Practice question

What does a drain cock (drain valve) allow you to do on an air tank?

  1. Manually release air pressure from the tank to drain moisture
  2. Adjust the pressure at which the governor cuts out
  3. Control air flow to the primary circuit only
  4. Refill the tank with compressed air from an external source

Answer: A — Manually release air pressure from the tank to drain moisture

The correct answer is shown above. Try the full quiz for additional practice.

Practice more: CDL Air Brakes Knowledge Test →