CDL General Knowledge TestDriving SafelyMedium
A commercial driver is conducting a pre-trip inspection of their vehicle. They notice that the air pressure in the primary air tank is building up much slower than usual, taking several minutes to reach the cut-out pressure. What could this indicate?
- AA leak in the air brake system.
- BAn over-performing air compressor.
- CA faulty air pressure gauge.
- DA fully charged air brake system.
Show answer & explanationAnswer & explanation
Correct answer: A. A leak in the air brake system.
A slow build-up of air pressure indicates that the compressor is working harder to overcome a loss of air, which is typically caused by a leak in the air brake system. A fully charged system would build up quickly, an over-performing compressor would build up faster, and a faulty gauge might show incorrect pressure but wouldn't affect the build-up rate.
Why the other options are wrong
- B. An over-performing compressor would build up air pressure faster than usual, not slower.
- C. A faulty air pressure gauge would display incorrect readings but would not directly affect the actual rate at which air pressure builds in the tanks.
- D. A fully charged system would show a normal, efficient pressure build-up, not a slow one.
Slow Air Pressure Build-Up
A significantly slower-than-normal air pressure build-up rate in a commercial vehicle's air brake system during a pre-trip inspection.
- Indicates a potential leak in the air brake system.
- Compressor works harder to maintain pressure.
- Can lead to insufficient braking power.
Memory trick: Slow air build-up means a sneaky escape.