The traveling motor is equipped with a high pressure automatic variable device. When the high-speed gear is put up, the circuit takes over the oil port of the transmission speed to oil, and pushes the transmission valve to move left, so that the motor becomes a small displacement. If the driving resistance increases and the oil pressure rises to the set value, the oil pushes the speed change valve to the right, and the motor automatically changes to the large-displacement low-speed gear to increase the torque. Therefore, the motor can automatically change gear with the change of walking resistance.
In addition, the control of the motor is mainly completed by the motor control valve, the following combined with the structural schematic analysis of its working principle.
Assume that port A feeds oil, the motor rotates, and the motor control valve operates as follows:
(1) Open the check valve, and the hydraulic oil enters the right chamber of the motor.
(2) The hydraulic oil enters the balance valve through the throttle hole, and moves it to the left to connect the brake oil circuit, so that the brake is loosened, and this action also connects the oil return circuit of the motor B port.
(3) The hydraulic oil enters the buffer piston cavity through the middle throttle hole of the safety valve and pushes the buffer piston to the left side. If the system pressure exceeds the set pressure of this safety valve (10.2MPa), the safety valve will be opened in an instant to play a buffer role.
(4) If the motor is speeding (such as downhill), the pump is too late to supply oil, so that the pressure of the A port is reduced, the balance valve moves to the right under the action of the spring force, and the oil return channel of the small motor is closed, thus limiting the speed of the motor.
Use Cases: