Crankpin

A crankpin or crank journal is a journal in an engine or mechanical device. That is, the part of a shaft or axle that rests on bearings. A crankpin or crank journal is a journal in an engine or mechanical device. That is, the part of a shaft or axle that rests on bearings. In a reciprocating engine, the crankpin is the part of a crankshaft where the lower end of a connecting rod attaches. In a beam engine, a single crankpin is mounted on the flywheel; In a steam locomotive, crankpins are often mounted directly on the driving wheels. A crankpin is separated from its shaft or axle by a bearing. These are commonly bushings or plain bearings, but less commonly may be roller bearings. In a multi-cylinder engine, a crankpin can serve one or many cylinders, for example: