Council Directive of 26 July 1971 on the approximation of the laws of the Member States relating to the braking devices of certain categories of motor vehicles and of their trailers (71/320/EEC) (repealed)

[F12.3.3. On motor vehicles constructed to tow trailers, the trailer shall be represented by a reservoir whose maximum relative pressure p (expressed in bars) is that which can be supplied through the feed circuit of the towing vehicle and whose volume V (expressed in litres) is given by the formula p × V = 20 R (R being the permissible maximum load, expressed in metric tonnes, on the axles of the trailer or semi-trailer).] U.K.