Check air brake system integrity (including air over hydraulic)

Step 1. Start the engine and charge up the braking system until the low pressure warning device turns off. Apply the brake several times until the low pressure warning device activates.

1. A visual or audible warning device connected to the brake system does not provide a warning to the driver when the air pressure is lowered to less than the following levels, unless the manufacturer specifies a different level:

• 420 kPa (60psi) for ADR 35 vehicles, or

• 350 kPa (50psi) for pre-ADR 35 vehicles

Step 2. Build the pressure up to its maximum level and note this pressure

1. The cut-out pressure is more than 1120 kPa (160psi), or less than 720kPa (100psi) unless other values are recommended by the manufacturer.

Step 3. With the engine running, apply the service brakes several times until the governor "cuts in"

The governor cut-in pressure is less than 550kPa (80psi), unless another value is recommended by the manufacturer.

Step 4. Recharge the system to maximum pressure. Stop the engine. Have the assistant apply and hold the service brake. Check around the vehicle for audible air leaks

1. Any air leak;
2. With the brake system fully charged, the engine stopped and the service brake applied, the air brake pressure drops more than 20 kPa (3psi) per minute. An additional drop per minute of 5 kPa is allowed for each trailer that may be attached.
   

Step 5. Release the service brake

1. With the engine stopped and the service brake released, the air brake pressure drops more than 15 kPa per minute. An additional drop per minute of 5 kPa is allowed for each trailer that may be attached.

Step 6. Fully apply and release the service brake four more times

1. After four more full applications of the service brakes the reservoir pressure drops to less than 50 % of the maximum value observed in Step

Step 7. Fully deplete the braking system by repeatedly applying the service brake. Observe the operation of the low pressure warning device (see "reason for rejection" (a)). Observe operation of spring brakes, if fitted.

1. Spring brakes activate before the low pressure warning device activates.

Step 8. Apply and release the parking brake

1. The parking brake is inoperative or is unable to be released at least once.

Step 9. Charge up the braking system by operating the engine at manufacturer's recommended speed, if necessary. Note the time it takes for the system to charge from zero to 80% of the maximum pressure (as noted in Step 2).

1. Time taken to charge from zero to 80% of maximum pressure exceeds 5 minutes.

Step 10. One at a time, open the drain valve of each reservoir for a sufficient time to notice a pressure drop on the pressure gauge(s)

1. Air reservoir drain valves are inoperative;
2. Excessive oil drains from the reservoir (this usually indicates a faulty compressor);
3. Where ADR 35 applies, the pressure in both sub-circuits falls when the reservoir of one of the sub-circuits is drained.

Note: Although it is usually a sign of neglected brake maintenance, excessive water in a reservoir is not a reason for rejection, provided that it is fully drained during the check.

Step 11. Where ADR35 applies and the vehicle is new, or has had major brake repairs involving plumbing, one sub-circuit should be fully drained and a check made that the brakes on the remaining sub-circuit operate when the service brake is applied (observe actuators or feel for pressure in flexible brake lines). The brake pressure should then be recharged and the test repeated for the other sub-circuit.

1. When the air-pressure in one (and only one) sub-circuit is fully drained any brake connected to the other sub-circuit fails to operate when the service brake is applied;
2. Where fitted, spring brakes apply when one sub-circuit is fully drained.