A cylindrical metal part that guides the piston to move in a straight line in a cylinder. The working fluid transforms heat energy into mechanical energy through expansion in the engine cylinder; the gas is compressed by the piston in the compressor cylinder to increase the pressure. The shell of a turbine, rotary piston engine, etc. is often called a "cylinder".

At present, there are four types of cylinders widely used today:

1、 Single acting cylinder

Only one cavity can input compressed air to realize one direction movement. The piston rod can only be pushed back by external force, usually with the help of spring force, diaphragm tension, gravity, etc.

The characteristics of single acting cylinder are as follows:

1) The structure is simple and the gas consumption is small.

2) With the spring force or diaphragm force reset, part of the compressed air energy is used to overcome the spring force or diaphragm tension, thus reducing the transmission force of the piston rod.

3) When spring and diaphragm are installed in the cylinder, the stroke is generally short; compared with the double acting cylinder of the same volume, the effective stroke is smaller.

4) The tension of the cylinder return spring and diaphragm changes with the deformation, so the output force of the piston rod changes in the process of travel.

Due to the above characteristics, single acting piston cylinder is mostly used for short stroke. Its thrust and movement speed are not required high occasions, such as air lifting, positioning and clamping devices. It can be used in long stroke and high load.