In a 3000 psi hydraulic system, a double-acting cylinder has a piston area of 3 square inches on the extension side and a rod attached with a cross sectional area of 1 square inch on the rod side. When retracting, what is the force produced?

• A. 6000 pounds
• B. 3000 pounds
• C. 12000 pounds
• D. 9000 pounds

Answer: (A)

Retracting force in a double-acting hydraulic cylinder depends on pressure times the effective area on the rod side, because the rod occupies part of the bore and reduces the area available to push. With a piston area of 3 in² and a rod area of 1 in², the effective retracting area is 3 − 1 = 2 in². At 3000 psi, the force produced while retracting is 3000 × 2 = 6000 pounds. For context, extending would push with 3000 × 3 = 9000 pounds, since the full piston area is used.