Skip to Content

Free Combination Vehicle Practice CDL Test

Use this free Combination Vehicle commercial drivers license practice test to prepare yourself to get your CLP (commercial learner's permit). To learn more about Roehl's paid CDL training, view our Get Your CDL page or apply now. See All CDL Practice Test Ratings.

Question 1 of 40

When should you use the hand valve to park a combination vehicle?


 
 

Question 2 of 40

A fully loaded rig is _____ times more likely to roll over in a crash than an empty rig.


 
 

Question 3 of 40

Which type of truck-trailer combination has the greatest chance of a 'crack-the-whip' rollover?


 
 

Question 4 of 40

After you lock the kingpin into the fifth wheel, you should check the connection by pulling:


 
 
 

Question 5 of 40

What is the other name for the shut-off valves?


 
 
 

Question 6 of 40

What is the first thing you should do to prevent a trailer skid?


 
 
 

Question 7 of 40

You should not use the trailer hand valve while driving because...


 
 
 

Question 8 of 40

When following behind other vehicles, you should follow:


 
 
 

Question 9 of 40

A trailer jackknife is likely to happen when:


 
 
 

Question 10 of 40

What is the emergency air line?


 
 
 

Question 11 of 40

What is the fastest and best way to recognize that your trailer has started to skid?


 
 
 

Question 12 of 40

If your trailer begins to skid, you should:


 
 
 

Question 13 of 40

Which type of vehicle is harder to control while stopping?


 
 
 

Question 14 of 40

When hoses are not in use, why should the trailer glad hands be locked together or attached to dead end or dummy couplers?


 
 
 

Question 15 of 40

If the tractor protection valve malfunctions, which of the following may occur?


 
 
 

Question 16 of 40

On older trailers, what will happen if the emergency and service air lines are crossed?


 
 
 

Question 17 of 40

What causes the crack-whip effect?


 
 
 

Question 18 of 40

You should not back a tractor under a trailer until the whole air system is:


 
 
 

Question 19 of 40

What should you do to prevent the crack-the-whip effect?


 
 
 

Question 20 of 40

What is the best way to prevent a rollover?


 
 
 

Question 21 of 40

What is off tracking?


 
 
 

Question 22 of 40

On the trailer air lines of a combination vehicle, the service line connects to the _____ on the trailer to control the pressure to the trailer brakes.


 
 
 

Question 23 of 40

What does the tractor protection valve do?


 
 
 

Question 24 of 40

When does the tractor protection valve close automatically?


 
 
 

Question 25 of 40

What are the two trailer air lines that every combination vehicle has?


 
 
 

Question 26 of 40

What is the purpose of the service line?


 
 
 

Question 27 of 40

What are the other names for the service line?


 
 
 

Question 28 of 40

What are glad hands?


 
 
 

Question 29 of 40

What is the emergency air line?


 
 
 

Question 30 of 40

What does the trailer hand valve do?


 
 
 

Question 31 of 40

How many times should you drain the air tanks?


 
 
 

Question 32 of 40

What is the first step to coupling tractor semi trailers?


 
 
 

Question 33 of 40

Which of the following is the best action you could take when the parking brakes don't release?


 
 
 

Question 34 of 40

What are trailer air tanks used for?


 
 
 

Question 35 of 40

What consideration should be made when you park a trailer that doesn't have spring brakes?


 
 
 

Question 36 of 40

Which shut-off valves should remain closed?


 
 
 

Question 37 of 40

When doing an inspection, which of the following would best describe a working landing gear?


 
 
 

Question 38 of 40

What is the second step to coupling tractor semi trailers?


 
 
 

Question 39 of 40

What happens if the trailer height is too high?


 
 
 

Question 40 of 40

What is the third step to coupling tractor semi trailers?


 
 
 


 
 
Rate the test

Want to share feedback about the CDL practice tests or our website? You can do so by leaving us a rating or by sending an email to marketing@roehl.net. We appreciate your experience on our site and may even want to feature it.

User Rating
Roehl CDL Practice Test
Rated 4.71/5 based on 100 ratings
5 star
78
4 star
17
3 star
4
2 star
0
1 star
1

Let's Connect

We make it easy for you. Simply fill out this form and we’ll connect & match you with the driving job that best fits your needs.

Quick Apply

We make it easy for you. Simply fill out this form and we'll connect & match your with the driving job that best fits your needs.