In the hydraulic transmission system, the hydraulic valve that controls the oil pressure is called the pressure control valve, which is called the pressure valve for short. The common point of this kind of valve is to use the principle that the hydraulic pressure acting on the valve core is balanced with the spring force.
In the specific hydraulic system, the requirements for pressure control are different according to the work needs: some need to limit the maximum pressure of the hydraulic system, such as safety valve; Some need to stabilize the pressure value (or pressure difference, pressure ratio, etc.) somewhere in the hydraulic system, such as overflow valves, relief valves and pressure reducing valves; Others use hydraulic pressure as a signal to control its action, such as sequence valve, pressure relay, etc.
