Alabama CDL General Practice Test

Air brake systems introduce a delay known as brake lag, which makes stopping distances longer than hydraulic brakes. When you press the brake pedal, it takes time for the air to travel through the lines, build pressure in the brake chambers, and apply the brakes. That delay adds to the distance the vehicle travels before it starts to slow down, and the total stopping distance becomes longer than with hydraulic systems that respond more immediately. Hydraulic brakes apply force through fluid pressure directly to the brake mechanisms, so they tend to respond faster and with less lag. Because of this lag, the overall stopping distance for air brakes is usually greater, especially at higher speeds. The other statements aren’t accurate because they imply no difference, exact equality, or that lag doesn’t affect stopping distance, which isn’t true.