Which statement explains why the rod side of a cylinder affects retraction speed?

• A. The rod side has a smaller cross-sectional area, increasing velocity on retraction
• B. The rod side has a larger cross-sectional area, increasing velocity on retraction
• C. The rod side area has no impact on speed
• D. The rod side reduces friction to speed up extension

Answer: (A)

What’s being tested is how the fluid volume and piston area interact to set speed. In a hydraulic cylinder, the piston moves in response to a flow rate Q, and its speed is essentially Q divided by the effective area it has to push against. On the rod side, the rod itself occupies part of the piston face, so the effective area there is smaller than on the bore side. During retraction, fluid into the rod side has to move the piston across that smaller area. With the same flow rate, a smaller area means the piston must travel farther per unit time, so the retraction speed increases. If the rod-side area were larger, the piston would move more slowly for the same flow. The speed is fundamentally tied to how much area the fluid must move against, not to friction alone, so a reduced rod-side area naturally leads to faster retraction.