Pneumatic cylinders take air pressure that is delivered by an air circuit and convert it into applied force and straight-line motion. They can be very small, such as the one you see on a screen door. Or, they can be extremely large and heavy-duty, such as one which produces several tons of force for use in a steel mill. They have the same basic design as a hydraulic cylinder. However, while a hydraulic cylinder can be designed to work under several operating pressures, pneumatic cylinders must be designed with bigger cross-sectional areas if larger forces are to be used.
Pneumatic cylinders are used in numerous applications. One example is the air cylinder for a bottom (belly) dump trailer that we manufacture (see home page). Because pneumatic cylinders are so versatile in the types of forces and motion they can produce, they are very popular.
In general, pneumatic cylinders are classified in three categories: light duty, medium duty and heavy duty. They can be designed as single-acting where the air pressure forces the piston to move in one direction only and the piston is returned by gravity or an external spring. Or, they can be designed as double-acting where the air pressure moves the piston in both directions.