Koyo 387AS/382A Tapered Roller Bearing

Koyo 387AS/382A Tapered Roller Bearing

The Koyo 387AS/382A is a precision imperial (inch-series) tapered roller bearing assembly consisting of cone (inner ring) 387AS and cup (outer ring) 382A. Designed to carry combined radial and axial loads efficiently, this bearing features a bore diameter of 57.15 mm, outer diameter of 96.838 mm, and an overall assembly width of 21 mm (cone width 21.946 mm, cup width 15.875 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 387AS/382A 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.

Performance

Rated for a basic dynamic load capacity of 101.0 kN and a static load capacity of 101.0 kN, this bearing delivers dependable combined-load support and long calculated service life under correct operating conditions. Permissible speeds reach 3,900 rpm with grease lubrication and 5,200 rpm with oil lubrication. The separable design – where the cone (inner ring with roller and cage assembly) and cup (outer ring) can be mounted independently – simplifies installation, allows adjustment of internal clearance or preload, and facilitates maintenance. Imperial tapered roller bearings are fully interchangeable between manufacturers of the same designation, allowing flexibility in sourcing and replacement.

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