In the case of semi -trailer tractors, the dummy coupling is installed on the rear wall of the driver’s cab, on centre axle trailers and full draw bar trailers a suitable position on the front wall of the trailers must be found, and the dummy couplings mounted in such a way as to ensure that the connected air lines cannot become loose.

The support surface for the sealing ring of the coupling head must be cleaned. Care must be taken to ensure that the vent hole is not blocked. Check the mounting of the dummy coupling, ensure the sealing surfaces and the vent hole are clean. Once the coupling heads have been uncoupled, they must be placed and locked onto the dummy coupling.