Koyo JTEKT 30305DJR Tapered Roller Bearing

Koyo JTEKT 30305DJR Tapered Roller Bearing

The Koyo JTEKT 30305DJR is a precision metric tapered roller bearing designed to carry combined radial and axial loads efficiently. With a bore diameter of 25 mm, outer diameter of 62 mm, and an overall width of 18.25 mm (cone width 17 mm, cup width 13 mm), this bearing conforms to ISO dimension standards and is a direct interchange for equivalent metric tapered roller bearings from other manufacturers.

Design & Construction

Manufactured by JTEKT Corporation (formerly Koyo) – one of Japan’s leading bearing producers – the 30305DJ 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 inner ring (cone) and outer ring (cup), 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. The normal contact angle design provides a good balance between radial and axial load-carrying ability, making it the most versatile configuration for general-purpose applications. This is a DJ variant featuring a steep-angle cup (outer ring) design that shifts the effective load centre, providing enhanced axial load capacity in the direction opposing the standard cup face.

Performance

Rated for a basic dynamic load capacity of 39.8 kN and a static load capacity of 42.5 kN, this bearing delivers dependable combined-load support and long calculated service life under correct operating conditions. Permissible speeds reach 5,700 rpm with grease lubrication and 8,000 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.

Typical Applications

• Automotive wheel hubs, differentials, and transmission assemblies
• Gearboxes, reducers, and power transmission systems
• Machine tool spindles and precision equipment
• Agricultural and construction equipment
• Conveyor and material-handling systems
• Pumps, compressors, and rotating equipment
• Mining, quarrying, and heavy industrial machinery
• Railway and rolling stock components
• Steel and paper mill processing equipment
• General industrial and workshop machinery