The differences in operation between a single-acting cylinder and a double-acting cylinder in pneumatic control. - Leaving Cert Engineering - Question i - 2014

A single-acting cylinder is a pneumatic device that utilizes compressed air to move the piston in one direction. Once the air is released, the piston will return to its original position, typically due to a spring mechanism or gravity. This operation means single-acting cylinders only require air pressure to extend the piston, while the return action is passive.

In contrast, a double-acting cylinder requires compressed air for both the extension and retraction of the piston. While it needs air pressure to move the piston in either direction, it can hold its position even when the air supply is turned off, as the air pressure maintains position. To return the piston to its original position, it again needs compressed air to push the piston back.

In summary:

• Single-acting cylinders: Air moves piston in one direction; passive return.
• Double-acting cylinders: Air moves piston in both directions; requires air for both actions.