Koyo 25577/25523 Tapered Roller Bearing

Koyo 25577/25523 Tapered Roller Bearing

The Koyo 25577/25523 is a precision imperial (inch-series) tapered roller bearing assembly consisting of cone (inner ring) 25577 and cup (outer ring) 25523. Designed to carry combined radial and axial loads efficiently, this bearing features a bore diameter of 42.875 mm, outer diameter of 82.93 mm, and an overall assembly width of 26.988 mm (cone width 25.4 mm, cup width 22.225 mm). As an inch-series bearing, it is a direct interchange for equivalent imperial tapered roller bearings from other manufacturers including Timken, NACHI, and NTN.

Design & Construction

Manufactured by Koyo (JTEKT Corporation) – one of Japan’s leading bearing producers – the 25577/25523 is precision-ground from high-carbon chromium bearing steel (AISI 52100 / JIS SUJ2), heat-treated to achieve optimum hardness and fatigue resistance. The tapered roller design features conical raceways on both the cone (inner ring) and cup (outer ring), with tapered rollers running between them. This geometry allows the bearing to support combined radial and axial loads simultaneously, with the contact angle determining the ratio of axial to radial load capacity. Imperial-series tapered roller bearings are the most widely used tapered roller configuration worldwide, with extensive application in automotive, agricultural, and general industrial equipment.

Typical Applications

• Automotive wheel hubs, differentials, and transmission assemblies
• Agricultural machinery and equipment
• Construction and earthmoving equipment
• Gearboxes, reducers, and power transmission systems
• Conveyor and material-handling systems
• Pumps, compressors, and rotating equipment
• Mining, quarrying, and heavy industrial machinery
• Trailer axles and suspension components
• Marine and boat trailer applications
• General industrial and workshop machinery