FAA Aviation Mechanic Airframe (AMA)Hydraulic and Pneumatic SystemsMedium
A hydraulic actuating cylinder is designed so that fluid pressure can be applied to either side of the piston to move it in both directions, with mechanical force from the fluid used for both extension and retraction. What type of actuator is this?
- ASpring-loaded actuator
- BSingle-acting actuator
- CDouble-acting actuator
- DRotary actuator
Show answer & explanationAnswer & explanation
Correct answer: C. Double-acting actuator
A double-acting actuator has fluid ports on both sides of the piston, allowing hydraulic pressure to move the piston in either direction. A single-acting actuator uses fluid pressure for movement in only one direction, relying on a spring or other force (such as gear weight) to return it.
Why the other options are wrong
- A. Spring-loaded actuators use a spring, not fluid, for the return stroke.
- B. Single-acting actuators only use fluid pressure in one direction.
- D. Rotary actuators produce rotational, not linear, motion.
Double-Acting Actuator
A hydraulic actuator with ports on both sides of the piston, allowing fluid pressure to extend and retract the piston.
- Contrasts with single-acting actuators (fluid one direction only)
- Common in landing gear, flight control actuators
- Requires selector valve to direct fluid to each side
Memory trick: Double-acting pushes both ways, like a two-way door.