Free CDL Combination Vehicle Practice Test

CDL Test Study Guide with Practice Questions
1. Combination vehicles are usually heavier, longer and require more driving skill than single commercial vehicles.
  1. True 
  2. False
2. More than half of truck driver deaths in crashes are the result of truck rollovers. Trucks turn over easier when fully loaded and are:
  1. Easy to get turned back right. 
  2. Five times more likely to roll over in a crash than empty rigs. 
  3. Ten times more likely to roll over in a crash than empty rigs.
3. The following two things will help prevent rollovers.
  1. Keep the cargo close to the front and drive slowly around turns. 
  2. Keep the cargo as close to the ground as possible and drive slowly around turns. 
  3. Keep the cargo to the back of the rig and drive the speed limit.
4. When you turn suddenly while pulling doubles, which trailer is most likely to turn over?
  1. The rear trailer is twice as likely to turn over as the tractor. 
  2. The front trailer is twice as likely to turn over as the tractor. 
  3. Each trailer is equally likely to turn over as is the tractor.
5. Why should you not use the trailer hand brake to straighten out a jackknifing trailer?
  1. Because the brake handle is too hard to reach. 
  2. Because the brakes on the trailer wheels cause the skid in the first place. 
  3. Because the brakes on the trailer wheels will not respond to the hand brake.
6. What is off tracking?
  1. When a vehicle goes around a corner, the rear wheels follow a different path than the front wheels. 
  2. When a vehicle goes around a corner, and the driver pulls off the road. 
  3. When a vehicle goes around a curve and turns back the other way.
7. What is a “trailer jackknife?”
  1. When the tires on a trailer blow out. 
  2. When the wheels of a trailer lock up and the trailer swings around. 
  3. When the wheels of a trailer lock up and the trailer pulls the tractor to a stop.
8. Should you swing wide to the left before starting a 90 degree turn?
  1. Yes 
  2. No
9. Why should you not use the trailer hand valve while driving?
  1. Because it won’t work as well as the foot brake. 
  2. Because you should use the parking brake. 
  3. Because of the danger of making the trailer skid.
10. Describe what the trailer air supply control does.
  1. It is used to supply the trailer with air, shut the air off and put on the trailer emergency brakes. 
  2. It is a yellow, six sided knob used to control the tractor protection valve. 
  3. It is a device used to keep the trailer behind the tractor.
11. Describe what the service line is for:
  1. To carry air to the parking brake to control the trailer brakes. 
  2. To carry air to a relay valve that allows the trailer brakes to be applied quickly. 
  3. To carry air to the cab of the rig to cool it.
12. What are other names for the Service Air Line?
  1. Control line or signal line 
  2. Straight line or control line 
  3. Curved line or signal line
13. What is the emergency air line?
  1. Air lines connecting the parking brake to the trailer brakes. 
  2. Air lines that control the emergency brakes of the tractor. 
  3. Air lines that control the emergency brakes on combination vehicles.
14. What is the emergency air line for?
  1. To engage the front brakes of the tractor in case of an emergency. 
  2. To engage the trailer brakes in case of air pressure loss. 
  3. To have extra air pressure in case you need it.
15. Why should you use chocks when parking a trailer without spring brakes?
  1. Because you don’t want the trailer rolling down a hill. 
  2. Because if the air pressure leaks away or down, there will be no brakes. 
  3. Because some states require checking of trailer wheels.

 

Answer Key

1. A 
2. C 
3. B 
4. A 
5. B 
6. A 
7. B 
8. B 
9. C 
10. A 
11. B 
12. A 
13. C 
14. B 
15. B