This type of motor does not have a valve that calculates the balance function. When the rotation speed is greater than the hydraulic oil supply of the motor, in order to prevent cavitation caused by insufficient oil, a supplementary valve is used to supplement the lack of oil.
When the hydraulic motor of the excavator drives the pump to work, the oil port of the hydraulic oil tank cannot guarantee the required supply pressure, and the supplementary valve provides immediate help. The boosted pressure acts on the supply port of the hydraulic motor through the supplementary valve.
The compressed oil enters port B, and the motor rotates counterclockwise.
If the plunger of the main control valve moves to the middle position, the oil in the motor is discharged through the left relief valve, and the discharged oil flows into the motor through the right replenishment valve, which prevents cavitation of the motor.
