This specification covers wrought steel wheels for electric railway service designated Class U, untreated, and Classes L, A, B, and C, heat treated.

The service for which the various classes are intended generally is as follows:

Class U—General service where an untreated wheel is satisfactory.

Class L—High-speed service with more severe braking conditions and light wheel loads.

Class A—High-speed service with heavy braking conditions, but with moderate wheel loads.

Class B—High-speed service with heavy braking conditions and heavier wheel loads.

Class C—Service with light braking conditions and high wheel loads, or service with heavier braking conditions where off-tread brakes are employed.

NOTE 1—The values stated in inch-pound units are to be regarded as the standard.