Home › CDL Practice Tests › Combination Vehicles Questions › Question 13
When should you connect the air lines and electrical cord during coupling?
- A.Before backing under, while the tractor is still far away
- B.Only after driving the first mile
- C.After the tractor is securely coupled and backed under the trailer, before raising the landing gear for travel
- D.Never, they connect automatically
Correct answer
C. After the tractor is securely coupled and backed under the trailer, before raising the landing gear for travel
Why
Lines are connected once the units are mechanically joined so gladhands and the plug can be reached safely. Checking lights and air flow after connecting catches crossed or leaking lines before departure.
Manual topic: Combination Vehicles - Coupling · From the Combination Vehicles practice bank (CV-013).