National Transport Commission (Road Transport Legislation – Vehicle Standards) Regulations 2006
140Air brakes in a B‑double or road train: least favoured chamber
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140 Air brakes in a B‑double or road train: least favoured chamber
(1) In this rule:
least favoured chamber means the brake chamber with the longest line to the treadle valve in the prime mover.
(2) The pressure in the least favoured chamber of the braking system of a B‑double or road train with brakes that operate using compressed air must comply with subrules (3) and (4) when the air pressure before the brakes are applied is not under: (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—650 kilopascals. (3) The pressure must reach at least 420 kilopascals within: (a) for a B‑double—1 second after the rapid and complete application of the foot‑operated brake control; or (b) for a road train—1.5 seconds after the rapid and complete application of the foot‑operated brake control. (4) After the brakes have been fully applied, the pressure must fall to 35 kilopascals, or the pressure at which the friction surfaces cease to contact each other, within: (a) for a B‑double—1 second after the release of the foot‑operated brake control; or (b) for a road train—1.5 seconds after the release of the foot‑operated brake control.