Proposal to delete the contents of Annex 9 on parking brake systems equipped with a mechanical brake-cylinder locking device due to obsolescence.

Proposal to clarify the intent of the selected paragraphs to ensure that systems with with one service brake meet braking performance requirements using only that brake system (i.e, without any assistance from the secondary brake system). There had been an interpretation that for systems with two service brakes each brake had to meet the requirements which would result in higher stringency levels than intended by the requirement for single brake systems.

The proposal also clarifies the parts of the braking system that should be considered with respect to hydraulic brake and mechanical transmissions and further clarifies that the test procedures are designed to simulate a brake failure rather than produce one.

Correction of errors in the proposal of the ad hoc expert group on transitional provisions to clarify and update these terms within the light braking regulation, including provisions for extensions of type approvals granted according to the antecedent requirements of the original approval. These amendments also relate to the transfer of brake-related telltale provisions to UN R121. The proposal notes the deletion of two pictograms referencing electronic stability controls (ESC).