attelage haut

CONT: ... the coupling process … There is a horseshoe-shaped structure at the back of tractor or towing portion of the tractor-trailer rig known as the ""fifth wheel"" that the driver must carefully line up on a flat surface with a ""king pin"" … Once properly coupled, the surface of the semi-trailer (with the kingpin at the centre) rotates against surface of the fixed fifth wheel, which does not rotate. One of the mistakes that can occur when the towing vehicle is not properly lined up with the semi-trailer on a level surface is referred to as a ""high hook,"" where the king pin is not at its proper place on the fifth wheel (i.e. too far forward on the assembly) that if then taken onto the road can disconnect during transit with potentially catastrophic consequences.