NACHI NU308EG Cylindrical Roller Bearing

NACHI NU308EG Cylindrical Roller Bearing

The NACHI NU308EG is a precision cylindrical roller bearing (NU – Inner Ring Two Integral Ribs) 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 NU308EG 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 NU design features an inner ring with two integral ribs and a plain outer ring. This configuration allows axial displacement of the shaft relative to the housing within the bearing, accommodating thermal expansion. It carries radial loads only. This is an enhanced capacity (EG) variant featuring an optimised roller complement, modified internal geometry, and a polyamide (nylon) cage. The polyamide cage reduces weight, allows a higher roller complement, lowers friction and noise, and provides superior performance at high speeds compared to pressed steel cages. These enhancements deliver significantly higher dynamic and static load ratings compared to the standard version.

Performance

Rated for a basic dynamic load capacity of 83.0 kN and a static load capacity of 81.5 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 8,000 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