What is the difference between a "double-acting" and a "single-acting" cylinder?

A double-acting cylinder utilizes air pressure to produce motion in both the extending and retracting strokes of the piston. This design allows for greater efficiency and control in applications that require bidirectional movement. Air is applied to one side of the piston to extend it, and then pressure can be applied to the opposite side to retract it, enabling powerful movements without returning springs or other complicating mechanisms. This dual functionality is a significant advantage in pneumatic systems, as it improves productivity and versatility in operations.

The other options do not accurately reflect the characteristics of these cylinder types. Single-acting cylinders can operate at different pressures, but they are designed primarily to exert force only in one direction and often rely on a spring or external force for the return stroke. The mention of hydraulic fluids versus air does not pertain to the distinction between single and double-acting cylinders, as both types can be utilized in pneumatic or hydraulic applications. Weight varies based on design and size rather than cylinder type alone.