This document specifies dimensions of ball-bearing turntable when mounted on a vehicle which is part of vehicle combinations specified in of ISO 18868:2013, Clause 4, to ensure their interchangeability. This document also applies to the following: — drawbar trailers using a ball-bearing turntable to steer the front axle; — ball-bearing turntables assembled with the fifth-wheel of the road tractor (truck) to improve steering manoeuvre.