Function and working principle of overflow check valve in water jet cleaning machine

　　Overflow check valve keeps cleaning machine system working pressure within the set value. Used to protect high pressure water systems from overload, control pressure and relieve pressure. The control piston is kept at the end position under the action of disc spring, so that check valve and the valve stem are closed at the same time. When output pressure of pump gradually increases, check valve is opened, and the pressure of high-pressure system is equal to pump’s pressure. When high-pressure water system exceeds the set pressure value, the control piston drives the valve stem to move upward, opens the bypass, and discharges the high-pressure water output by the pump to the water tank through the bypass. At this time, the check valve is closed under the action of back pressure of discharge pipeline. Under the action of check valve, the pressure line can be separated from pump system, so the pressure of discharge line can be maintained. When pressure of discharge line drops to a normal value, the control piston returns to the initial position under the action of disc spring force, which drives the valve stem to descend, and then bypass is closed, so that water pump can generate pressure again.