Pneumatic systems are used to compress air to produce mechanical motion. An example of a pneumatic system is the compression brakes on large trucks and city buses. This pneumatic system works when a friction break compresses air and pressure is applied to a piston. The piston then applies the pressure to a brake pad, which stops the vehicle.
Pneumatic systems can be divided into two general categories: systems that are powered by a rotating rotor and systems that are powered by a reciprocating piston. Devices powered by a rotating rotor contain a housing compartment, vanes and a central spindle. Air enters the housing and applies pressure to the vanes, which causes the spindle to rotate. Then, the mechanism that is attached to the spindle begins to move. Examples of devices with rotating rotor systems include rock drills, grinders and buffers.
On the other hand, a reciprocating piston pneumatic system is powered by compressed air entering a cylinder and expanding until a piston moves. This type of system is usually used to power motors. However, smaller tools, such as a riveting hammer, are powered by reciprocating pistons.
Essentially, pneumatic systems work by compressing air to a higher pressure. The high pressure then forces a spindle or piston to move, which powers a tool or motor.