Practice question

For Wisconsin CDL air-brake testing, what is the purpose of the anti-compounding (modulator) valve in a dual air brake system?

It increases compressor speed
It prevents the service brakes and spring brakes from being applied at the same time, which could damage components or cause severe lockup
It cools the brake chambers
It bleeds the wet tank automatically

Answer: B — It prevents the service brakes and spring brakes from being applied at the same time, which could damage components or cause severe lockup

The correct answer is shown above. Try the full quiz for additional practice.