How does brake lag affect stopping a combination vehicle compared with a straight truck?

• A.The air signal takes time to reach the trailer brakes, so a combination vehicle travels farther before full braking begins
• B.Brake lag only exists on hydraulic brake systems
• C.Combination vehicles have no brake lag because the trailer tanks are larger
• D.Brake lag shortens stopping distance at highway speed

Why

Air needs time to travel through the lines to the trailer, and that delay adds distance before the trailer brakes apply fully. Anticipating stops and braking early makes up for the lag built into every air-braked combination.

Manual topic: Combination Vehicles - Skids and Jackknifing · From the Combination Vehicles practice bank (CV-138).

Practice this subject as a full test

More Combination Braking, Skids & Jackknife Prevention questions

• Why is an empty trailer more likely to jackknife under hard braking than a loaded trailer?
• What is usually the first visible sign that your trailer is starting to jackknife?
• Your trailer wheels have locked and the trailer is skidding sideways because you braked too hard. What should you do to help it recover?
• What is the difference between a tractor jackknife and a trailer jackknife?
• Why should you tap your brakes lightly well before a planned stop when traffic is following you?