What is the basic principle by which a hydraulic actuator produces motion?

What is the basic principle by which a hydraulic actuator produces motion?

• A. Pressure acting on the piston creates a force that moves the piston rod, producing linear motion.
• B. The fluid compresses and expands to rotate a shaft.
• C. Electrical energy is converted to a magnetic field to move the rod.
• D. Pneumatic air cushions push a rack to rotate the output.

Answer: (A)

The basic idea is that pressurized hydraulic fluid pushes on the piston surface inside a cylinder, generating a force F = P × A that moves the piston rod in a straight line. The fluid’s confinement and near-incompressibility let that pressure be transmitted efficiently to the piston, producing controlled, high-force linear motion—the core function of a hydraulic actuator. The other descriptions mix in rotations or different energy forms: rotating motion isn’t produced merely by fluid compression in a standard hydraulic actuator, electrical-to-magnetic conversion describes an electric motor, and a pneumatic arrangement uses air instead of liquid.

The basic idea is that pressurized hydraulic fluid pushes on the piston surface inside a cylinder, generating a force F = P × A that moves the piston rod in a straight line. The fluid’s confinement and near-incompressibility let that pressure be transmitted efficiently to the piston, producing controlled, high-force linear motion—the core function of a hydraulic actuator.

The other descriptions mix in rotations or different energy forms: rotating motion isn’t produced merely by fluid compression in a standard hydraulic actuator, electrical-to-magnetic conversion describes an electric motor, and a pneumatic arrangement uses air instead of liquid.