Pushing the brake pedal harder makes:
Correct. The foot valve modulates air pressure to the brake chambers in proportion to how hard you press the pedal.
CDL Practice Question #141
Category: Air Brakes
Why this question matters
This question is one of 71 in our Air Brakes bank. The reasoning above comes directly from the AAMVA CDL Manual, the source document used by every U.S. state DMV. Memorizing the underlying rule — not just the letter answer — is what separates passing on the first attempt from a return trip and another fee.