CDL Combination Test Questions and Answers 2023

CDL Combination Test Questions and Answers 2023: Our CDL combination vehicles practice test will help you to pass the tests for combination vehicles Endorsements written test (tractor-trailer, doubles, triples, straight truck and trailer). The Combination Test Questions and Answers is only to give you the minimum knowledge needed for a written test of combination vehicles.

Combination vehicles are usually heavier, longer, and require more driving skills than single commercial vehicles. This means that drivers of combination vehicles need more knowledge and skill than drivers of single vehicles. In this chapter, we talk about some important safety factors that apply specifically to combination vehicles.

CDL Combination Test Questions and Answers 2023

CDL Combination Test Questions and Answers

Test Name	CDL Practice Test 2023
Language	English
License	Endorsements Permit
Total Questions	30 sample questions
Test For	Commercial Driver License
Test Preparation	Combination vehicles Endorsements
Country	USA
Explanation	No

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CDL Combination Vehicles Test

1 / 30

Which of the following is the correct definition of offtracking?

A) When a vehicle is turning the corner, the rear wheels follow a different path than the front wheels.

B) When a vehicle is turning the corner, the front wheels lead the rear wheels around the turn.

C) When a vehicle is turning the corner, the front wheels and rear wheels follow the same path.

D) Keeping the front of the rig as close to the curb as possible to avoid entering other lanes.

2 / 30

When coupling, the fifth wheel jaws should close around the __________________ of the kingpin.

A) middle

B) shank

C) head

D) bottom

3 / 30

When lowering the landing gear of a loaded trailer,

A) lower the gear until it makes firm contact with ground.

B) urn the crank in high gear a few extra turns after the landing gear makes firm contact with ground.

C) lift the trailer off the fifth wheel.

D) turn the crank in low gear a few extra turns after the landing gear makes firm contact with ground.

4 / 30

What will happen if the service air line comes apart while you are driving a combination vehicle?

A) nothing at all is going to happen

B) the trailer’s air tank will exhaust through the open line

C) nothing is likely to happen until you put on your brakes

D) the emergency trailer brakes will come on

5 / 30

After the tractor has coupled with the semitrailer, in what position should you put the front trailer supports, or landing gear, before driving away?

A) Halfway up

B) On the ground

C) Fully raised with the crank handle safely secured

D) Partway up without the crank handle secured

6 / 30

Failure to keep the _________ lubricated could cause steering problems because of friction between tractor and trailer.

A) glad hands

B) air supply knob

C) fifth wheel plate

D) trailer protection valve

7 / 30

If the service and emergency air lines are crossed when hooking up an old trailer, what will happen?

A) Nothing will happen.

B) The trailer spring brake will release.

C) You will be able to drive away, but you won’t have trailer brakes.

D) Water and dirt will enter the air lines.

8 / 30

The “normal” position of the trailer air supply control is used for

A) pulling a trailer.

B) shutting the air off.

C) parking a trailer.

D) putting on the trailer emergency brake.

9 / 30

When parking trailers without spring brakes, use _________ to safely secure the vehicle.

A) wheel chocks

B) the emergency brakes

C) the parking brake

D) the trailer hand brake

10 / 30

In combination vehicles, the trailer service brake should be tested with the ________, but controlled in normal operation with the _________.

A) trailer air supply control; hand valve

B) hand valve; foot brake

C) foot brake; hand valve

D) trailer emergency valve; foot brake

11 / 30

Emergency lines on combination vehicles are often color coded to keep them from getting mixed up. The service lines are coded with the color __________, and the emergency lines are coded with the color __________ .

A) blue . . . yellow

B) red . . . blue

C) blue . . . red

D) red . . . black

12 / 30

You are coupling a tractor and semitrailer, and ready to back your trailer under a semi-trailer. When is the trailer at the right height?

A) When the trailer is raised high above the trailer as the tractor is backed under it

B) When the trailer is raised slightly by the tractor as the tractor is backed under it

C) When the tractor and semitrailer are even

D) When the kingpin is lower than the fifth wheel

13 / 30

The standard following distance behind other vehicles is at least

A) one second for each ten feet of vehicle length plus another second if going over 40 mph.

