1.1 本规范涵盖机车和车辆用一磨损、二磨损和多磨损锻造碳钢车轮，指定为L、A、B和C级热处理车轮。 1.2 各种类别的服务如下: 1.2.1 在互通式立交服务中，货车应使用B级或C级车轮。 1.2.2 建议在机车上使用B级或C级车轮。 1.2.3 对于客车服务，各种级别通常如下所示: 1.2.3.1 L类 -高速，制动条件比其他级别更为恶劣，车轮负载较轻。 1.2.3.2 A类 -高速，制动条件更为恶劣，但车轮负载适中。 1.2.3.3 B类 -具有严重制动条件和较重车轮负载的高速服务。 1.2.3.4 C类 —( 1. )在制动条件较轻、车轮负载较重的情况下使用。 1.2.3.5 C类 —( 2. )在使用非踏面制动器的较重制动条件下使用。 1.3 提供了补充要求，以供买方需要额外测试或额外限制时使用。规范中包含的补充要求 A788/A788米 对于按照本规范订购的锻件，也可由买方指定。任何补充要求仅在采购订单中有规定时适用。 1.4 以国际单位制或英寸磅单位表示的数值应单独视为标准。在文本和表格中，国际单位制单位显示在括号中。 每个系统中规定的值可能不是精确的等效值；因此，每个系统应独立于其他系统使用。将两个系统的值组合在一起可能会导致不符合标准。 1.5 除非订单规定了适用的“M”规格名称，否则材料应按英寸磅单位提供。 1.6 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。

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 Supplemental requirements are provided for use where additional testing or additional restrictions are required by the purchaser. Supplementary requirements included in Specification A788/A788M may also be specified by the purchaser for forgings ordered to this specification. Any supplemental requirements apply only when specified in the purchase order. 1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text and tables, the SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard. 1.5 Unless the order specifies the applicable “M” specification designation, the material shall be furnished to the inch-pound units. 1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.