Pneumatic Air Cylinders Explained
A pneumatic cylinder is a type of air cylinder that uses pneumatic air pressure to operate the cylinder. Pneumatic cylinders vary between miniature air cylinders and larger air cylinders, depending on the application. There are two main types of pneumatic miniature air cylinders, the single acting cylinder and the double acting cylinder. In general, the cylinders are used for door opening and closing mechanisms, hoists and jacks, gates, actuator valves, and in certain industrial machines.
Pneumatic air cylinders can be either passive or active. Active cylinders require a power source to activate the device and provide pressure. Passive cylinders act on their own without a power source. Usually, active cylinders are used in machinery and hoists, while passive cylinders are often used for door-controlling mechanisms. While both single and double acting cylinders have similar properties, they are different enough to make the choice important for most uses.
Single acting: Single acting pneumatic cylinders apply air pressure to one side of the cylinder only. The air pressure causes the pistons inside the cylinder to retract or expand. This makes the cylinder work for only one direction of movement. To compress the cylinder again, the unit uses springs or the weight of an object pressing on the cylinder to return it to the original position. Car hoists and damper valves are two examples of single acting pneumatic cylinders.
Double acting: Double acting cylinders apply pneumatic force on either side of the pistons inside the cylinder. This enables the cylinder to work in two directions of movement. These air cylinders are often used in reciprocating devices, such as saws, pumps, presses, and part insert and removal mechanisms. Double acting cylinders are used more often in industrial settings, because they do not require springs or any other mechanisms to retract and expand.