Steam Engines

Where these were used for pumping mine shafts and only had to act against a load in one direction, single-acting designs remained in use for many years. The main impetus towards double-acting cylinders came when James Watt was trying to develop a rotative beam engine, that could be used to drive machinery via an output shaft. With a single-cylinder engine, a double-acting cylinder gave a smoother power output. The high-pressure engine, as developed by Richard Trevithick, used double-acting pistons and became the model for most steam engines afterwards.

Some of the later steam engines, the high-speed steam engines, used single-acting pistons of a new design. The crossheadbecame part of the piston,and there was no longer any piston rod. This was for similar reasons to the internal combustion engine, as avoiding the piston rod and its seals allowed a more effective crankcase lubrication system.

Small models and toys often use single-acting cylinders for the above reason but also to reduce manufacturing costs.