The new system of type MT054 consists of four basic components (ball head, clamping cage, cross member and side plate), which are bolted to the chassis or chassis extension as an assembly. This provides maximum flexibility. The ball coupling can be mounted either as a detachable version, with a fixed ball bar or as a four-hole flange coupling, which makes optimum use of the installation space under the body in every motor home. The cross member is available in all standard widths for AL-KO chassis and SAWIKO chassis extensions. And the side plates are available for all common variants of the existing AL-KO cross member for the AL-KO chassis. In addition, further assembly positions can be realised using the modular system.