Return connecting rod engine

A return connecting rod, return piston rod or (in marine parlance) double piston rod engine or back-acting engine is a particular layout for a steam engine.

The key attribute of this layout is that the piston rod emerges from the cylinder to the crosshead, but the connecting rod then reverses direction and goes backwards to the crankshaft. This layout is compact, but has mechanical disadvantages. Return connecting rod engines were thus rarely used.