A hydrostatic transmission includes a pump running surface and a motor running surface connected by internal porting formed in a housing member. A valve is disposed in the housing and connects a sump formed by the housing and the internal porting. A trunnion includes a first arm engaged to a swash plate to rotate the swash plate to vary the output of the pump, and a second arm which rotates with the first arm, the second arm having an operative end that is capable of opening the valve to permit a hydraulic connection between the internal porting and the sump through the valve bore when the trunnion is rotated to a predetermined position.