Gm Global Technolgoy Operations, Inc.

Richard J Koenig

Carl A Lentz

Kenneth B Harmon

A multiratio powershift transmission with a shift control system having a manually selected roading phase and a working phase. The roading phase for vehicle drive permits manual selection of a normal automatic shift control mode providing automatic shifting between ratio drives in response to output speed and throttle for maintaining the engine driven input in a normal speed range for optimum economy at part throttle and optimum performance at full throttle, and a hold automatic shift control mode providing a manually selected ratio drive with hold automatic upshifts and normal automatic downshifts and inhibiting manual hold downshifts between ratio drives in response to output speed to limit engine driven input speed to a maximum speed range during overrun drive. The working phase for driving a works, such as a derrick, permits manual selection of the ratio drives to provide progressive output speed control in response to throttle, and provides hold upshifts and inhibited manual downshifts to limit engine speed to a maximum speed range.

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Carmel, IN, United States of America

Richard J Koenig