Martin Marietta Corporation

Donald Mark Purcell

Robert Francis Larkin

A continuously variable hydrostatic transmission includes axially aligned input and output shafts journaled by a transmission housing and respectively coupled to a prime mover and a load. The input shaft drives a hydraulic pump unit, while a hydraulic motor unit is grounded to the transmission housing. A wedge-shaped swashplate is pivotally connected to the output shaft in operative position to accommodate pressurized hydraulic fluid exchanges between the pump and motor units. A controller is coupled to adjust the angular orientation of the swashplate relative to the output shaft axis and thus set the transmission ratio. A hydraulic circuit, connected into the hydraulic motor unit, is selectively operable to vent high and low fluid pressure sides of the swashplate to atmosphere, thus imposing a neutral transmission ratio condition regardless of the transmission ratio set by the controller.

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Pittsfield, MA, United States of America

Donald Mark Purcell