CDL Combination Vehicles TestCombination Vehicle Air BrakesMedium

During a pre-trip inspection of a combination vehicle, you notice that one of the air tanks is actively leaking air, and the air compressor is constantly running. What is the most appropriate immediate action?

  1. AIncrease the engine RPMs to help the compressor keep up with the leak.
  2. BAttempt to patch the leak temporarily and then continue the trip.
  3. CContinue the trip, but monitor the air pressure gauges closely.
  4. DImmediately take the vehicle out of service and arrange for repairs.
Show answer & explanation

Correct answer: D. Immediately take the vehicle out of service and arrange for repairs.

A constant air leak with the compressor running continuously indicates a severe problem that can lead to brake failure. The vehicle must be taken out of service immediately.

Why the other options are wrong

  • A. Increasing RPMs will put more strain on the compressor and engine but will not fix the leak or make the vehicle safe.
  • B. Temporary patches are not reliable for air brake systems and do not address the underlying safety issue.
  • C. Continuing the trip with a significant air leak is extremely dangerous and could lead to complete brake failure.

Critical Air Leak Action

If a significant air leak is detected in a combination vehicle's air brake system, rendering the braking system unsafe, the vehicle must be immediately taken out of service.

  • Constant compressor running signals a major leak.
  • Loss of air pressure leads to brake failure.
  • Safety is paramount; do not operate unsafe vehicles.

Memory trick: Leak + Constant Compressor = Stop, Repair, No More.

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