US Patent 7762167 Methods of modifying a trailer kingpin in situ

A method of enlarging a kingpin which attaches a trailer to a fifth wheel on a tractor includes the step of providing a collar having a base, shank and head with the shank having a desired diameter. The collar also has an internal aperture having a first portion of a certain diameter and a second portion of lesser diameter. An existing kingpin is machined in situ on the trailer to a dimension commensurate with the internal apertures of the collar. The collar and machined kingpin are then joined to form a new kingpin having the desired diameter.