A hit-and-miss engine is a type of flywheel engine. A flywheel engine is an engine that has a large flywheel or set of flywheels connected to the crankshaft. The flywheels maintain engine speed during engine cycles that do not produce driving mechanical forces. The flywheels store energy on the combustion stroke and supply the stored energy to the mechanical load on the other three strokes of the piston. When these engines were designed, technology was less advanced and manufacturers made all parts very large. A typical engine weighs approximately 1000 pounds (454 kg). Typically, the material for all significant engine parts was cast iron. Small functional pieces were made of steel and machined to tolerance.