Which system uses compressed gas to perform work?

• A. Hydraulic
• B. Solar
• C. Mechanical
• D. Pneumatic

Answer: (D)

Compressed gas powering actuators is what defines a pneumatic system. In these systems, air (or another gas) is stored under pressure and released through valves to push pistons or diaphragms in cylinders. That expansion converts pressure energy into motion, allowing quick, lightweight actuation to do work like lifting, pushing, or positioning components. The appeal is simplicity, fast response, and clean operation, but the trade-off is that the gas is compressible, so the same size actuator tends to produce less force and finer control can be trickier than with liquids. Hydraulic systems, by contrast, use incompressible fluid for higher forces; mechanical systems rely on rigid moving parts; solar refers to energy from sunlight rather than a gas-driven mechanism.