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General Knowledge CDL Practice Test Part C

CDL Test Practice Exams & CDL Training Materials

Taking the CDL test will be much easier after going through our practice CDL tests here online. This is the General Knowledge portion of the CDL written practice exam. These questions are very similar to the ones you'll find on the actual CDL written test you'll be taking to get your CDL license. Follow along with the test questions below and read through the explanations that follow each CDL test question to get some better insights into the CDL exam and the trucking industry itself.

1. What effects can wet brakes cause?

A. Brakes can be weak or grab.
B. Brakes to work better.
C. You foot can get tired.


Answer

A. Brakes can be weak or grab.

The key word here in the question is "can". In 15 years of driving I can't remember one time that water effected the brakes. Now it will effect how easily a tire will lock up and start sliding and skidding, but I've never known it to effect the actual brakes themselves. But if you get this question on your CDL test you know the answer they are looking for.

2. How can you avoid wet brake problems?

A. Speed up, shift to a higher gear.
B. Slow down, shift to a low gear, gently put on the brakes.
C. Apply the brakes harder and faster.


Answer

B. Slow down, shift to a low gear, gently put on the brakes.

That's right. In the rain you have to back it down a bit and be more gentle with your braking. Shifting to a lower gear will allow the engine to help slow you down, also. Be very, very careful using your Jake Brakes on wet roads. If used incorrectly they can cause your drive tires to lock up and start sliding. You have no directional control over a tire that is sliding.

3. You should let air out of hot tires so the pressure goes back to normal.

A. True
B. False


Answer

B. False

Hot tires will cool down on their own. Besides, if a tire got so hot from overbraking and hot road conditions, you really do not want to be putting your face near it! Just stay away from it. I have heard a couple of tires blow from overheating and let me tell you, it's like a bomb going off! It will rattle the windows of nearby buildings.

4. You can safely remove the radiator cap as long as the engine isn't overheated.

A. True
B. False


Answer

B. False

You should never remove the radiator cap unless the engine has cooled down completely. It can take several hours for an engine to cool enough to add water to it.

5. What factors determine your selection of "safe" speed when going down a long steep downgrade?

A. Size of vehicle, traffic conditions, curves in the road.
B. Conditions of brakes, radio bulletins and alertness of driver.
C. Total weight of the vehicle, length of the grade, steepness, road conditions, and weather.


Answer

C. Total weight of the vehicle, length of the grade, steepness, road conditions, and weather.

As you can see, there are a lot of factors which go into determining the proper speed of descent on a mountain. Let me say this, though - most of the time you will only get the chance to descend a mountain too fast once. I mean that in the worst possible way. Take your time and be incredibly cautious. Let the other trucks go as fast as they want. If you're not sure which gear to be in, you're much better off starting down the hill real slow. If you're going too fast and the brakes get hot it is very difficult to slow down enough to downshift without overheating the brakes in a big way. You don't want to be in that position. Start off real slow and take it from there.

6. Why should you be in the proper gear before starting down a hill?

A. Because gravity can cause the speed of your vehicle to increase.
B. Because you don't want to shift going down a hill.
C. Because the clutch works better up a hill.


Answer

A. Because gravity can cause the speed of your vehicle to increase.

Refer to the explanation I gave to the previous question.

7. Describe the proper braking technique when going down a long steep downgrade.

A. Apply the brake just hard enough to feel a definite slowdown.
B. When your speed has been reduced to around 5 mph below your "safe" speed, release the brake.
C. When your speed has increased to your "safe" speed. repeat A and B
D. All of the above.


Answer

D. All of the above.

Yap - keep the truck under control. Smooth, but somewhat firm braking enough to feel the truck slowing down a bit and never let the truck get rollin above what you consider the safe speed.

8. What is a hazard?

A. Any road condition or other road user that is a possible danger.
B. A flashing amber light.
C. A small animal.


Answer

A. Any road condition or other road user that is a possible danger.

I think they just put this in there to make sure you understand the definition of the word because they use it about a million times in the CDL manual.

9. Why make emergency plans when you see a hazard?

A. To have something to do while driving
B. In order to protect yourself and others.
C. To avoid getting a ticket.


Answer

B. In order to protect yourself and others.

Always try to plan for a way out if something were to happen in front of you. Don't wait until you see a hazard, but assume a hazard is always about to appear in front of you or along side of you and continuously scan for a way out. Keep plenty of following distance at all times also. This is one of the best ways to avoid accidents.

10. Stopping is not always the safest thing to do in an emergency?

A. True
B. False


Answer

A. True

Sometimes you won't have time to come to a complete stop in order to avoid a hazard - like a head-on collision or an animal running out into the roadway. Sometimes stopping would be an over-reaction to something and can cause someone to run into the back of you or cause an accident behind you. You have to be aware of the circumstances and always be aware of the vehicles around you.

11. What are some advantages of going right instead of left around an obstacle?

A. You can avoid a head on collision.
B. Taking the shoulder may be best.
C. Someone may be passing to the left.
D. All of the above.


Answer

D. All of the above.

Again, you must be aware of your circumstances and know the conditions and the vehicles around you. There is no one-size-fits-all answer to how to handle an emergency, but generally speaking, going to the right can be less dangerous than going to the left around something. It will totally depend upon the circumstances though.

12. What is an "escape ramp?"

A. Ramps that are located a few miles from the top of a downgrade to help you stop.
B. A quick way to get out of town.
C. Ramps to get on and off an interstate highway fast.


Answer

A. Ramps that are located a few miles from the top of a downgrade to help you stop.

Escape ramps are generally structured like normal off-ramps, but are usually built on an incline off the side of the highway and are made of a deep, soft gravel or sand that will stop a truck that has lost its brakes going down a mountain.

13. If a tire blows out you should put the brake on hard to stop quickly.

A. True
B. False


Answer

B. False

Often times, the only tires that will have much of an immediate effect on you if they blow out are the steer tires. But drive tires and trailer tires can blow out without causing any loss of control of the vehicle. In fact, it is not uncommon to drive for a while with a flat tire on your drives or your tandems and not even know it. So as long as it's not a steer tire, there is no need to panic. You can generally drive at a somewhat slower speed to the next tire shop to get it repaired or replaced. I drove for 15 years and have over 1.5 million miles and I've never blown a steer tire. It happens, but it's rare.

14. What are some things to do at an accident scene to prevent another accident?

A. Try to get your vehicle to the side of the road.
B. If you're stopping to help. park away from the accident.
C. Put on your flashers and set out reflector triangles.
D. All of the above.


Answer

D. All of the above

If you're involved in an accident, the last thing you want to do is make things worse. Stay calm and think. Don't panic and do something that causes more harm than good. Keep your truck a good ways away from an accident scene if you're stopping to help in order to allow emergency vehicles access to the scene.

15. Name two causes of tire fires:

A. Tight turns and gravel roads
B. Under inflated tires and duals that touch
C. Driver smoking and following too close


Answer

B. Under inflated tires and duals that touch

Although this is true, tire fires are pretty rare. In fact, I've seen a number of brake fires, but I don't know that I've ever seen a tire fire. Keep your tires properly inflated though. They will wear out much faster if you don't.

CDL Practice Tests

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