EC360 Main Control Valve Relief Valve

In large-scale construction machinery like EC360, the main control valve safety valve is a crucial component in the hydraulic system. It is mainly used to limit the maximum pressure of the system and protect the entire hydraulic circuit. When the system pressure rises sharply due to sudden load changes, operational errors, or other reasons and exceeds the set safety value, the safety valve opens quickly, allowing the excess hydraulic oil to flow back to the tank, thereby preventing the system pressure from continuing to rise and avoiding damage to hydraulic components such as hydraulic pumps, cylinders, and motors due to overpressure. It also ensures the safe and stable operation of the equipment and the personal safety of the operators.

Working Principle
The safety valve typically adopts a spring-loaded structure. Under normal working conditions, when the system pressure is lower than the set pressure of the safety valve, the valve core remains closed under the force of the spring, and the hydraulic oil circulates in the system along the normal path. Once the system pressure rises and reaches or exceeds the set pressure of the safety valve, the pressure of the oil overcomes the spring force, pushing the valve core to move and opening the safety valve. The hydraulic oil then flows back to the tank through the outlet of the safety valve, and the system pressure drops. When the system pressure drops below the set pressure of the safety valve, the spring force pushes the valve core back to the closed position, stops the overflow, and the hydraulic system returns to its normal working state. This dynamic regulation mechanism can monitor and stabilize the system pressure in real time.

Common Faults and Troubleshooting
Pressure cannot be increased: It may be that the valve core inside the safety valve is stuck by impurities and remains in the open position, causing the hydraulic oil to continuously overflow back to the tank and unable to build up sufficient system pressure. At this time, the safety valve needs to be disassembled, and the valve core and valve seat should be cleaned to remove impurities. Additionally, a broken or weakened spring can also cause the safety valve to open prematurely and fail to maintain normal pressure. In this case, a new spring that meets the specifications needs to be replaced.
Excessively high pressure and the safety valve does not open: The common cause is that the valve core is stuck in the closed position due to rust, deformation, or other reasons and cannot open normally to overflow. The valve core should be inspected. If it is rusty, rust removal treatment should be carried out; if it is severely deformed, the valve core needs to be replaced. Moreover, if the spring is too hard or improperly adjusted, causing the opening pressure of the safety valve to be too high, this situation can also occur. The preload force of the spring needs to be readjusted to ensure that the opening pressure meets the design requirements of the equipment.
Large system pressure fluctuations: Faults in the pilot valve part of the safety valve, such as poor sealing of the pilot valve core, can cause unstable pilot pressure, leading to frequent opening and closing of the main safety valve and causing system pressure fluctuations. The sealing condition of the pilot valve core should be checked, and the sealing parts should be replaced or the valve core repaired. It could also be that there is air in the system, causing pressure fluctuations when the pressure changes. In this case, system air release operations should be performed.

Maintenance Points
Regular inspection: According to the equipment maintenance manual, regular visual inspections of the safety valve should be conducted to check for leaks, damage, and other conditions. At the same time, check if the connection parts are loose to ensure the safety valve is securely installed.
Cleaning: Keep the area around the safety valve clean to prevent dust and impurities from entering the safety valve. When disassembling and repairing the safety valve, thoroughly clean the valve core, valve seat, and other parts to avoid impurities affecting their normal operation.
Pressure calibration: Use professional pressure calibration equipment to calibrate the opening pressure of the safety valve at regular intervals or after major equipment overhauls to ensure it is within the specified range. If the opening pressure is inaccurate, it should be adjusted in a timely manner.