Kingpin (automotive part)

Similar centre pivot steering was used by steam traction engines, the kingpin being mounted on the 'perch bracket' beneath the boiler.

Although they are largely obsolete, kingpin suspensions have the advantage of being able to carry much heavier weights,[dubious – discuss] which is why they are still featured on some heavy trucks.

The nipple at the front of a semi-trailer to connect to a fifth wheel coupling on a tractor unit is also known as a kingpin, which usage is analogous to the original horse-drawn wagon and traction engine steering use.

On most modern designs, the kingpin angle is set relative to the vertical, as viewed from the front or back of the vehicle, and it is not adjustable, changing only if the wheel spindle or steering knuckles are bent.

With ruthless logic Ford concluded that the kingpins on the Model T were too good for their job and ordered that in future they should be made to an inferior specification.

The metaphor has been cited by several prominent science writers including Richard Dawkins,[4] John Barrow,[5] and Jared Diamond.

[6] Biologists Robert A. Laird and Thomas N. Sherratt have questioned both the truth of the story and the utility of the metaphor, pointing out that evolution of multicomponent systems need not result in identical component failure rates.