Practice question

What does pulling out the red trailer air supply control do?

Releases all trailer brakes
Opens fifth wheel jaws
Shuts off trailer air and applies trailer emergency brakes
Connects the electrical cord

Answer: C — Shuts off trailer air and applies trailer emergency brakes

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

Practice more: Missouri CDL Combination Practice Questions - Missouri CDL Combination Vehicles Test Exam →