Division 3.1.1.2

F1In the case of a tractor authorized to tow an unbraked vehicle of categories R or S, the required minimum combination performance, as required in point 3.1.1.2.1, shall be attained with the unbraked towed vehicle coupled to the tractor and with the unbraked towed vehicle laden to the maximum mass declared by the tractor manufacturer.

The combination performance shall be verified by calculations referring to the maximum braking performance actually achieved by the tractor alone during the Type-0 test with the engine disconnected for the laden and unladen tractor (optionally also for a partially laden condition defined by the tractor manufacturer), using the following formula (no practical tests with a coupled unbraked towed vehicle are required):

Where:

d_{M + R}

calculated mean fully developed deceleration of the tractor when coupled to an unbraked towed vehicle, in m/s²,

d_M

maximum mean fully developed deceleration of the tractor alone achieved during the Type-0 test with engine disconnected, in m/s²,

P_M

mass of the tractor (if applicable, including any ballast and/or supporting load)

P_{M_laden}

mass of the tractor, laden

P_{M_par_laden}

mass of the tractor, partial laden

P_{M_unladen}

mass of the tractor, unladen

P_R

part of the maximum mass borne by the axle(s) of a towed vehicle without a service brake which may be coupled (as declared by the tractor manufacturer)

P _{M + R}

combination mass (mass P _M + declared unbraked towed vehicle mass P _R )