A bolt coupling device comprises a drawbar, a swivelable cast "bell" with a horizontal opening in the middle, a machined pin or "bolt", an automatic pin release mechanism, a safety locking device with actuating handle and a cushioned mounting plate.

The vehicle is reversed slowly until the drawbar eye enters the bell, tripping the bolt and closing the coupling.

A check is made of the coupling to ensure full engagement, air lines and electrics hooked up and drawbar leg stowed.

Ringfeders are used in nearly all aspects of world transport, the most common being large goods vehicles throughout Europe, and road trains in Australia.

It is a must for a ballast tractor due to lack of a fifth wheel, making drawbar coupling the only option to connect hydraulic modular trailers (HMTs).