Hydraulic components - Check valve

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Check valves are the simplest form of hydraulic devices in that they permit free oil flow in one direction and block oil flow in the opposite direction. Check valves may also be used as a directional or pressure control in a hydraulic system. Oil is flowing in from the left side port, through the check valve and out the right side port. If the pressure equalizes or is higher in the right side port, the check valve will close and block flow in the opposite direction. The spring rating varies based on how the valve is used in the system. One of the most common locations for a check valve is immediately downstream of the hydraulic pump. When used in this application, the spring pressure rating is usually 1-5 pounds per square inch (psi) and therefore not shown with the symbol. In this case, the valve is used as a directional control in that it allows oil flow from the pump to the system but blocks flow in the reverse direction. This is commonly called a pump isolation check valve.

This valve serves four functions within the system:

Block Pressure Spikes Prevent Oil Lines from Draining Block Oil Flow from the Accumulator Prevent Oil Flow from the Online Pump to the Offline Pump

Type of check valves:

Ball Piston, Stop check valves

Piston check valve Piston check valve Ball check valve Ball check valve