Excavator loader main gun relief valve 723-40-94501

Most excavators have two main pumps, so the main relief valve has two (also known as the main safety valve), respectively control the respective main pump, and then each main pump controls 3 actions, the bucket and the big arm walk with one side is a group, the middle arm, the rotation and the exception of the side walk is a group, all two main relief valves (pilot relief valves) control the opposite three actions.

And finally they also have their own relief valves for each action, such as the lifting arm and the lowering arm which have their own relief valves. The main relief valve mainly regulates the pressure of the two main pumps, so the pressure of the three actions controlled by the main pump is the same, according to the requirements, if the pressure of a single action is not enough or too high, then the separate relief valve of the action can be adjusted.

On the main valve, there is a clear difference from other relief valves. The main relief valve of the excavator with the function of strengthening will have more than one pilot pipe. The problem of the main relief valve is generally that the internal spring is broken or failed, the valve core is worn, and the whole operation is weak and the pressure cannot be established.

After a PC200-6 fully hydraulic excavator is started, the working device can realize various actions, but the main pump sends out abnormal noise.

According to the preliminary analysis, it is believed that the pump is vacuumed or the oil circuit is mixed with air. Therefore, first adjust the working device to the oil level detection position, and check that the oil level of the hydraulic tank is below the low level of the oil target, which is the position of oil shortage. After asking the driver, the sealing ring of the high-pressure oil pipe leading to the rodless chamber of the bucket rod cylinder was replaced due to oil leakage during work, but the oil level was not checked in time after replacement. Therefore, firstly, the hydraulic oil tank is refueled to the standard oil level, and the test shows that the abnormal noise is reduced, but it still exists; Then, through the main pump exhaust valve to the main pump after the re-test, it is found that the abnormal noise is still there, indicating that the noise can not be completely caused by the pump suction.