Hydraulic fluid exerts pressure on which component?

• A. Cylinder wall
• B. Piston
• C. Reservoir
• D. Filter

Answer: (B)

In hydraulics, the fluid’s pressure is used to push on the surface that converts energy into motion—the piston inside the cylinder. The fluid pushes against the piston face, creating a force equal to pressure times the piston area, which moves the piston and does work on the connected load. The cylinder wall mainly confines and guides the piston, not drive the work by itself. The reservoir simply stores fluid, and the filter cleans it; neither is the active work surface.