Function and working principle of balance valve of excavator walking motor

Posted on:2021-01-05       View:40

The function of the balance valve of the walking motor:


The balance valve prevents the machine from losing control due to motor rotation caused by external forces. When the machine travels downhill, the motor will rotate according to the weight of the machine. In this case, hydraulic oil larger than the supply volume of the control valve is discharged. The balance valve adjusts the throttling of the outlet pipeline according to the oil pressure on the inlet side.


The operating principle of the balance valve of the walking motor:


When walking on flat ground or uphill:

When operating the walking joystick, pressurized oil from the control valve flows into the oil port (PA). The pressurized oil pushes the suction safety valve (1) and flows from the inlet (MA) to the outlet (MB). Since the outlet oil circuit is closed by the suction safety valve (3) and the spool (2), the pressure on the inlet side increases. (The following picture)

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The pressurized oil on the inlet side flows into the cavity (A) from the orifices (B) and (C) of the spool (2). When the pressure in chamber (A) rises above the selection pressure of the balance valve, the spool (2) moves to the right. The outlet (MB) and the oil port (PB) are connected through the outlet channel (D), and the motor rotates. (The following picture)

                    企业微信截图_16098167026642.jpg

Principle when driving the machine on a slope:


When the machine travels downhill, the motor rotates by an external force, and the pressure on the inlet side is reduced. The pressure in the cavity (A) passing through the orifices (B) and (C) decreases. The pressure in chamber (A) drops below the selection pressure of the balance valve. Then, the reaction force of the spring (4) causes the spool (2) to return to the left, thereby restricting the outlet channel (D). The pressure on the outlet side increases and the motor generates rotational resistance. The spool (2) moves to a position where the gravity of the machine and the pressure on the inlet side are balanced with the pressure on the outlet (MB). Through the throttle outlet channel (D), the walking speed of the machine can be adjusted according to the pump displacement.(The following picture)

                    企业微信截图_1609817321721.jpg