Heavy Vehicle (Vehicle Standards) National Regulation

If a heavy motor vehicle used in a B-double or road train is fitted with air brakes that use compressed air, the heavy motor vehicle’s braking system must comply with subsections (2) and (3) when—

the air pressure in the braking system is measured in an 800mL vessel connected by a 2m pipe with a bore of approximately 13mm to the coupling head of the braking system; and

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 air pressure in the braking system must reach at least 420kPa within 400 milliseconds after the rapid and complete application of the foot-operated brake control.

After the air brakes have been fully applied, the air pressure in the braking system must fall, within 0.5 seconds after the release of the foot-operated brake control, to 35kPa.

In this section—coupling head, of a heavy motor vehicle’s braking system, means the part of the braking system that connects the system to a vehicle being towed by the heavy motor vehicle.