Item 2 (Auxiliary usage Class A) (R55-03-09, R55-03-10, R55-03-11, R55-04-05, R55-04-06, R55-04-07, R55-05-17, R55-06-02, R55-07-12)
Mr. Westphäling reported that he had googled to find any information about accidents with bicycle carrier mounted on a trailer hitch. Using the keywords “fahrradträger verloren” he got a lot of hits. It is hard to judge from these articles whether it is a problem with the hitch per se or with the bicycle carrier itself. However some cases seem to indicate that there is fatigue of the hitch. The statistics in this area is very poor. Usually when there is an accident with a car running in to a lost bicycle carrier there is not focus on the hitch of a vehicle that lost that bicycle carrier. Hence you can expect an under reporting in this area.
Within the next three month the DIN/VDA will post a New Work Item Proposal with ISO. This proposal will address the auxiliary usage of trailer hitches. Mr. Westphäling will follow the development and report back to our working group. Next meeting
Item 12 (Clearance around drawbar coupling) ( )
The picture in annex 7 § 1.3.6. shall remain as is. Item closed.
Item 14 (2nd stage built) (R55-06-02)
Mr. Westphäling showed the product “Space extender” produced and marked by the company SMV. http://www.spaceextender.com/ . This is an extreme illustration of “second stage built” The experts were very puzzled with this design. However it was apparently approved under regulation 55. The discussion on this item showed that there were ties to agricultural applications as well. We have at earlier meetings discussed mobile homes in the context. However no solid proposal how to go forward with this has evolved. The discussion this time took an angle towards what is coupling equipment. Mr. Westphäling will follow up and report. Next meeting
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
Item 21 (Limiting cases for the usage of certified characteristic values) (R55-04-11, R55-05-05, R55-06-09, R55-07-06, R55-07-14, R55-08-03, R55-08-04, R55-08-05, R55-09-04, R55-09-05, R55-09-11, R55-09- 13, R55-10-03: R55-10-04; R55-10-05; R55-10-06; R55-10-07; R55-10-08; R55-10-15)
At the previous meeting Mr. Stokreef requested more of the background information to the ISO18868:2013 standard. In order to respond to that request Mr. Svensson had uploaded the documents R55-10-03: R55-10-04; R55-10-05; R55-10-06. The last of those documents was a history summary over the work with that standard going back to 2002. The document R55-10-07 was a summary of many recent measurements of coupling forces in different vehicle combinations. There is also a comparison with the requirements as calculated using the ISO18868:2013. It could be noted that the measure peak forces only at on instance came close to the fatigue test load corresponding to the performance required.
Mr. Westphäling at the 9th meeting argued that road conditions in Germany are worse than in Australia. To this meeting Mr. Svensson had gathered information that showed that the German Autobahn does not have worse conditions than the Australian roads. Hence the measured forces and the experience over 30 years supporting the ISO18868 are valid. Mr. Stokreef was not present but had prior to the meeting expressed support for the proposal for this item. Mr. Westphäling argued that different engine power and and brakes requirements would the still make the proposal questionable. In response to that Mr. Svensson showed the diagram in the document R55-10-07. There it could be seen that the real high coupling forces is generated neither by traction nor by braking but through interaction between unevenness in the road and the geometric layout of the vehicle combination. Hence the difference in engine power and braking performance is not a significant factor. While support for the proposal is converging Mr. Westphäling wanted to the next meeting to challenge OEM:s and trailer manufactures for more measurements. Mr. Alguëra was doubtful whether there are any better measurements available. Next meeting