Manual displacement control for hydrostatic transmissions and method of

Abstract

A control assembly, for hydrostatic transmissions equipped with a pump and a valve element to control flow of hydraulic fluid to the pump, including a pump body member having a cavity with a movable valve element mounted in the body and connected to a source of pressurized hydraulic fluid and having a neutral position. A cover member is secured over the body member and a control shaft having interior and exterior ends extends therethrough. A manual control lever is mounted on the exterior end of the control shaft, and a cam plate with an elongated cam slot therein is secured to the interior end of the control shaft. Linkage, including an arm pivotally connected to the pump body and having a first upstanding pin thereon, interconnects the pump and the valve element. A second arm pivotally mounted on the first upstanding pin and a second upstanding pin mounted offset from the first upstanding pin on the second arm interconnects the control lever and valve element via control shaft and cam plate. A detent portion located in the cam slot opposite the second upstanding pin defines a concurrent neutral position for the pin. A resilient torque spring in the cover yieldingly holds the control shaft, the control lever, the cam plate in the concurrent neutral position and simultaneously holds the valve element and the remainder of the linkage in a neutral position. A method of assembling this control assembly is also disclosed.