Crank

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A crank is a mechanical component used to convert rotational motion into reciprocating motion, or vice versa. It consists of an arm attached at a right angle to a rotating shaft by which it is driven or does the driving. Cranks are commonly used in a wide range of applications, including engines, pumps, and other machinery.

Design and Function

The basic design of a crank consists of the arm, the shaft (or axle), and the crank pin or bearing. The crank pin connects the crank to the connecting rod, which in turn is connected to a piston or other reciprocating part. As the shaft rotates, the crank converts the rotational motion of the shaft into the up-and-down motion of the piston.

Types of Cranks

There are several types of cranks, including:

• Simple crank: Used in single-cylinder engines.
• Crankshaft: A series of cranks linked together, used in multi-cylinder engines.
• Hand crank: Manually operated by hand to perform tasks such as starting an engine or operating a mechanical device like a coffee grinder.

Applications

Crank mechanisms are essential in many mechanical systems. Some common applications include:

• Internal combustion engines
• Steam engines
• Pumps
• Bicycles (via the pedal crankset)
• Music boxes

History

The concept of the crank dates back to ancient times, with evidence of its use in Roman Egypt for ballistae. The technology was further developed during the Industrial Revolution when it became crucial for operating industrial machinery.

See Also

• Camshaft
• Flywheel
• Piston
• Crankshaft position sensor