Single-acting vs double-acting cylinders: which statement best describes actuation?

Single-acting vs double-acting cylinders: which statement best describes actuation?

• A. Single-acting uses pressure on one side with an external force or spring for return; double-acting uses pressure on both sides for extend and retract.
• B. Single-acting uses pressure on both sides.
• C. Double-acting uses only mechanical spring for return.
• D. Both require return springs.

Answer: (A)

Actuation describes how a cylinder moves and is extended or retracted. A single-acting cylinder uses fluid pressure to move in one direction, and relies on a mechanical force—usually a spring or gravity—to return it to the starting position. A double-acting cylinder uses fluid pressure on both sides of the piston, so it can extend and retract by applying pressure to the appropriate side; a return mechanism isn’t required, because the opposite pressure drives the motion in the other direction. This makes the described statement the best fit: pressure on one side with a return force for the single-acting cylinder, and pressure on both sides to extend and retract for the double-acting cylinder. The other ideas don’t fit because single-acting cylinders don’t use pressure on both sides, and double-acting cylinders don’t require a return spring to function (though springs can be used in some special cases, it’s not the defining feature).

Actuation describes how a cylinder moves and is extended or retracted. A single-acting cylinder uses fluid pressure to move in one direction, and relies on a mechanical force—usually a spring or gravity—to return it to the starting position. A double-acting cylinder uses fluid pressure on both sides of the piston, so it can extend and retract by applying pressure to the appropriate side; a return mechanism isn’t required, because the opposite pressure drives the motion in the other direction.

This makes the described statement the best fit: pressure on one side with a return force for the single-acting cylinder, and pressure on both sides to extend and retract for the double-acting cylinder. The other ideas don’t fit because single-acting cylinders don’t use pressure on both sides, and double-acting cylinders don’t require a return spring to function (though springs can be used in some special cases, it’s not the defining feature).