Practice question

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

It locks the parking brake
It supplies air to the brake chambers in proportion to how hard the driver presses the pedal
It drains water from the tanks
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

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