Hardened washer for National Crane 900

The hardened washer part number 978502 is a flat, circular mechanical component positioned under the head of a bolt or a nut. Its function is to distribute the tightening load over a broader surface, which protects the surface of the joined components and lowers the probability of the connection loosening due to dynamic loads or vibrations. The hardened specification indicates the component has undergone heat treatment to manage its hardness and resistance to deformation during assembly.

This component is compatible with the Manitowoc 600E and the National Crane 900 crane models. It is utilized in various structural assemblies, including the boom structure, slewing base, and outrigger systems where high-load bolted connections are required to maintain structural stability. Proper installation of this washer ensures that the intended preload of the bolt is maintained within the assembly.

In heavy machinery, hardened washers are used to prevent the fastener from sinking into the material surface when high torque is applied. By providing a stable bearing surface, they help ensure consistent tension across the joint, which is a standard requirement for maintaining the safety and structural performance of crane components during lifting operations.