A cotter is a pin or
wedge
A wedge is a triangle, triangular shaped tool, a portable inclined plane, and one of the six simple machines. It can be used to separate two objects or portions of an object, lift up an object, or hold an object in place. It functions by conver ...
with a flat bearing surface passing through a hole to fix parts tightly together. In British usage cotter pin has the same meaning,
[.] but in the U.S. it means a
split pin
A split pin, also known as a cotter pin, or cotter key in the United States of America, US, is a metal fastener with two wiktionary:tine, tines that are bent during installation, similar to a staple (fastener), staple or rivet. Typically made o ...
.
Typical applications are in fixing a
crank
Crank may refer to:
Mechanisms
* Crank (mechanism), in mechanical engineering, a bent portion of an axle or shaft, or an arm keyed at right angles to the end of a shaft, by which motion is imparted to or received from it
* Crankset, the componen ...
to its
crankshaft
A crankshaft is a mechanical component used in a reciprocating engine, piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating Shaft (mechanical engineering), shaft containing one or more crankpins, ...
, as in a bicycle, and a
piston rod
In a piston engine, a piston rod joins a piston to the crosshead and thus to the connecting rod that drives the crankshaft or (for steam locomotives) the driving wheels.
Internal combustion engines, and in particular all current automobile engin ...
to a
crosshead
In mechanical engineering, a crosshead is a mechanical joint used as part of the slider-crank linkages of long stroke reciprocating engines (either internal combustion or steam) and reciprocating compressors to eliminate sideways force on the ...
, as in a steam engine. The angle of the wedge determines the position of the parts being held; therefore, on a bicycle, the pedal arms will only be at 180 degrees to each other if the angle of the cotter pin's wedge is the same on both pins.
Popular usage
Formerly, it was common to mount
bicycle
A bicycle, also called a pedal cycle, bike, push-bike or cycle, is a human-powered transport, human-powered or motorized bicycle, motor-assisted, bicycle pedal, pedal-driven, single-track vehicle, with two bicycle wheel, wheels attached to a ...
cranks using a cotter, although now a more easily maintained arrangement is typically used, such as a square tapered or splined interface. These cotters have a short
threaded section at the narrower end of the taper, which is used to hold the cotter in place with a
washer and
nut
Nut often refers to:
* Nut (fruit), fruit composed of a hard shell and a seed
* Nut (food), a dry and edible fruit or seed, including but not limited to true nuts
* Nut (hardware), fastener used with a bolt
Nut, NUT or Nuts may also refer to:
A ...
. They are also used to secure
ceiling fans to prevent falling if the mounting nut loosens.
See also
*
*
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*
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References
External links
*{{Commons category-inline, Split cotter pins
Cottered Cranks by Sheldon Brown
Bicycle parts
Fasteners