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Experience | Daniel J. Cowley | Sundstrand Corporation



Sundstrand was manufacturing the Responder hydromechanical transmission for use in large trucks. It was designed as a replacement for the normally used 10-speed manual gearbox. The transmission was most useful for in-city and construction work service where slower stop-and-go driving makes an automatic transmission attractive.

The Responder was capable of handling 250 hp, and weighs about 725 pounds. It had two modes of operation: (1) a straight hydrostatic mode for low speeds, and (2) a power-split mode for higher speeds. (At the lower end of the power-split mode, there was power recirculation through the hydrostatic path.)

Full-power efficiency varies from about 70 to 93 percent.


For additional information, refer to the following papers:


1. P. E. Troin and V. G. Gostomski, "Application Considerations with the Cummins Sundstrand DMT-25 Hydromechanical Transmission," SAE Paper 750732, 1975.


2. W. A. Ross, "Designing a Hydro-mechanical Transmission for Heavy Duty Trucks," SAE Paper 720725, 1972.


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