Practice question

For the Washington CDL Air Brakes knowledge test, what is the role of the foot valve (also called the treadle or service brake valve)?

  1. It locks the parking brake
  2. It supplies air to the brake chambers in proportion to how hard the driver presses the pedal
  3. It drains water from the tanks
  4. It controls the trailer air supply

Answer: B — It supplies air to the brake chambers in proportion to how hard the driver presses the pedal

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

Practice more: Washington CDL Air Brakes Test Practice Questions - Washington Commercial Driver License (CDL) Air Brakes Knowledge Test Exam →