UN R90 specifies one minimum shear strength requirement for brake shoe assemblies and one requirement for brake pad assemblies in Regulation No. 90 via a reference to ISO 6312. However, ISO 6312 specifies test methods for hot and cold shear tests. Therefore, GRRF is requested to clarify whether the strength requirements are for both hot and cold shear.
28. The secretariat introduced GRRF-81-27 containing the request for clarifications of paragraph 5.2.2.1.1 in Regulation No. 90. Only one minimum shear strength requirement is specified for brake shoe assemblies and one requirement for brake pad assemblies in Regulation No. 90 and it is therefore requested that clarification be provided if these requirements are for both cold and hot shear because ISO 6312 specifies methods for both cold and hot shear tests. GRRF confirmed that Regulation No. 90 requested that the test, according to the mentioned ISO standard, has to be run at ambient temperature only. Several experts noted that a general review of Regulation No. 90 would be useful in order to minimize interpretation issues. Following discussions, the expert from Spain prepared and presented ToR for a SIG of experts to explore whether the issues related to the interpretation of the Regulation were minor and could be managed by GRRF or whether they are significant and would require the establishment of a specific IWG. GRRF agreed with the proposal and endorsed GRRF-81-33.
67. The secretariat introduced GRRF-81-27 under agenda item 6 (see para. 28 above).