ASTM D4693-07(R2021) pdf free download

ASTM D4693-07(R2021) pdf free download.Standard Test Method for Low-Temperature Torque of Grease-Lubricated Wheel Bearings
1. Scope
1.1 This test method covers the determination of the extent to which a test grease retards the rotation of a specially- manufactured, spring-loaded, automotive-type wheel bearing assembly when subjected to low temperatures. Torque values, calculated from restraining-force determinations, are a measure of the viscous resistance of the grease. This test method was developed with greases giving torques of less than 35 N·m at −40 °C. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 WARNING—Mercury has been designated by many regulatory agencies as a hazardous substance that can cause serious medical issues. Mercury, or its vapor, has been dem- onstrated to be hazardous to health and corrosive to materials. Use Caution when handling mercury and mercury-containing products. See the applicable product Safety Data Sheet (SDS) for additional information. The potential exists that selling mercury or mercury-containing products, or both, is prohibited by local or national law. Users must determine legality of sales in their location. 1.4 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 appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.5 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
3. Terminology
3.1 Definitions:3.1.1 automotive wheel bearing grease, n—a lubricating grease specifically formulated to lubricate automotive wheel bearings at relatively high grease temperatures and bearing speeds. D3527 3.1.2 lubricant, n—any material interposed between two surfaces that reduces the friction or wear between them. D4175 3.1.3 lubricating grease, n—a semi-fluid to solid product of a dispersion of a thickener in a liquid lubricant. 3.1.3.1 Discussion—The dispersion of the thickener forms a two-phase system and immobilizes the liquid lubricant by surface tension and other physical forces. Other ingredients are commonly included to impact special properties. D217 3.1.4 thickener, n—in lubricating grease, a substance com- posed of finely-divided particles dispersed in a liquid lubricant to form the product’s structure. 3.1.4.1 Discussion—The solid thickener can be fibers (such as various metallic soaps) or plates or spheres (such as certain non-soap thickeners) which are insoluble or, at the most, only very slightly soluble in the liquid lubricant. The general requirements are that the solid particles be extremely small, uniformly dispered, and capable of forming a relatively stable, gel-like structure with the liquid lubricant.
6. Apparatus
6.1 Low-Temperature Wheel Bearing Torque Apparatus, 6,7 illustrated in Fig. 1. N OTE 1—Several apparatus configurations are available, differing mainly in the drive system. For example, with large cold chambers, a unitized apparatus (see Fig. 1) can be used totally within the cold chamber. With small cold chambers, the drive system can be mounted externally and only the test unit subjected to low temperature. Regardless of the exact configuration, the essential apparatus consists of a 1/3 hp electric motor connected to a gear reducer by means of a timing belt and pulleys, which drive a specially-manufactured spindle-bearings-hub assembly equipped with a spring-loading mechanism. For apparatus contained totally within the cold chamber, the drive system should be prepared by replacing the grease in the motor bearings with a suitable low-temperature grease (<1 N·m torque at −40 °C), such as one meeting the requirements of Specification MIL-G-10924F or similar, and the lubricant in the gear reducer should be replaced with a suitable low-temperature (< −50 °C pour point) worm-gear lubricant. 7,8 In addition, if not already so- equipped, large-diameter (152 mm), narrow-width (13 mm) timing pul- leys and a suitable timing belt should be used.