The only difference between a hydraulic directional valve and an electromagnetic directional valve is the force that pushes the valve core to move. The former is the hydraulic pressure of the pressure oil, and the latter is the suction force of the electromagnet. The specific fault analysis and troubleshooting methods of hydraulic directional valves are as follows.
Fault: (1) No reversal or poor reversal
Cause: The pressure of the control oil that pushes the valve core to move is insufficient, or the control oil pressure is sufficient, but the oil return of the control oil chamber at the other end of the valve core is not smooth. The reason for the poor return may be dirt blockage, insufficient opening volume, or high return oil back pressure. These situations cause the valve core of the hydraulic reversing valve to be unable to move or move inflexibly, thus failing to reversing or causing poor reversal.
Solution: 1. Appropriately increase the pressure of the control oil. The control oil pressure range of the 6.3 MPa series of hydraulic reversing valves is 0.3-6.3 MPa, and the control oil pressure range of the 32 MPa series of valves is 1-32 MPa. If the pressure is lower than the minimum value, the hydraulic valve cannot be reversed.
2. For hydraulic reversing valves such as M, H, and K types that are in the unloading state in the middle position, if the control oil is taken from the system, a back valve must be installed on the return oil line, and the back adjustment value must be large enough to provide sufficient pressure control oil to make the raft core move and reverse.
3. If the return spring is broken and the direction cannot be reversed, the return spring must be replaced.
4. If the valve cover is installed in the wrong direction during disassembly and repair, the control oil will not enter or return, resulting in the inability to switch. At this time, the valve cover assembly direction should be corrected, and the control oil port on the valve cover should be directly opposite the control oil port on the end face of the valve body: For those where the control oil is introduced from the top cover plate, it is also necessary to pay attention to the direction of the cover plate.
Fault: (2) Large switching vibration and switching shock
Reason: Switching shock occurs when the oil port pressure changes sharply during switching. At this time, the general valve core switching speed is too fast.
Solution: In order to slow down the pressure change, it is necessary to try to slow down the valve core switching speed. A small adjustable one-way throttle valve can be connected in series in the control oil circuit at both ends of the valve: or the shoulder of the reversing valve core can be designed or processed into a conical surface or a triangular throttling groove can be opened. Most of the impact problems can be solved.