Combination #1
Combination Vehicles Practice Test | Tennessee 2026 #1 Page 3 of 3
Train for FREE online with our Tennessee CDL combination vehicle test. The official exam test consists of several obligatory parts, with all of them checking your knowledge of different blocks of road rules. If you need to obtain a TN combination license in 2026, practice as much as possible. Free sample tests published on our website will help you check and improve your knowledge and boost your grades. Please bear in mind that DMV requirements for issuing a combination license may vary from state to state.
20
16
20
15 . A tractor protection valve is:
A device that allows the battery to recharge efficiently.
On combination vehicles with air brakes, the tractor protection valve keeps air in the tractor or truck brake system, should the trailer develop a bad leak or break away from the tractor.
16 . An Anti-Lock Braking System (ABS):
Assists with the operation of brake lights.
The function of an Anti-Lock Braking System (ABS) is to prevent a vehicle's wheels from locking up during hard braking.
17 . If you use the trailer hand brake while your trailer is skidding, it will:
If you are experiencing a trailer jackknife, you can help your tires regain traction by releasing the brakes. Using a trailer hand brake while experiencing a skid will only cause the skid to continue.
18 . If a trailer is too high:
Coupling will be easier.
Before coupling together a tractor and a trailer, you should make sure the trailer is at the proper height. If the trailer is too low, the trailer nose may be damaged. If the trailer is too high, it may not be able to couple correctly.
19 . If a parked trailer does not have spring brakes, you should keep the trailer from moving by:
Parking on a slight incline.
If a parked trailer does not have spring brakes, wheel chocks should be used to prevent it from moving. Air brakes can only hold a parked trailer for as long as there is air pressure remaining in the air tanks, so wheel chocks will ensure safety.
20 . Test the tractor protection valve by:
Releasing air with the gas pedal.
