FAG24780/24720Single-row tapered roller bearing cone and cup assembly – 1.6250 in cone bore, 3.0000 in cup OD, 0.8750 in overall width, inch series, standard precision

Product Description

What this part is

The 24780/24720 is a complete single-row tapered roller bearing in the inch series, supplied as its two matched halves. The 24780 is the cone: the inner ring with its tapered roller complement and cage held captive on it. The 24720 is the cup, the separate outer race that the rollers run against. Cone bore is 1.6250 in (41.275 mm), cup outside diameter is 3.0000 in (76.200 mm), and overall width across the assembled pair is 0.8750 in (22.225 mm).

Decoding the designation

Inch-series tapered roller numbering pairs a cone number with its own cup number rather than encoding dimensions. 24780 is the cone part number and 24720 the cup part number, written as a fraction to show the matched pair. The absence of a precision suffix such as -3 marks standard precision, ANSI/ABMA Class 4. The absence of a D on either half means a single cone and a single cup rather than a double member.

Quantity and configuration

One cone and one cup, forming one complete bearing. Both halves are present.

What these specs mean in practice

The tapered roller geometry puts the roller, cone raceway and cup raceway apexes at a common point, so a single row carries heavy radial load together with thrust in one direction. Working thrust in the opposite direction comes from a second bearing, which is why tapered rollers are normally fitted as a mirrored pair — back-to-back for a stiff, widely spaced bearing span, or face-to-face where the effective load centres need to sit close together. Because the cone and cup separate, the two halves can be fitted from opposite ends of a housing and the running clearance set at assembly rather than being built into the bearing.

Setting and preload

Internal clearance on a tapered roller bearing is established by axial adjustment against the mating bearing, using a shim pack, a threaded nut or a spacer. End play, zero setting and light preload are all achievable from the same pair of bearings, so the mounted setting is a design choice rather than a bearing property.

Fitting notes

The cone is pressed onto the shaft seat with force applied to the cone back face, and the cup is pressed square into the housing bore against its shoulder. Rollers and cage stay with the cone throughout. Once both halves are seated, the assembly is rotated under light axial load while the setting is taken up so the rollers align on both raceways.

Interchange guidance

The 24780 cone and 24720 cup numbers are common inch-series references and cross directly to Timken 24780/24720, SKF 24780/24720, NTN 4T-24780/24720 and Koyo 24780/24720. Related sizes on the same cone: 24780/24721 uses a wider cup for a 1.000 in overall width, and 24780-2 is the same cone in Timken Class 2 precision. Both are different parts rather than substitutions.