Hydraulic balance valve Excavator hydraulic cylinder spool CXHA-XBN

Balance valve structure and working principle

The hydraulic balance valve allows the oil to flow freely from port 2 to port 1. We can see from the structure diagram at the top of the figure below that when the oil pressure of port 2 is higher than that of port 1, the spool of the green part moves towards port 1 under the drive of liquid pressure, and the check valve is opened, and the oil can flow freely from port 2 to port 1.

The flow from port 1 to port 2 is blocked until the pressure of the pilot port reaches a certain value and the blue spool is moved to the left to open the valve port so that the oil can flow from port 1 to port 2.

The port closes when the pilot pressure is insufficient to open the blue spool. The flow from port 1 to port 2 is cut off.
Hydraulic balance valve working principle:
Balancing circuit with unidirectional sequence valve. Adjust the sequence valve so that the product of its opening pressure and the acting area of the lower chamber of the hydraulic cylinder is slightly greater than the gravity of the vertical moving parts. When the piston goes down, because there is a certain back pressure on the oil return circuit to support the gravity load, the piston will fall smoothly only when the upper part of the piston has a certain pressure; When the reversing valve is in the middle position, the piston stops moving and does not continue down. The sequence valve here is also called the balance valve. In this balance loop, the sequence valve is adjusted after the pressure is set. If the workload gets smaller. The pressure of the pump needs to be increased, which will increase the power loss of the system. Due to the internal leakage of the sequence valve and the reversing valve of the slide valve structure, it is difficult to make the piston stop statically in any position for a long time, which will cause the gravity load device to slide. Therefore, this circuit is suitable for the work load is fixed and the hydraulic cylinder piston locking positioning requirements are not high.