Want to review your answers at any time?
Submit your email at the end of the test.
Combination Vehicle Endorsement Test
Question 1 |
What will happen if the service air line comes apart while you are driving a combination vehicle?
the trailer's air tank will exhaust through the open line | |
the emergency trailer brakes will come on | |
nothing is likely to happen until you put on your brakes | |
nothing at all is going to happen |
Question 2 |
When uncoupling, it's a good practice to
couple the glad hands to dummy couplers | |
couple the glad hands together | |
hang the electrical cable with the plug end down | |
all of the above are acceptable |
Question 3 |
If you cross your air lines on a new trailer with spring brakes...
you won't have any operational brakes | |
you'll have no way of knowing there's a problem | |
you won't be able to release the trailer brakes | |
you won't be able to release the tractor brakes |
Question 4 |
When traveling under 40 mph, you should follow other vehicles...
With a distance of one second for every twenty feet of your vehicle length | |
Only during the day | |
With a distance of one second for every ten feet of your vehicle length | |
As close as possible so others don't cut in |
Question 5 |
In order to supply air to the trailer, you must first...
Cross the air lines to check for leaks | |
Stop engine so you can hear the brakes | |
Pull out the "air supply' knob | |
Push in the tractor protection valve |
Question 6 |
If one of the glad hands on your blue air line is missing a seal...
it's not a major problem and you should continue coupling | |
you might end up with a service line air leak | |
you could experience an emergency line air leak | |
take one off the red air line and use that as a temporary replacement |
Question 7 |
When you inspect the coupling, check to ensure that...
there's a little slack in the air lines | |
there's no slack in the air lines | |
the landing gear handle is hanging free | |
the electrical cable is unplugged |
Question 8 |
What is the correct setup for shut-off valves?
All shut-off valves should be closed. | |
All shut-off valves should be open. | |
The rear trailers shut-off valves open and the front closed | |
The front trailers shut-off valves open and the rear closed |
Question 9 |
If the trailer is too high when you try to couple, what may happen?
It may not couple correctly. | |
The trailer may tip and flip over. | |
The king pin may fall off. | |
All of these |
Question 10 |
What is the emergency air line for?
It supplies air to the tractor air tanks and controls the emergency brakes on combination vehicles. | |
None of these | |
It supplies air to the trailer air tanks and controls the service brakes on combination vehicles. | |
It supplies air to the tractor air tanks and controls the service brakes on combination vehicles. | |
It supplies air to the trailer air tanks and controls the emergency brakes on combination vehicles. |
Question 11 |
Two things that are important to prevent rollover are _______.
....the weight and length of the vehicle | |
...keeping the cargo center of gravity as high as possible and driving slowly around turns | |
...keeping an evenly loaded trailer and keeping properly inflated tires | |
...keeping the cargo as close to the ground as possible and driving slowly around turns |
Question 12 |
The trailer hand valve should be used...
Only to test the trailer brakes | |
Both B & C above | |
Only when parking | |
Only at highway speeds |
Question 13 |
Which one of the following statements about tractor protection valves is NOT true?
It is controlled by the trailer air supply valve in the cab | |
It keeps air in the tractor in the event the trailer air leaks | |
When it closes it allows air to leak from the tractor line | |
It will close automatically if air pressure is low |
Question 14 |
Which of the following is the definition of "off-tracking"?
When the rear wheels follow a different path than the front wheels | |
None of these | |
When the rear wheels go into a skid and the front wheels continue in a straight line | |
When the front wheels go one direction and the trailer wheels go in the other direction |
Question 15 |
After coupling, there should be _____ space between the upper and lower fifth wheel
None of these | |
...1/4 inch | |
...1/16 inch | |
...1/32 inch | |
...1/8 inch |
Question 16 |
Which trailer is most likely to turn over when you turn suddenly while pulling double trailers?
The rear trailer | |
The front trailer | |
Neither trailer is more likely to turn over. | |
Both trailers |
Question 17 |
Before driving, you need to raise the landing gear only until it just lifts off the pavement.
True | |
False |
Question 18 |
You can damage the landing gear if you...
back under the trailer at an angle | |
back under the trailer in a straight line | |
align the tractor and trailer | |
position the trailer kingpin in the center of the fifth wheel |
Question 19 |
Which one of the following is controlled by the foot brake?
The hose coupler | |
The emergency air line | |
The service air line | |
The shut off valve |
Question 20 |
To straighten out a jackknifing trailer, why should you NOT use the trailer hand brake?
The tractor wheels caused the skid in the first place. Once the trailer wheels grip the road again, the trailer will start to push the tractor and straighten out. | |
This is the only time that you should use the trailer hand brake. | |
None of these | |
The trailer wheels caused the skid in the first place. Once the trailer wheels grip the road again, the trailer will start to follow the tractor and straighten out |
List |
About the Combination Vehicles CDL Test
The Combination Vehicles test:
- 20 questions.
- You need 16 correct answers (80%).
- You may be timed. Time limit varies by state.
For those of you going for the Class A CDL, you will have to pass the written test covering information on combination vehicles. A combination vehicle is defined as any tractor-trailer set up, including a tractor with a single trailer, double trailers, triple trailers, and straight truck with a trailer.
While this test is separate from the general knowledge test, these are the vehicles that Class A drivers want to drive. The information tested in the Combination Vehicles test will only qualify you for common combination vehicles, not for doubles and triples. There’s a separate test for those!
The fact that most combination vehicles are typically heavier, longer, and require greater driving skill than single vehicles means that you will need specialized knowledge to safely operate one.
Now, don’t get in a rush to just buzz through the exam. Make sure you read and understand each question before selecting your answer because there are a lot of peculiarities with combination vehicles that can make them very dangerous.
Topics covered in the Combination Vehicles Test are as follows:
- Safe driving
- Rollover risk
- Railroad-highway crossings
- Preventing skids
- Turning
- Backing
- Combination vehicle air brakes
- Antilock brake systems
- Coupling and uncoupling
- Inspecting a combination vehicle
Be ready to answer a variety of questions. Why should you not use the trailer hand brake to straighten out a jack-knifing trailer? What is off-tracking? Why should you use chocks when parking a trailer? How can you test the trailer service brakes?
