Network optimization information:

Generally, the walking motor adopts high-speed motor plus planetary reducer or cycloidal pinwheel reducer, and some control circuits of hydraulic motor have certain characteristics. You can see in Figure 1 Travel motor The control circuit is equipped with a high pressure automatic transmission device. When the high speed is engaged, the circuit is connected to the manual transmission oil port to supply oil and push the transmission valve to move to the left to reduce the displacement of the motor; If the driving resistance increases, causing the oil pressure to rise to the set value, the oil pushes the shift valve to move to the right, making the motor displacement increase and the low-speed gear to increase torque. In this way, the motor can automatically change the position of the baffle according to the change of the travel resistance.

In addition to the adjustable speed of the motor, the motor control valve is mainly used to complete the control analysis of the motor.

Assuming that the oil is fed into port A, the motor rotates, and the motor control valve acts as follows:

Open the check valve, and the hydraulic oil enters the right chamber of the engine.

The hydraulic oil enters the balance valve through the orifice and moves to the left to connect the brake oil circuit, Traveling motor manufacturer Release the brake, and this action will also connect the oil circuit of motor port B.

The hydraulic oil enters the buffer piston chamber through the middle orifice of the safety valve and pushes the buffer piston to move to the left. If the system pressure exceeds the set pressure of the safety valve (10.2MPa), the safety valve will be opened immediately as a buffer.

If the engine overspeed (for example, when going downhill), the pump does not supply oil to the engine in time, the pressure at port A will decrease, and the balance valve will move to the right under the spring force, Variable speed hydraulic motor Close the oil return passage of the small engine, thus limiting the engine speed.

There are two safety valves with the same structure inside the walking control valve, which play an important buffer role in the starting and braking process of the excavator.