CDL General Knowledge Practice Test Part A

Taking the CDL test will be much easier after going through our practice CDL tests here online. This is part A of 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.

* Question 1. When preparing to do a pre-trip inspection you must check to see that the parking brakes are on and/or chocked.

A. True
B. False

* Answer: A. True

Anytime you are going to get out of the truck, or anytime you will be near the truck in general, you want to make sure the parking brake is on.

* Question 2. When getting in to start the engine and inspect inside the cab you must

A. Make sure the parking brake is on.
B. Put gearshift in neutral (or park if automatic).
C. Start engine and listen for unusual noises.
D. All of the above.

* Answer: D. All of the above.

This stuff will be important for your pre-trip inspection, also. Always check the parking brake first. In most tractor trailers the engine can only be started with the shifter in neutral.

* Question 3. Look at the gauges - the oil pressure gauge should come up to normal within how long after starting the engine?

A. Minutes
B. Seconds
C. It does not matter.

* Answer: B. Seconds

It does take a few seconds for the engine to build oil pressure, but not more than that. If you start the engine and the oil pressure doesn't come up within maybe 10 seconds, something is wrong and you should shut the engine down immediately.

* Question 4. You should check the following for looseness, sticking, damage or improper settings:

A. Steering wheel
B. Accelerator, brake and clutch pedals
C. Transmission controls
D. All of the above

* Answer: D. All of the above.

This stuff will be important for the pre-trip inspection portion of your CDL test, also. Always make sure that all of the controls seem to be operating properly before driving.

* Question 5. After inspecting mirrors and windshields for cracks, dirt, illegal stickers, or other obstructions to your vision, you should:

A. Look in the mirror to see if you look good.
B. Clean and adjust as necessary.
C. Not worry about any of it.

* Answer: B. Clean and adjust as necessary.

Always make sure your mirrors are adjusted properly before you start driving. It is quite annoying, and can be quite dangerous, to begin driving and then discover that your mirrors are not adjusted properly. Your instructor will look for this on the pre-trip inspection portion of your CDL test.

* Question 6. When checking lights you should:

A. Make sure that the parking brake is set.
B. Turn off the engine and take the key with you.
C. Turn on the headlights and four way flashers.
D. All of the above.

* Answer: D. All of the above.

This stuff will be important for the pre-trip inspection portion of your CDL test, also. Again, always check the parking brake first. If you turn on the headlights and four way flashers you'll be able to check all of the lights except the brake lights. I used to check the brake lights at night. You can usually tell if they're coming on if you're in a fairly dark area of a parking lot, or if you're backed up against something like a dock or a wall.

* Question 7. What should wheel bearing seals be checked for?

A. Color of paint used on cover
B. Cleanliness
C. Hub oil level and no leaks

* Answer: C. Hub oil level and no leaks

Often times on a tractor trailer if the wheel bearing seals are leaking you will find a lot of hug oil either laying in the rim or covering the rim. You may also find a lot of dry, black residue on the rim. This is often times from the brake shoes. If you see a lot of it one on rim as compared with the other rims it could be a sign that the brake is adjusted too tightly and the shoe is dragging hard. It may sometimes do this on a wheel whose brake shoes are new, also. A lot of dry, black residue on a rim is usually a warning sign, though that something is wrong.

* Question 8. How many red reflective triangles should you carry?

A. 1
B. 2
C. 3
D. 4

* Answer: C. 3

Not only should you know this for the pre-trip inspection portion of your CDL test, but if you get inspected by the DOT out on the road they will almost always look for triangles and a fire extinguisher. It's one of the easiest things to check for and an easy ticket if they're looking to write one.

* Question 9. How do you test hydraulic brakes for leaks?

A. Pump the brake pedal three times, then apply firm pressure to the pedal and hold for five seconds. The pedal should not move.
B. Drive 20 mph and slam on the brakes.
C. Drive slowly and pump the brake pedal. Make sure it doesn't hit the floor.

* Answer: A. Pump the brake pedal three times, then apply firm pressure to the pedal and hold for five seconds. The pedal should not move.

This stuff will be important for your pre-trip inspection portion of your cdl test, also. You will likely not have a vehicle with hydraulic brakes present for your CDL test, but the CDL examiner may ask you this question to see if you know it, so be prepared. This technique does not apply at all to air brakes.

* Question 10. Why put the starter switch key in your pocket during the pre-trip inspection?

A. So you don't lose it
B. So no one moves the vehicle
C. For your safety

* Answer: C. For your safety

Now if you're at a truckstop, I'd say the answer is "So some crazy nut-case doesn't run off with my truck!" But for the purpose of your CDL exam, it's for your safety.

* Question 11. To avoid roll backs when you start, you should:

A. Stop on a flat area
B. Engage the clutch very quickly
C. Press the accelerator
D. Partly engage the clutch before you take your right foot off the brake

* Answer: D. Partly engage the clutch before you take your right foot off the brake

This stuff will be important for the driving portion of your CDL test, also. In a car, you generally have to give it a good amount of gas as you're letting out on the clutch. In a tractor trailer, this usually isn't the case. A diesel engine has so much torque that if you're starting off in the correct gear you should be able to slowly let out on the clutch without touching the accelerator pedal and the truck will begin rolling.

If you let the truck roll backwards during the driving portion of your CDL test, it is considered an automatic failure. They consider it one of the biggest mistakes you can make.

* Question 12. What is the proper way to hold the steering wheel?

