CDL
Combination Vehicles
Practice Test

Question 3 of 3
You`re hooking a tractor to a trailer. After connecting the air lines and before backing under the trailer you should:
Activate air supply to the trailerarray(s) then lock the trailer brakes
Be sure not to activate air supply to the trailerarray(s) to prevent damage to the air delivery system
Pull forward to test the strength of the air line connection
Activate air supply to the trailerarray(s) and leave the trailer brakes unlocked