R55_10_20-Proposal_worst case_2015_…

Submitted by the manufacturer from Poland
Proposal for an amendment to Regulation No. 55 (Mechanical couplings)
Determine worst case conditions for physical test.
Annex 6 § 1.1. (re arrange)
1.1. Samples of coupling devices shall be tested for both strength and function. Physical testing
shall be carried out wherever possible but unless stated otherwise the type approval authority
or technical service may waive a physical strength test if the simple design of a component
makes a theoretical check possible.
Theoretical checks may be carried out to determine worst case conditions. In all cases,
theoretical checks shall ensure the same quality of results as with dynamic or static testing. In
cases of doubt it is the results of physical testing that are overriding.
See also paragraph 4.8 of this Regulation.
Add new point
1.1.1. Theoretical checks may be carried out to determine worst case conditions design. The
relevant worst cases have to be identified by the manufacturer and the technical
service. The corresponding physical tests shall be representative for the entire product
range concerned. When in doubt about the worst cases the technical service/type
approval authority may require more physical tests.
Usually when applying for approval one sample is chosen, but not always it is the worst
case from the approved coupling devices or components to be approved.
E.g. in the approval of coupling head: one Ø50 mm diameter coupling head is chosen.
However, no other coupling head variants (different according to shape and dimensions of
connectors, as well as placement, size and shape of mounting holes) listed in the
application for approval are tested.
Endurance tests of coupling heads with connector diameter different than Ø50mm, carried
out according to the Regulation 55 (Annex 6; p. 3.2.1), within one type, might be negative
for different variation of product. It is highly probable that such state of affairs is
maintained since the beginning of production – it can be alleged that the mentioned
coupling head types did not undergo any control or testing by technical services or
approval authorities.
The lower endurance of coupling head can have big influence of safety of users of the
mechanical coupling devices and components and general road safety.
E.g. it is common that an application for type approval of e.g. a class B coupling head
includes quite a few variants e.g. with respect to attachments etc. In order to avoid
unnecessary and costly testing worst case variants need to be identified. It may at times be
difficult to identify those worst case variants without theoretical assessments. This
proposal is aimed at highlighting the given possibility to use theoretical assessment to
identify the worst cases.
V.3 2015.06.1