Limiting the maximum pressure by pressure relief valves
For safety and component protection, it is necessary for almost any hydraulic system to limit the pressure of the system. For low flow rates you can use directly controlled pressure relief valves.
The shutter element is pressed onto the seat in accordance with the strenth of the spring and preset (usually adjustable). Exceeds the pressure of the oil the spring force - which means high pressure, the cone opens the connection so that the oil flows back directly in the tank.
How the pressure relief valve is switched within the hydraulic circuit to act as an safety device is shown in the following illustration below:
It is not in the main stream, but connected in the secondary flow.
- The initial position is closed
- The valve is connected in parallel to the pump