10 questions, graded as you go, with the reason for every answer. No sign-up.
What this covers
Systems
Air lines
Warnings
Air supply
Brake fade
Endurance brakes
ABS
Jack-knifing
Coupling
Spring brakes
Stopping distances
Following distances
Sample questions
The low air pressure warning buzzer sounds while driving. What should the driver do?
Continue slowly to the depot
Pump the brake pedal to build air
Stop safely as soon as possible
Switch to the exhaust brake only
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C. Stop safely as soon as possible
Low pressure means the brakes may soon be ineffective or may apply by themselves, so the driver should stop in a safe place and have the fault found. Pumping the pedal uses up the air that remains.
Reference: DVSA Official Guide to Driving Goods Vehicles, braking systems
Why should air reservoirs be drained if the vehicle has no automatic drain valves?
To lower the working pressure
To remove moisture that has collected
To cool the compressed air
To reset the low-pressure warning
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B. To remove moisture that has collected
Compressing air produces condensation, which collects in the tanks, can corrode components and may freeze in the lines in winter. Draining does not alter the working pressure, which the governor controls.
Reference: DVSA Official Guide to Driving Goods Vehicles, braking systems
In freezing weather, what is the main danger from moisture in the air brake system?
The compressor overheating
Air pressure rising too high
Brake linings wearing faster
Ice blocking valves and pipes
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D. Ice blocking valves and pipes
Water in the system can freeze and block valves or pipes, leaving brakes that will not apply or will not release. Air dryers and regular draining are the defence against it.
Reference: DVSA Official Guide to Driving Goods Vehicles, braking systems
