CDL Combination Vehicles Practice Test Results

Question 1
49% answer correctly
Rearward amplification array(the "crack-the-whip" effect) is greater in combinations where there are __________ and __________ trailers.
More, longer
Fewer, longer
Fewer, shorter
More, shorter
Question 2
87% answer correctly
After hooking the trailer to the tractor you should check the fifth wheel connection by:
Backing the tractor quickly with the trailer brakes unlocked
Pulling the tractor ahead quickly with the trailer brakes unlocked
Pulling the tractor ahead slowly with the trailer brakes locked
Backing the tractor slowly with the trailer brakes locked
Question 3
53% answer correctly
What function does the service line perform?
Supplies air to the footbrake and trailer handbrake
Marks the maximum refill point for air tanks
Carries air controlled by the footbrake or trailer handbrake
Distributes air throughout the cab and to each of the trailers