This specification deals with one-wear, two-wear, and multiple-wear wrought carbon steel wheels for locomotives and cars. The classes of steel wheels according to passenger car service covered here are: Class L, which are for high speed services with more severe braking conditions than other classes and light wheel loads; Class A, which are for high speed services with more severe braking conditions, but moderate wheel loads; Class B, which are for high speed services with severe braking conditions and heavier wheel loads; Class C (1), which are for services with light braking conditions and heavier wheel loads; and Class C (2), which are for services with heavier braking conditions where off-tread brakes are employed. Class B and C wheels shall be used for freight cars in interchange service, and are recommended for use on locomotives. Wheels shall be treated by rim-quenching and shot peening, and shall be finished by rough boring and machining. Heat analysis and rim hardness measurement procedures shall be performed to evaluate the conformance of wheel specimens with chemical composition and Brinell hardness requirements, respectively. Materials shall also go through nondestructive ultrasonic and magnetic particle examinations. Finally, customary product marking procedures shall be followed.

1.1 This specification covers one-wear, two-wear, and multiple-wear wrought carbon steel wheels for locomotives and cars, designated Classes L, A, B, and C, heat-treated, wheels.

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

1.2.1 Class B or C wheels shall be used for freight cars in interchange service.

1.2.2 Class B or C wheels are recommended for use on locomotives.

1.2.3 For passenger car service, the various classes are intended generally as follows:

1.2.3.1 Class L—High speed with more severe braking conditions than other classes and light wheel loads.

1.2.3.2 Class A—High speed with more severe braking conditions, but moderate wheel loads.

1.2.3.3 Class B—High speed service with severe braking conditions and heavier wheel loads.

1.2.3.4 Class C—(1) Service with light braking conditions and heavier wheel loads.

1.2.3.5 Class C—(2) Service with heavier braking conditions where off-tread brakes are employed.

1.3 The use of two-wear wheels is recommended for freight car service.

1.4 Supplementary requirements included in Specification A 788/A 788M may be specified by the purchaser for forgings ordered to this specification.

1.5 The values stated in either inch-pound units or SI (metric) units are to be regarded separately as the standard. Within the text and tables, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.

1.6 Unless the order specifies the applicable “M” specification designation, the material shall be furnished to the inch-pound units

1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.