Heavy Vehicle (Vehicle Standards) National Regulation

If a heavy trailer has air brakes, its braking system must include at least 1 air storage tank.

If a heavy trailer has vacuum brakes, its braking system must include at least 1 vacuum storage tank.

An air storage tank or vacuum storage tank in the braking system of a heavy trailer must—

be constructed to give an audible or visible warning to the driver of the towing vehicle, while in the normal driving position, of a lack of air or vacuum that would prevent the brakes from meeting the performance standards of section 87; and

be safeguarded by a check valve or other device against loss of air or vacuum if the supply of air or vacuum fails or leaks.