm outside diameter × 49.21 mm overall width (T = 1.9375 in.)
Dynamic radial rating of the complete 24780–24720D TDO assembly: 132 kN

Quantity and configuration

One double cup, sold individually. Two rows, straight outside diameter, no flange.

Fitting notes

The double cup presses into the housing bore and is driven on the backface with a flat tool contacting the whole ring. A TDO build normally seats the cup first and then enters a cone from each end, with the assembly clamped on the shaft; the housing bore takes the cup as a light press and the cup usually needs no shoulder on both sides because the two rows locate each other.

Interchange guidance

24720D interchanges directly across Timken, SKF, FAG, NTN and Koyo because the inch-series number and the D suffix define the geometry. The plain 24720 single cup is a related size, not a substitute: it is 0.875 in. wide with one raceway and belongs to a single-row TS bearing. The 24720D also appears in a published TDO assembly with the NA24776SW cone.