Travel motor hydraulic control system for a construction machine

Travel motor hydraulic control system for a construction machine having a plurality of hydraulic pumps which supply individually pressurized fluid for a plurality of hydraulic travel motors and a plurality of flow control valves which control the flow rate of the pressurized fluid to be supplied to the motor during an ordinary work comprising;

• a pilot operated shut off valve disposed between a left and right hand travel motor drive circuit,
• a position sensor connected to an operating control valve for detecting a lever stroke thereof;
• a pressure sensor for detecting a fluid pressure in the respective travel motor circuit disposed therein;
• a controller including a first storage unit and second storage unit, the first storage unit storing a function for determining if or not the vehicle is traveling straight, the second storage unit storing a function for determining if or not the vehicle is traveling up a slope, the controller receives the control signal representative of the travel control lever stroke sensed by the position sensor and a control signal detected by the pressure sensor, determines if the vehicle is traveling up a slope, and transmits a command signal to a solenoid operated valve to move the pilot operated shut off valve toward the valve-closing position, thereby the travel hydraulic motors are individually supplied the pressurized fluid from the hydraulic pumps.