A. Firmly with both hands on opposite sides of the wheel
B. With your right hand on the wheel
C. Firmly with one hand at the top of the wheel and the other at the bottom

* Answer: A. Firmly with both hands on opposite sides of the wheel

If you thought the answer was "in your mouth", then you're my type of driver! Anyhow, you've heard the ole' "10 and 2" - just do it like they say - firmly with both hands on opposite sides of the wheel. Make sure you do this for your CDL test, also.

* Question 13. Why should you back toward the driver's side?

A. Backing roward the right side is dangerous
B. So you can see better
C. A and B

* Answer: C. Both A and B

If you weren't sure about this one, then you haven't tried backing up a truck yet. You can not see well at all when you are backing toward the passenger side. They call it "blind-side backing" or "blind-siding" because you really are pretty much blind coming in from the passenger side. "Blind-siding" is something you will always try to avoid, but it's a necessary evil sometimes.

* Question 14. When backing, why is it important to use a helper?

A. It makes people think you are a better driver.
B. There are blind spots you can't see.
C. It's more fun when you have help.

* Answer: B. There are blind spots you can't see.

In real life it's pretty rare to have someone helping you. However you will find yourself backing into some really tight places next to other trucks and it's good to have someone looking out for your blind spots in those occasions. But don't count on it.

Patience is the most important thing when it comes to safety. If you're backing into a tight spot, make sure you stop and get out to look at your blind spots. Backing into somebody's mirrors or into the side of a building because you were assuming you were ok is just really dumb. Stop, get out, and look. I drove for 15 years and I was as good as anyone on the road when it came to backing, and I used to get out and look on a regular basis. Not only is it safe, but other drivers will respect you for that. They know you're smart and patient - and that combination makes for a good, safe driver.

* Question 15. What is the most important hand signal that you and the helper should agree on?

A. Stop
B. Go
C. Right
D. Left

* Answer: A. Stop

Listen, this really is important. Everybody has different ideas when it comes to hand signals. It doesn't matter what signals you are using, as long as you both agree on what they are. I used to like to use a closed fist to mean stop. It's easy to distinguish from everything else. Waving, holding an open hand, and all of the other common ones were too hard to distinguish from other signals.

Generally speaking, your helper will not be "steering" you. You may ask someone to watch your blind spot and let you know if you're getting too close. If they put up the "stop" signal, then you know you're too close to something and you know what you have to do to get corrected. So you don't really need someone "steering" you. You just need to know if you're going to hit something.

* Question 16. What are two special conditions where you should downshift?

A. When starting off fast and speed shifting
B. Before starting down a hill and before entering a curve
C. Before starting up a hill and before entering a curve

* Answer: B. Before starting down a hill and before entering a curve

The key word here is "before". Do not downshift when you're going around a curve - it's very dangerous. Be very careful with braking, also. You want to be at the correct speed and in the correct gear before you get to the curve or the hill.

If you find yourself coming up on your exit too fast, please do not attempt to take the exit and assume you'll get slowed down. Go on to the next exit and get turned around. Everybody - myself included - has this happen from time to time. It's no big deal. Play it safe - do not enter a curve - especially an exit ramp - too fast.

* Question 17. When should you downshift automatic transmissions?

A. When going down grades
B. When going up grades
C. when going around curves
D. None of the above

* Answer: A. When going down grades

I'm not going to get too technical when it comes to automatic transmissions, which I have been driving for the past 5 years, but I will say again that you would like to be in the correct gear and at the correct speed before you start down a hill if possible. Often times you'll start down a hill and realize you're a gear too high. No problem - correct it right away. The longer you wait, the hotter your brakes are going to get. Get in the proper as soon as you possibly can.

* Question 18. Retarders keep you from skidding where the road is slippery.

A. True
B. False

* Answer: B. False

Retarders, or "engine brakes", or "Jake Brakes" as they are commonly known, are very dangerous to use on slippery roads and in tight curves. Using Jake Brakes is a similar effect to only applying the brakes to your drive tires. Jake Brakes do not apply any stopping force to your steer tires or your trailer tandems, and you must be aware of this. If you use them on real slippery roads or in tight curves they can cause your drive tires to lock up for a moment, losing traction, and causing your truck to jacknife. Jake Brakes are an amazing safety device but are only to be used in certain circumstances. Please get more information and advice from your driving instructors at your truck driving school.

* Question 19. What are the two ways to know when to shift?

A. Use engine speed (rpm) and road signs
B. Use your watch and engine sound
C. Use engine speed (rpm) and use road speed (mph)

* Answer: C. Use engine speed (rpm) and use road speed (mph)

You must match up a certain engine speed with a certain road speed to be in the proper gear. Consult the mechanics at the company you work for to find out the proper RPM range for the engine you have in your truck. All engines are a little bit different. Before long you'll get a feel for the engine in your truck and where it seems to make power and where it seems to go flat.

* Question 20. How far ahead should you look?

A. Most good drivers look 20 to 30 seconds ahead
B. Most good drivers look 5 to 10 seconds ahead
C. Most good drivers look 2 to 4 seconds ahead
D. Most good drivers look 12 to 15 seconds ahead

* Answer: D. Most good drivers look 12 to 15 seconds ahead

You will always be scanning as your driving along. Scan way ahead, scan the traffic immediately in front of you, and scan your mirrors. Always knowing the traffic and road conditions around you from moment to moment is called having a "good awareness". You must know you're situation at all times - who's around you and what the road conditions are.

What many people don't realize is that scanning further down the road will actually improve your lane control. If you look at the roadway very close to the front of your truck, you tend to steer too much and you weave a bit more than you should. Scan ahead and your peripheral vision will keep you in your lane better. This was something my trainer taught me my very first day on the road - and he was right.

Obviously it is much safer to scan 12-15 seconds ahead of the vehicle to avoid oncoming situations.