Practice question

How should you safely apply the trailer brakes only, for example to test the trailer's emergency function?

  1. With the foot valve
  2. By pulling the red 8-sided trailer air supply knob OUT, which exhausts the supply line and applies the trailer spring brakes
  3. Using only the parking brake
  4. Disconnecting the glad hands

Answer: B — By pulling the red 8-sided trailer air supply knob OUT, which exhausts the supply line and applies the trailer spring brakes

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