Air brakes take longer to work than hydraulic brakes because:
Correct. Brake-lag in air systems comes from the time air takes to travel through lines and reach all the brake chambers — typically 0.4 seconds added to perception/reaction time.
CDL Practice Question #128
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.