Practice question

When uncoupling a trailer with air brakes, what should you do BEFORE disconnecting the glad hands?

Drain all air tanks
Apply the trailer parking (spring) brakes by pulling the red trailer air supply knob out, then disconnect the glad hands
Start the engine
Apply the foot brake hard

Answer: B — Apply the trailer parking (spring) brakes by pulling the red trailer air supply knob out, then disconnect the glad hands

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