Importance

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Abstract

In a wheeled vehicle propelled by a hydrostatic transmission which has a variable displacement pump fluidly connected to a motor in a closed circuit for propulsion and a hydraulically-released brake for stopping the vehicle, a return to neutral and brake release circuit including: a system reservoir for holding fluid; a charge pump for drawing fluid from the reservoir and providing pressurized flow of same; a hydraulically-released brake operatively attached to the wheels of vehicle and the charge pump; a displacement control for providing differential pressure command signals to a servo piston for varying hydrostatic transmission displacement; a solenoid valve for interrupting the flow of fluid to the brake and displacement control, thus braking the vehicle and returning the variable pump to neutral; and a set of drain passages fluidly connecting the solenoid, displacement control and brake (through the solenoid) to the system reservoir so that the components may be immediately drained to allow the engagement of the hydraulically-released brake and return of the variable pump to neutral. Interrupting the fluid flow and draining the residual pressure, as described above, stops the vehicle quickly.

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First Claim