It was thought that evidence of the earliest true crank handle was found in a Han era glazed-earthenware tomb model of an agricultural winnowing fan dated no later than 200 AD, but since then a series of similar pottery models with crank operated winnowing fans were unearthed, with one of them dating back to the Western Han dynasty (202 BC - 9 AD). The upright handle of such rotary handmills, set at a distance from the centre of rotation, works as a crank. See also: Science and technology of the Han dynasty Tibetan operating a quern (1938). There is usually a bar perpendicular to the other end of the arm, often with a freely rotatable handle or pedal attached.Ī compound crank Examples Hand crank on a pencil sharpener Animation of a multi-cylinder engine In this case a person's arm or leg serves as the connecting rod, applying reciprocating force to the crank. The term often refers to a human-powered crank which is used to manually turn an axle, as in a bicycle crankset or a brace and bit drill. Attached to the end of the crank by a pivot is a rod, usually called a connecting rod (conrod). The arm may be a bent portion of the shaft, or a separate arm or disk attached to it. When combined with a connecting rod, it can be used to convert circular motion into reciprocating motion, or vice versa. Simple machine transferring motion to or from a rotating shaft at a distance from the centreline Hand crank for a winch on a sailboat - commonly referred to as a winch handle.Ī crank is an arm attached at a right angle to a rotating shaft by which circular motion is imparted to or received from the shaft.
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