sch.3-sec.21Couplings for B-doubles and road trains

sch.3-sec.21 Couplings for B-doubles and road trains

A fifth wheel coupling used to connect a towing vehicle to a semitrailer used in a B-double or road train must not be built with a pivot that allows a semitrailer to roll relative to the towing vehicle. However, subsection (1) does not apply to a fifth wheel coupling if— the semitrailer design requires torsional stresses to be minimised; and the roll axis of the fifth wheel coupling is above the surface of the coupler plate of the coupling; and the degree of rotation allowed around the roll axis of the fifth wheel coupling is restricted to prevent roll instability. A trailer with only 1 axle group or a single axle, other than a semitrailer or a converter dolly, that is used in a road train must not have a coupling fitted at its rear. (sch.3-sec.21-ssec.1) A fifth wheel coupling used to connect a towing vehicle to a semitrailer used in a B-double or road train must not be built with a pivot that allows a semitrailer to roll relative to the towing vehicle. (sch.3-sec.21-ssec.2) However, subsection (1) does not apply to a fifth wheel coupling if— the semitrailer design requires torsional stresses to be minimised; and the roll axis of the fifth wheel coupling is above the surface of the coupler plate of the coupling; and the degree of rotation allowed around the roll axis of the fifth wheel coupling is restricted to prevent roll instability. (sch.3-sec.21-ssec.3) A trailer with only 1 axle group or a single axle, other than a semitrailer or a converter dolly, that is used in a road train must not have a coupling fitted at its rear.

• (a) the semitrailer design requires torsional stresses to be minimised; and
• (b) the roll axis of the fifth wheel coupling is above the surface of the coupler plate of the coupling; and
• (c) the degree of rotation allowed around the roll axis of the fifth wheel coupling is restricted to prevent roll instability.