Item 20 (Heavy transports) (R55-02—-13, R55-04—-08, R55-04—-12, R55-05-01, R55-05-06, R55-05-20, R55-05-21, R55-05-22, R55-07-18, R55-08-13, R55-09-06, R55-10-08; R55-10-09; R55-10-13)
Mr. Svensson had made some kinematic investigations to get some indications on speed dependence of coupling forces. This showed the peak longitudinal accelerations when traversing a sinusoidal wavy road to be related to the speed squared. Bearing in mind that this is an indication of the speed dependence of the most important coupling force generating mechanism it is a good basis for the discussion. It should be observed that this study is kinematic. It will in reality be influenced by the flexibility and masses in the vehicles involved. Mr. Svensson also pointed to the document R55-09-06 where the speed dependence of the range and standard deviation are plotted as dependent of speed. The dependence is very clear. Over long time VBG, according to Mr. Svensson, has applied a rule where the forces are dependent on square root of the speed. Based on these different observations Mr. Svensson proposed a linear dependence between 36 km/h and 80 km/h. Below 36 km/h the reduced value at 36 km/h applies.

Mr. Alguëra commented that his company had checked the proposal against their proposal. From that check he expressed a support for the proposal. Mr Tagliaferri also expressed support. Mr. Conrads was questioning whether the base speed should be 90 km/h rather than 80km/h. Mr Westphäling was hesitant and referred to Australian conditions. Mr. Mátyás pointed out the conditions are such that reducing requirements would at times kill the coupling in very short time of operation. In response to that it was concluded that the utilizing speed dependence as a mean to encompass heavy loads is only applicable to commercial road vehicles where the coupling equipment is designed for a base speed of 80 km/h. The experts will consider the proposal to the next meeting. Next meeting

Since last meeting no new facts have been put forward. Delegates realized the benefit of having such an agreed handling of heavy transports. The chairman argued whether it was correct to have this kind of rules in the type approval regulations. Mr. Svensson argued towards that, that it had already since long been recognized by the legislator that couplings are in this respect a bit special as being so to speak the interface between two vehicles. A performance value as verified by the procedures in Annex 6 has no value if you do not at the same time tell how it may be utilized. Similar arrangements may be found in other regulations such as tires for instance. This proposal is just expanding or complementing what is already found in the regulation. Most countries have their own rules set up. It was agreed that Mr. Svensson shall elaborate a more finalized proposal to the next meeting based on the R55-10-13.