1.1 本试验方法涵盖在高温下操作时用于重型手动变速器的液体的热稳定性。 1.2 当变速箱在高档域和低档域之间连续循环时，润滑剂性能通过可在不发生同步故障的情况下执行的换档循环次数来测量。 1.3 尚未建立测试结果与卡车变速箱服务的相关性。然而，该程序已被证明能够适当分离两种变速箱润滑油，在一家制造商的卡车上显示出满意和不满意的现场性能。 1.4 由于程序的改进、零件或试剂的过时等原因，可能需要对本试验方法进行更改。这些变更将纳入ASTM测试监测中心（TMC）发布的信息函中。测试方法将进行修订，以显示所有信件的内容。 1.5 以英寸-磅为单位的数值应视为标准值。括号中给出的值是到国际单位制的数学转换，仅供参考，不被视为标准值。 1.5.1 例外情况- 如果材料、产品或设备仅以英寸-磅为单位，则省略国际单位。 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）。本标准的用户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 本试验方法安排如下: 部分 范围 1. 参考文件 2. 术语 3. 试验方法总结 4. 意义和用途 5. 仪器 6. 测试变速器 6.2 变速器支架 6.3 油循环系统 6.4 回油孔 6.5 空气压力控制 6.6 驱动系统 6.7 仪器仪表 6.8 热电偶放置 6.9 试剂和材料 7. 安全 8. 仪器的准备 9 零件的清洁 9.1 装配 9.2 标定 10 变速箱和试验台校准 10.1 参考油 10.2 参考油测试频率 10.3 仪器校准 10.4 换档时间校准 10.5 操作程序 11 系统冲洗和充电 11.1 测试操作 11.2 关闭程序 11.3 变速箱拆解 11.4 测试结果的确定 12 故障标准 12.1 换档拨叉磨损 12.2 测试有效性确定 12.3 汇报 13 精度和偏差 14 关键词 15 测试有效性计算和限制 附件A5 HTCT测试报告表和数据字典 附录A6 手动变速器循环耐久性试验零件检查和磨损测量 附件A7 1.8 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）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》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 本试验方法用于评估汽车手动变速器油液的热不稳定性，这会导致同步器性能恶化。 5.2 该试验方法也可用于变速箱和齿轮润滑剂的其他规范和分类，例如: 5.2.1 （PG-1的最终API名称）， 5.2.2 军用规范MIL-L-2105， 5.2.3 SAE信息报告J308轮轴和手动变速器润滑油，以及 5.2.4 Mack卡车GO-H齿轮润滑剂规格。

1.1 This test method covers the thermal stability of fluids for use in heavy duty manual transmissions when operated at high temperatures. 1.2 The lubricant performance is measured by the number of shifting cycles that can be performed without failure of synchronization when the transmission is operated while continuously cycling between high and low range. 1.3 Correlation of test results with truck transmission service has not been established. However, the procedure has been shown to appropriately separate two transmission lubricants, which have shown satisfactory and unsatisfactory field performance in the trucks of one manufacturer. 1.4 Changes in this test method may be necessary due to refinements in the procedure, obsolescence of parts, or reagents, and so forth. These changes will be incorporated by Information Letters issued by the ASTM Test Monitoring Center (TMC). The test method will be revised to show the content of all the letters, as issued. 1.5 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.5.1 Exception— When materials, products, or equipment are available only in inch-pound units, SI units are omitted. 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 test method is arranged as follows: Section Scope 1 Referenced Documents 2 Terminology 3 Summary of Test Method 4 Significance and Use 5 Apparatus 6 Test Transmission 6.2 Transmission Mounts 6.3 Oil-Circulating System 6.4 Oil Return Hole 6.5 Air Pressure Controls 6.6 Drive System 6.7 Instrumentation 6.8 Thermocouple Placement 6.9 Reagents and Materials 7 Safety 8 Preparation of Apparatus 9 Cleaning of Parts 9.1 Assembly 9.2 Calibration 10 Transmission and Test Stand Calibration 10.1 Reference Oils 10.2 Reference Oil Test Frequency 10.3 Instrumentation Calibration 10.4 Shift Time Calibration 10.5 Operating Procedure 11 System Flush and Charge 11.1 Test Operation 11.2 Shut-Down Procedure 11.3 Transmission Disassembly 11.4 Determination of Test Results 12 Failure Criteria 12.1 Shifter Fork Wear 12.2 Test Validity Determination 12.3 Report 13 Precision and Bias 14 Keywords 15 Test Validity Calculations and Limits Annex A5 HTCT Test Report Forms and Data Dictionary Annex A6 Manual Transmission Cyclic Durability Test Parts Inspection and Wear Measurements Annex A7 1.8 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. ====== Significance And Use ====== 5.1 This test method is used to evaluate automotive manual transmission fluids for thermal instability, which results in deterioration of synchronizer performance. 5.2 This test method may also be utilized in other specifications and classifications of transmission and gear lubricants such as the following: 5.2.1 (final API designation of PG-1), 5.2.2 Military Specification MIL-L-2105, 5.2.3 SAE Information Report J308 Axle and Manual Transmission Lubricants, and 5.2.4 Mack Truck GO-H Gear Lubricant Specification.