A double rod cylinder _________.

• A. Is single-acting
• B. Has a piston area twice the annular area
• C. uses the load to retact the rod
• D. extends and retracts each rod at the same speed

Answer: (D)

In a double rod cylinder the piston has a rod on each end, so hydraulic pressure acts on two faces that are reduced by the same rod cross-section. Because these two faces have equal effective areas, a given hydraulic flow makes the piston move at the same speed in either direction. As a result, each rod extends or retracts by the same amount and at the same speed when the piston shifts. The other statements don’t match how a double rod cylinder behaves: it isn’t single-acting, retract speed isn’t determined by load in this setup, and the piston area versus annular area isn’t a simple “twice” relationship since both sides are equally reduced by the rod.