A linchpin, also spelled lynchpin, is a

fastener A fastener (US English) or fastening (UK English) is a hardware device that mechanically joins or affixes two or more objects together. In general, fasteners are used to create non-permanent joints; that is, joints that can be removed or disman ...

used to prevent a

wheel A wheel is a rotating component (typically circular in shape) that is intended to turn on an axle Bearing (mechanical), bearing. The wheel is one of the key components of the wheel and axle which is one of the Simple machine, six simple machin ...

or other part from sliding off the

axle An axle or axletree is a central shaft for a rotation, rotating wheel and axle, wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In ...

upon which it is riding. The word is first attested in the late fourteenth century and derives from

Middle English Middle English (abbreviated to ME) is a form of the English language that was spoken after the Norman Conquest of 1066, until the late 15th century. The English language underwent distinct variations and developments following the Old English pe ...

elements meaning "axletree pin". Securing implements onto the

three-point hitch The three-point hitch (British English: three-point linkage) is a widely used type of hitch for attaching ploughs and other farm equipment, implements to an agricultural or industrial tractor. The three points resemble either a triangle, or the le ...

of a

tractor A tractor is an engineering vehicle specifically designed to deliver a high tractive effort (or torque) at slow speeds, for the purposes of hauling a Trailer (vehicle), trailer or machinery such as that used in agriculture, mining or constructio ...

is an example of application. Linchpins may also be used in place of an

R-clip __NOTOC__ An R-clip, also known as an R-pin, R-key, hairpin cotter pin, hairpin cotter,. bridge pin, hitch pin clip or spring cotter pin, is a fastener made of a durable but flexible material, commonly hardened metal wire, resembling the shape of ...

for securing hitch pins.

Metaphorical use

The word "linchpin" is also used figuratively to mean "something r someonethat holds the various elements of a complicated structure together".

References

Fasteners Horse-drawn vehicle parts 14th-century neologisms {{tech-stub

Metaphorical use

See also

References