A linchpin, also spelled linch pin, lynchpin, or lynch pin, is a fastener used to prevent a wheel or other part from sliding off the axle upon which it is riding. The word is first attested in the late fourteenth century and derives from Middle English elements meaning "axletree pin".[1][2]

Wagon wheel, with forged linchpin
A modern linchpin with an integral spring retainer

Securing implements onto the three-point hitch of a tractor is an example of application. Linchpins may also be used in place of an R-clip for securing hitch pins.[3]

Metaphorical use


The word "linchpin" is also used figuratively to mean "something [or someone] that holds the various elements of a complicated structure together".[4]

See also

  • Circle cotter – Ring type of retaining component
  • Circlip – Type of fastener or retaining ring
  • Clevis fastener – Fastener consisting of a U-shaped bracket through which a pin is placed
  • Cotter (pin) – Pin or wedge passing through a hole to fix parts tightly together
  • Hairpin clip – reusable type of formed wire used on a grooved shaft, designed to be easily installed and uninstalled
  • Kingpin (automotive part) – Main pivot in a vehicle's steering mechanism, or part of the fifth wheel coupling for a semi truck
  • R-clip – Type of fastener made of a springy material
  • Split pin – Metal fastener with two tines that are bent during installation
  • Spring pin – Mechanical fastener that secures the position of two or more parts relative to each other


  1. ^ "linch-pin, n.". OED Online. June 2014. Oxford University Press. (accessed August 25, 2014; now behind paywall).
  2. ^ "linchpin (n.)". Online Etymology Dictionary. (accessed 1 June 2018).
  3. ^ "Hitch Pins and Linch Pins Information on GlobalSpec". Archived from the original on 2010-08-18.
  4. ^ "Linchpin". Retrieved 2012-03-24.