scope:

This International Standard specifies the interchangeabilityrequirements of the various elements and dimensions for themechanical coupling of towing vehicles whose coupling is mountedforward and below to centre-axle trailers. It is applicable to roadtrains for the commercial transport of low-density, high-volumecargo of the greatest possible variety. It is also applicable tocorresponding equipment in cases where the same vehicle makes uppart of a road train having more than one trailer. It is notapplicable to dedicated or special combinations such as couplingsystems with an extensible drawbar; nor does it specify limitationson maximum gross mass and overall dimensions, which are generallylaid down by legislative requirements. Vehicle combinations whosecouplings form the subject of this International Standard (seeAnnex B for examples) are not interchangeable with those whosecouplings are rear-mounted (see ISO 11406).