The crankshaft is a shaft having one or more cranks, especially the main shaft, of an internal-combustion engine to which the connecting rods are attached. It is part of the engine that translates reciprocating linear piston motion into rotation. In order to do that, the crankshaft has “crankthrows” or “crankpins”, which are additional bearing surfaces whose axis is offset from that crank, to which the big ends of the connecting rods from each cylinder attach. The earliest evidence for a crank and connecting rod in a machine appeared in the late Roman Heirapolis sawmill from the 3rd century AD and two Roman stone sawmills at Gerasa, Roman Syria, and Ephesus, Asia Minor (both 6th century AD). Crankshafts can be forged from a steel bar usually through roll forging or cast in ductile steel. In today’s time, manufacturers favor using forged crankshafts due to the lighter weight, compact dimensions, and better inherent dampening. With forged crankshafts, vanadium micro-alloyed steels are mostly used as they can be air cooled after reaching high strengths without additional heat treatment. The low alloy content also makes the material cheaper than high alloy steels. Carbon steels are also used, but they require additional heat treatment to reach desired properties. Iron crankshafts now a days are mostly found in cheaper production engines, such as Ford Focus diesel engines, where loads are lower. Some engines also use cast iron crankshafts for low output versions while the more expensive high output versions use forged steel.