A primary function of the 3-way valve is to save/store air that's compressed in high cyclic applications.
4-way valves are used for systems that require higher air pressure.
[3] Four-way valves are the most commonly used components for directional control in a pneumatic system.
Their most common function is to regulate the motion of a cylinder, motor, or other powering components.
Pneumatic systems support production lines, mechanical clamps, train doors, and many other parts of industrial businesses.