Steering device for wheel loader

A steering device for a wheel loader in which a front frame and a rear frame are pivotably coupled in a horizontal direction, the steering device comprising:

• a handle operated by rotation for steering;
• a lever operated by tilting for steering;
• a steering cylinder configured to pivot the front frame in relation to the rear frame by expansion and contraction;
• a steering valve configured to control a supply direction of operating fluid to the steering cylinder with pilot hydraulic pressure;
• a pump configured to supply operating fluid to the steering cylinder via the steering valve;
• a handle control valve configured to supply pilot hydraulic pressure in order to control the supply direction to the steering valve according to a rotation operation of the handle;
• a lever electromagnetic control valve configured to supply pilot hydraulic pressure in order to control the supply direction to the steering valve according to a tilting operation of the lever;
• a handle prioritization valve configured to shut off the pilot hydraulic pressure supplied from the lever electromagnetic control valve to the steering valve according to a differential pressure or an absolute pressure in a hydraulic circuit produced due to operating fluid flowing through the handle control valve when the handle is operated;
• a left pilot oil passage provided between the handle control valve and the steering valve;
• and
• a right pilot oil passage provided between the handle control valve and the steering valve;
• and
• a return oil passage configured to guide return oil from the steering valve to a tank via the handle control valve;
• output ports of the lever electromagnetic control valve being connected to the left and right pilot oil passages;
• and
• the handle prioritization valve including:
• a throttle provided in the return oil passage between the handle control valve and the tank;
• and
• a prioritization valve body provided between the output ports of the lever electromagnetic control valve and the left and right pilot oil passages, the prioritization valve body including
• a communication stage that allows communication between the output ports of the lever electromagnetic control valve and the left and right pilot oil passages, and
• a shutoff stage that shuts off communication between the output ports of the lever electromagnetic control valve and the left and right pilot oil passages;
• the prioritization valve body being switched to the shutoff stage when a differential pressure is produced on either side of the throttle, and the prioritization valve body being switched to the communication stage when no differential pressure is produced on either side of the throttle.