Patent ID: 6209675
Filing Date: 2001-04-03
Classification: F16H

Abstract:
A travel drive apparatus for a hydraulic drive work vehicle including a travel hydraulic pump driven by a power of an engine; a hydraulic motor that receives discharged oil from the travel hydraulic pump and causes a vehicle to travel; a travel changeover valve that receives the discharged oil from the travel hydraulic pump, supplies the discharged oil to the hydraulic motor and discharges return oil from the hydraulic motor to a tank, wherein the apparatus comprises:acceleration means for controlling an engine rotational speed;operation means for selecting vehicle forward travel, stop, or reverse travel;the travel changeover valve being adapted for switching the discharged oil supplied from the travel hydraulic pump to the hydraulic motor by receiving a signal from the operation means, and controlling vehicle forward travel, stop, and reverse travel;a relief valve disposed between the travel changeover valve and the hydraulic motor, for regulating pressure for controlling the hydraulic motor when the vehicle is decelerated; andpressurizing means for raising set pressure at the relief valve controlling the hydraulic motor when an engine rotational speed is increased and lowering the set pressure at the relief valve controlling the hydraulic motor when the engine rotational speed is decreased, while switching the vehicle from forward travel to reverse travel, or from reverse travel to forward travel.