DEVICE FOR CONTROLLING RUNNING OF WORKING CAR

PURPOSE:To enhance the working efficiency of a working car by providing a speed change control mechanism for automatically controlling an actuator to low speed or high speed side according to whether the detection pressure of the circuit pressure of a transmission driving circuit which connects a hydraulic pump and a hydraulic motor is above or below a set value. CONSTITUTION:When the circuit pressure of a transmission driving circuit 7a rises above a set value with the increase of a running driving load caused by working reaction a piston rod 19 slides to cylinder extension side because of the rise of the hydraulic pressure and turns off a control switch 16, and, when the circuit pressure of the circuit 7a becomes smaller than the set value with the decrease of the running driving load, the rod 19 slides to cylinder reduction side and the switch 16 reverts to its 'on' position by means of its self-recovering force. When the switch 16 reverts to its 'on' position electricity is transmitted to an operating circuit 15 and an auxiliary transmission valve 14 is switched to high speed side H so that an auxiliary transmission cylinder 12 is operated to high speed generation side. When the switch 16 is turned off transmission of electricity to the circuit 15 is stopped and the valve 14 is changed to low speed side L and the cylinder 12 is operated to low speed generation side.