part limbs 36 of the coupling module 20 are connected by the floor web 39 as in particular results in the view of fig7 reference is made to fig5 in the following for the divisibility of the coupling module head part from the coupling module base part it can be recognized from this that the head part limb 34 of the coupling module head part 26 has a first coupling plate 37 a and the base part limb 36 has a second coupling plate 37 b the head part limb 34 furthermore has a spigot 35 in the region of the first coupling plate 37 a with a receiver 35 a for the spigot 35 being provided in the region of the second coupling plate 37 b of the base part limb 36 for the assembly of the coupling module head part 26 with the coupling module base part 32 the spigot 35 now moves into the receiver 35 a for the spigot with the two coupling plates 37 a and 37 b being connected to one another by screws 37 c it has already been pointed out that the coupling module 20 has a pivot frame 27 and an adapter frame 28 with the pivot frame 27 being connected to the adapter frame 28 by a pivot device 40 it is important here that the pivot device 40 is only located in the region of the coupling module base part 32 this means that the pivoting of the pivot frame relative to the adapter frame.