Which statement correctly describes pneumatic and hydraulic cylinders?

Which statement correctly describes pneumatic and hydraulic cylinders?

• A. Hydraulic uses compressed air and is typically faster with lower force.
• B. Pneumatic uses compressed air and is typically faster with lower force.
• C. Pneumatic uses incompressible fluid and provides higher force.
• D. Hydraulic uses liquids and is faster than pneumatic.

Answer: (B)

The main idea here is how the working fluid determines speed and force in cylinders. Pneumatic cylinders use compressed air, which is a compressible gas. That compressibility lets the piston move quickly when air is admitted or vented, giving fast actuation, but the energy stored per unit volume is relatively low, so the force produced is typically smaller. Hydraulic cylinders use a nearly incompressible liquid, so high pressure can be turned into large forces on the piston, delivering much greater force. The trade-off is that moving that hydraulic fluid through the system tends to be slower and more controlled, especially under load. So the statement that pneumatic uses compressed air and is typically faster with lower force aligns with the common characteristics of these two types of actuators.

The main idea here is how the working fluid determines speed and force in cylinders. Pneumatic cylinders use compressed air, which is a compressible gas. That compressibility lets the piston move quickly when air is admitted or vented, giving fast actuation, but the energy stored per unit volume is relatively low, so the force produced is typically smaller. Hydraulic cylinders use a nearly incompressible liquid, so high pressure can be turned into large forces on the piston, delivering much greater force. The trade-off is that moving that hydraulic fluid through the system tends to be slower and more controlled, especially under load. So the statement that pneumatic uses compressed air and is typically faster with lower force aligns with the common characteristics of these two types of actuators.