The Hydraulic three-way shuttle valve is a type of directional control valve. It is similar to a spool valve but contains raised areas, called lands, that block or open ports for valve operation.
In the normal operating position of a hydraulic three-way shuttle valve, fluid enters from the normal system inlet port and flows through the valve to the unit outlet port. Afterward, the flow is passed out from the outlet port to the actuating unit, which may be a pneumatic or hydraulic cylinder.
A ball, or other blocking valve element, is located inside the valve to seal off one or both of the inlet ports.
If the pressure to inlet port X is higher than the pressure to alternate port Y, the ball will move towards the right side and block X and Y and link them together. Similarly, if the pressure to alternate port Y is lower than X, the ball will move towards the left side and block Y and link them together.
This feature distinguishes the hydraulic three-way shuttle valve from opposed check valves mounted back to back. Opposed check valves allow flow from one of two inlet ports to a third, but they block flow from the outlet port to both inlets.
