Working pressure type Hydraulic system As one of the basic parameters, whether the working pressure is normal or not will greatly affect the working performance of the hydraulic system. The abnormal pressure of the hydraulic system is often manifested in the failure of the pressure regulating valve, the failure of the system pressure to establish, the complete absence of pressure, the continuous maintenance of high pressure, the pressure rising and falling down, and the instability of the pressure.

Once the pressure is abnormal, it will be difficult for the actuating elements of the hydraulic system to execute the normal working cycle. It may occur that they will not work at the original position all the time, the action speed will be significantly reduced, and the relevant control valve group will often emit harsh noise during the action, which will cause the machine to be in an abnormal state, affecting the service performance of the whole machine.

Oil cylinder manufacturer Causes of abnormal pressure

1、 Hydraulic pump Hydraulic motor Reasons for

1. The hydraulic pump and motor have been used for a long time, the internal wear is serious, the leakage is large, and the volumetric efficiency is low, resulting in insufficient output flow of the hydraulic pump and low system pressure.

2. The engine speed is too low and the efficiency is insufficient, resulting in insufficient system flow and low hydraulic system pressure.

3. The directional control device of the hydraulic pump is in the wrong position or assembled incorrectly, the pump does not work, and the system has no pressure.

II Hydraulic control valve Reason for

1. In the process of work, if the pressure is found to be stuck up and down, it is likely that the reversing valve is out of order, resulting in continuous unloading or high pressure of the system.

2. Blockage of the damping hole of the overflow valve, burr on the main valve core, dirt between the valve core and the valve hole and clearance, etc. may cause the main valve core to be stuck in the fully open position. The hydraulic oil output by the hydraulic pump directly returns to the oil tank through the overflow valve, and the pressure oil circuit is shorted to the return oil circuit, resulting in no pressure in the system; If the main valve core is stuck in the closed position by the above burr or dirt, the system pressure may continue to be too high to drop; When the valve core of the overflow valve or the reversing valve is stuck, the valve core is not flexible, and the executive parts may act sometimes but not sometimes. When the system pressure is detected, the pressure is unstable.

3. For the system with one-way valve, if the one-way valve is installed in the opposite direction, the system pressure may not rise.

4. Internal and external leakage of the system, such as serious leakage between the valve core and the valve body hole, will also cause the system pressure not to rise.

3、 Other reasons

1. Too low oil level in the hydraulic oil tank, too thin oil suction pipe, and blocked oil suction filter by impurities and dirt will lead to too large oil suction resistance of the hydraulic pump (when the hydraulic pump is empty, there is often a harsh noise), resulting in insufficient system flow and low pressure.

2. In addition, when the oil return pipe is on the liquid level (foam is generated when the oil return pipe impacts the oil in the oil tank, causing a large amount of oil in the oil tank to mix with air), the poor sealing of the oil suction pipe and air leakage will easily cause air to be mixed in the hydraulic system, resulting in unstable system pressure.