In a hydraulic press, increasing the size of the output piston relative to the input piston increases what?

• A. The output force
• B. The output speed
• C. The input force
• D. The system pressure

Answer: (A)

In a hydraulic system, pressure in the fluid is shared across the circuit and forces scale with piston area. If you push on the input piston with force F_in and it has area A_in, the pressure produced is P = F_in / A_in. This same pressure acts on the output piston, which has area A_out, giving an output force F_out = P × A_out = F_in × (A_out / A_in). So, increasing the output piston area relative to the input increases the output force because the same pressure pushes on a larger area, producing a larger force.

At the same time, the speed of the output piston changes with the areas due to volume conservation: A_in × v_in = A_out × v_out, which means v_out = v_in × (A_in / A_out). A larger output area reduces the output speed for the same input motion.

System pressure stays essentially the same for a given input force (ignoring losses); it would only rise if the load required more force, forcing you to increase the input force. Therefore, the most direct effect of enlarging the output piston is an increase in output force.