Comments on the working documents submitted for the 80th session of GRRF
The deadline for the submission was at the 19th of June 2015.
The first document submitted was R55-10-02 about redefinition of Class S. The secretary commented that a small change was made in relation to the agreement at the 9th meeting of the working group. That was to include the class W that most likely will be approved during the 80th session of GRRF. This document was accepted by the working group without any changes.
The second document submitted was document R55-10-10. Concerning the proposal number 3 within the document R55-10-10 the working group had some comments on the distinction between hinged and rigid drawbars. This is not clear in the table 4. Hence the table was changed such that the row in the table that concerns drawbars was split into two rows. There is one for rigid drawbars and one for hinged drawbars. Furthermore a new column was added to handle the characteristic value Av. Through these changes the footnote to table 4 becomes obsolete. Hence it is removed. The changes are documented in the document R55-10-17. Furthermore it was observed in the fourth proposal within the working document that the definition of class W was unnecessary restricted to clevis type couplings. It shall be applicable to drawbar couplings in general. Hence the words “clevis type” were stricken out. This change was also documented in the document R55-10-17.
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)
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) ( )
Item 14 (2nd stage built) (R55-06-02)
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. 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)
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
The waiting list
According to the discussion on the future of this informal working group, the waiting list items are activated.
Item w1 (Approval based on worst case class B50x)(R55-07-19)
Item w2 (Approval based on worst case class B50x)(R55-07-19)
Item w3 (Alternative performance values)(R55-10-22)
Item w7 (Class H50)( )
Item w8 (Wedge angle)( R55-09-20)
Due to lack of time the remaining item were left to be processed later meetings.
New Items to the waiting list (R55-10-18)