atft0.jpg (34672 bytes)Automatic Transmission Fluids Testing

The automatic transmission fluids (ATFs) used in today's cars are highly specialized products largely responsible for the shift quality and mechanical durability of automatic transmissions.

ATFs function as gear and bearing surface lubricants, power transmission media, hydraulic control fluids, and heat transfer media. With so much required of ATFs, the need for comprehensive fluid quality testing is critical. Qualification testing involves approximately 20 specialized procedures, including chemical benchwork, oxidation resistance, friction durability, simulated vehicular cycle, and in-car performance testing.

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The sprag clutch over-running wear test (SCOWT) apparatus evaluates the lubricant properties of various fluids by determining weight loss on specific sprag elements.

Southwest Research Institute (SwRI) has been the leading independent test facility for ATFs and other hydraulic power transfer fluids since the 1950s. The SwRI Fuels and Luricants Research Division conducts qualification tests for General Motors DEXRONŽ-III, Ford MERCONŽ and MERCONŽ V, Allison C-4, TES-295, and CaterpillarŽ TO-4 fluids. SwRI is also actively involved in test development for the next generation for service fill ATFs of GM and Ford vehicles. The Institute's involvement in automatic transmission fluids is not limited to evaluation, but also includes development of new test procedures.

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Friction durability tests, run to vehicle manufacturer test procedures on SAE No. 2 friction test machines, establish friction characteristics and fluid durability after repeated cycling and continual operation.

SwRI provides an independent, unbiased site where auto manufacturers and additive companies can share information beneficial to both.

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Vehicle performance evaluations are conducted on SwRI's on-site track to determine the effects of fluid properties on automatic transmission shift characteristics.

A 300-hour test, run on an electric motor-driven Hydra-Matic 4L60-E automatic transmission, is used to determine oxidation resistance, thermal stability, and corrosion protection characteristics of fluids.

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This brochure was published in November 1999. For more information about automatic transmission fluids testing, contact Matt Jackson, Manager, Phone (210) 522-6981, Fuels and Lubricants Research Division, Southwest Research Institute, P.O. Drawer 28510, San Antonio, Texas 78228-0510.

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