The valves enable flow direction control of fluid in a hydraulic circuit and both control of the direction of movement or (shutting off) stopping of their appliances. In addition to solenoid operated valves, valves are also operated mechanically by lever or cam, hydraulically or pneumatically.
Fluid flows through the inlet, a small pressure is needed to open the valve seat in this direction.
Two positions of the shuttle valve are shown here. When the pressure of the flow on one side.
Two-way valves are also simple two positions ON/OFF valves but actuated by actuators such as solenoid actuators.
These valves have three nodes that’s why named three-way valve and three-way valves.
Four-way valve or three position valves which got three working positions for the actuators to control the flow direction.