NACHI NU256 Cylindrical Roller Bearing

NACHI NU256 Cylindrical Roller Bearing

The NACHI NU256 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 280 mm, outer diameter of 500 mm, and a width of 80 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 NU256 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.

Performance

Rated for a basic dynamic load capacity of 1140.0 kN and a static load capacity of 1680.0 kN, this bearing delivers exceptional radial load-carrying ability and long calculated service life under correct operating conditions. Permissible speeds reach 1,200 rpm with grease lubrication and 1,400 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