B) one second for each twenty feet of vehicle length.

C) two seconds for each ten feet of vehicle length.

D) two seconds for each ten feet of vehicle length plus one second if going over 40 mph.

14 / 30

Why should the trailer glad hands be locked together or attached to “dead end,” or dummy, couplers when not in use?

A) To keep air pressure normal

B) To keep dirt out of the lines

C) To keep the service and emergency glad hands from getting mixed up

D) To prevent air from escaping

15 / 30

To supply air to the trailer air tanks in a combination vehicle, you must

A) press the trailer hand brake.

B) open the relay valve.

C) push in the trailer supply control.

D) pull out the trailer air supply control.

16 / 30

When should the trailer hand valve be used?

A) To test the trailer brake

B) To park the trailer

C) Only in an emergency

D) To drive the trailer

17 / 30

The air leakage rate for a combination vehicle (engine off, brake off) should be less than _________ psi per minute

A) 4

B) 1

C) 3

D) 2

18 / 30

When coupling a tractor and semitrailer, you must lock the kingpin into the fifth wheel. Which is the best way to check the connection?

A) Lock the trailer brakes and pull the tractor gently forward.

B) Drive forward.

C) Lock the trailer brakes and pull the tractor quickly forward.

D) Back up and unlock the trailer brake.

19 / 30

Fully loaded rigs are __________ times more likely to rollover in a crash than empty rigs

A) 8

B) 5

C) 10

D) 20

20 / 30

When coupling a tractor to a semitrailer, what should you hook up before backing under the trailer?

A) The emergency and service air lines

B) Nothing; you are ready to back up

C) The trailer air supply control

D) The tractor protection valve

21 / 30

When coupling with a semitrailer, back the tractor up

A) directly in front of the trailer.

B) in front of the right wheel.

C) at an angle to the trailer.

D) slightly off the center of the trailer.

22 / 30

Which of the following is a coupling device used to connect the service and emergency air lines from the truck or tractor to the trailer?

A) The trailer air supply control

B) The relay valve

C) Glad hands

D) The tractor protection valve

23 / 30

What are the two purposes of the emergency air line on combination vehicles?

A) To control the emergency brakes and carry air controlled by the foot brake

B) To supply air to the trailer air tanks and to connect the trailer air tank to the trailer air brakes

C) To carry air, which is controlled by the foot brake only

D) To supply air to the trailer air tanks and control the emergency brakes

24 / 30

Which of the following may happen if the tractor protection valve doesn’t work right?

A) Nothing will happen.

B) An air hose or trailer brake lead could drain all the air from the trailer and possibly cause a loss of control in the vehicle.

C) The engine may shut off.

D) The pressure may rise in the trailer.

25 / 30

Which of the following reduces the risk of rollover?

A) None of the above

B) Changing lanes quickly

C) Keeping the cargo as close to the ground as possible

D) Loading the cargo on one side of the truck only

26 / 30

The earliest and best way to recognize that your trailer has started to skid is by

A) periodically applying the brakes to check for traction.

B) carefully watching how other drivers are reacting to your vehicle.

C) seeing it in your mirrors.

D) feeling the rig “pull” to the right or left.

27 / 30

The tractor protection valve will close automatically if air pressure is low or in the range of

A) 20-45 psi

B) 46 psi or above

C) 0-10 psi

D) 11-19 psi

28 / 30

Your trailer has begun to skid. You should

A) use the trailer hand brake to straighten out the rig.

B) release the foot brake to get traction back.

C) turn hard in the direction of the skid.

D) apply the foot brake hard, and come to a full stop.

29 / 30

When the wheels of a trailer lock up and the trailer begins to swing around ______ is likely to occur.

A) offtracking

B) a rear wheel braking skid

C) rollover

D) trailer jackknife

30 / 30

How much space should be between the upper and lower fifth wheel after coupling?

A) More than 1 foot

B) 6 inches

C) 1 foot

D) No space

Your score is

The average score is 79%

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