Division 2.3.3

On vehicles constructed to tow vehicles, the towed vehicle shall be represented by an air reservoir whose maximum relative pressure p (expressed in kPa/100) is that which can be supplied through the feed circuit of the tractor and whose volume V (expressed in litres) is given by the formula p × V = 20 R (R being the permissible maximum mass, expressed in tons, on the axles of the towed vehicle).