NACHI NJ308 Cylindrical Roller Bearing

NACHI NJ308 Cylindrical Roller Bearing

The NACHI NJ308 is a precision cylindrical roller bearing (NJ – Inner Ring One Integral Rib) designed for high radial load capacity at moderate to high speeds. With a bore diameter of 40 mm, outer diameter of 90 mm, and a width of 23 mm, this bearing conforms to ISO dimension standards and is a direct interchange for equivalent cylindrical roller bearings from other manufacturers.

Design & Construction

Manufactured by NACHI – one of Japan’s leading bearing producers – the NJ308 is precision-ground from high-carbon chromium bearing steel (AISI 52100 / JIS SUJ2), heat-treated to achieve optimum hardness and fatigue resistance. The line contact between rollers and raceways provides a much larger contact area than ball bearings of the same size, resulting in substantially higher radial load capacity. The NJ design features an inner ring with one integral rib and an outer ring with two ribs. This configuration can carry radial loads and limited axial loads in one direction via the inner ring rib, while allowing axial displacement in the opposite direction.

Performance

Rated for a basic dynamic load capacity of 58.5 kN and a static load capacity of 57.0 kN, this bearing delivers exceptional radial load-carrying ability and long calculated service life under correct operating conditions. Permissible speeds reach 6,700 rpm with grease lubrication and 8,500 rpm with oil lubrication. Cylindrical roller bearings are inherently separable – the inner ring with roller and cage assembly can be mounted independently from the outer ring, simplifying installation and maintenance in many applications.

Typical Applications

• Electric motors and generators
• Gearboxes, reducers, and transmission assemblies
• Pumps, compressors, and turbines
• Machine tool spindles and precision equipment
• Rolling mill and heavy industrial machinery
• Wind turbine drivetrain components
• Railway axlebox and traction motor bearings
• Mining, quarrying, and construction equipment
• Paper and steel mill processing equipment
• General industrial and workshop machinery