Heavy Vehicle (Vehicle Standards) National Regulation
sch.3-sec.12Air brakes in a B-double or road train—least favoured chamber
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sch.3-sec.12 Air brakes in a B-double or road train—least favoured chamber
The pressure in the least favoured chamber of the braking system of a heavy motor vehicle used in a B-double or road train that is fitted with air brakes that use compressed air must comply with subsections (2) and (3) when the air pressure before the brakes are applied is not more than— the average of the maximum and minimum pressures in the operating pressure range specified by the vehicle’s manufacturer; or if there is no manufacturer’s specification—650kPa. The pressure must reach at least 420kPa within— for a B-double—1 second after the rapid and complete application of the foot-operated brake control; or for a road train—1.5 seconds after the rapid and complete application of the foot-operated brake control. After the brakes have been fully applied, the pressure must fall to 35kPa, or the pressure at which the friction surfaces cease to contact each other, within— for a B-double—1 second after the release of the foot-operated brake control; or for a road train—1.5 seconds after the release of the foot-operated brake control. In this section— least favoured chamber , in relation to a heavy motor vehicle used in a B-double or road train, means the brake chamber with the longest line to the treadle valve in the heavy motor vehicle. (sch.3-sec.12-ssec.1) The pressure in the least favoured chamber of the braking system of a heavy motor vehicle used in a B-double or road train that is fitted with air brakes that use compressed air must comply with subsections (2) and (3) when the air pressure before the brakes are applied is not more than— the average of the maximum and minimum pressures in the operating pressure range specified by the vehicle’s manufacturer; or if there is no manufacturer’s specification—650kPa. (sch.3-sec.12-ssec.2) The pressure must reach at least 420kPa within— for a B-double—1 second after the rapid and complete application of the foot-operated brake control; or for a road train—1.5 seconds after the rapid and complete application of the foot-operated brake control. (sch.3-sec.12-ssec.3) After the brakes have been fully applied, the pressure must fall to 35kPa, or the pressure at which the friction surfaces cease to contact each other, within— for a B-double—1 second after the release of the foot-operated brake control; or for a road train—1.5 seconds after the release of the foot-operated brake control. (sch.3-sec.12-ssec.4) In this section— least favoured chamber , in relation to a heavy motor vehicle used in a B-double or road train, means the brake chamber with the longest line to the treadle valve in the heavy motor vehicle.
- (a) the average of the maximum and minimum pressures in the operating pressure range specified by the vehicle’s manufacturer; or
- (b) if there is no manufacturer’s specification—650kPa.
- (a) for a B-double—1 second after the rapid and complete application of the foot-operated brake control; or