If one side of a dual air system loses pressure, which statement best describes the braking impact?

• A. Brakes on both sides fail completely
• B. Front or rear brakes may not function fully
• C. Emergency brakes will compensate perfectly
• D. Brake drums will instantly cool down

Answer: (B)

Dual air brake systems use two independent circuits to apply the brakes. If pressure is lost on one side of the system, the brakes on that side won’t be able to apply as strongly, so braking is reduced on that axle rather than failing everywhere. The other side still has pressure and can function, but the braking force becomes uneven. You’ll often notice the vehicle pulling toward the side with weaker braking and an overall longer stopping distance. Emergency or backup brakes aren’t able to perfectly compensate for this uneven loss, and they don’t restore full braking on the affected side. So the best description is that the front or rear brakes on the affected side may not function fully.