Without engines, our world literally would not run. Since the steam engine came into play during the Industrial Revolution, we have come to depend on engines to get us where we need to go, keep us comfortable in our homes, and just keep our lives on track. From the internal combustion engines used in vehicles to the niche application Stirling engine, we simply need this technology. Engines are very sophisticated, however, and cannot run without each part running smoothly. Read on to learn more about some of the smaller details that make our essential reciprocating engines run.

Reciprocating Engines
Reciprocating engines, also known as piston engines, are often categorized by whether they are single or double acting, depending on how the fluid acts on the piston. These pistons are used to convert pressure into a rotating motion, which makes the engine run.

Single Acting Cylinder
In reciprocating engines, a single acting cylinder is a cylinder where the working fluid acts on only one side of the piston. It relies on the load, other cylinders, springs, and the momentum of a flywheel to push the piston in the opposite direction. They are often found in hydraulic rams and pumps, as well as in many external combustion engines and some steam engines.

Double Acting Cylinder
A double-acting cylinder, on the other hand, is a cylinder where the working fluid acts alternately on either side of the piston. A hole must be drilled in one end of the cylinder for the piston rod to connect the piston to an external mechanism, like a crankshaft. This hole is then fitted with a gland, also known as a stuffing box, to prevent the escaping of the working fluid. Double acting cylinders are very popular in steam engines, but relatively rare in other types.

Applications
Steam engines typically use double acting cylinders. However, very early versions often used a single acting cylinder. These older versions were typically used for pumping mineshafts. In contrast, almost all internal combustion engines use single acting cylinders. This means that this is the type of cylinder you’re likely to find in most modern cars.