In a hydraulic cylinder, if the piston area is 1.2 square inches and the fluid pressure is 850 psi, what is the force exerted on the piston?

• A. 1020 pounds
• B. 850 pounds
• C. 1.2 pounds
• D. 102 pounds

Answer: (A)

In hydraulics, the force on a piston comes from multiplying the fluid pressure by the piston’s area. Multiply 850 psi by the piston area of 1.2 square inches: 850 × 1.2 = 1020 pounds. The units work out because psi (pounds per square inch) times square inches gives pounds of force.

This shows why a hydraulic cylinder can generate large forces with comparatively high pressure if the piston area is sizable. If the area were smaller or larger, the force would scale accordingly: exactly 850 pounds would occur with a 1 square inch area, and other numbers reflect different areas.