What is the sliding mechanism and locking device for tandem axles on trailers?

Tandem release arm / locking pins

Why can a damaged exhaust system be hazardous to you?

Poisonous fumes can enter the cab or sleeping compartment.

Excessive noise can damage your hearing.

The exhaust can pollute the environment.

You are checking your steering and exhaust systems during a pre-trip inspection. Which of these statements is true?

Excessive steering wheel play can make it hard to steer.

Leaks in the exhaust system are not a problem if they are outside of the cab.

Some leakage of power steering fluid is normal.

You are checking your steering and exhaust system during a pre-trip inspection. Which of these problems, if found, should be fixed before the vehicle is driven?

A small leak of power steering fluid

Steering wheel play of more than 10 degrees

As part of your vehicle inspection test, if your vehicle has a cargo lift, you will have to

explain the process of checking it for correct operation.

check it for any missing parts.

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20 questions
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California CDL: Pre-Trip Inspection Practice Test

20 pre-trip inspection questions for the California CDL Knowledge Test, out of 91 in the app. Answer each to see whether you got it right and why. The real California Pre-Trip Inspection test has 20 questions and you need 16 correct (80%) to pass.

Facts updated Oct 26, 2026
Official source: law.cornell.edu
Independent, not affiliated with the DMV. How we write our questions

How it works

1Pick an answer20 questions, one tap each.
2See the ruleRight or wrong, every answer is explained.
3Get your scoreCompared with the real 80% pass mark.

Start the test

0/20 answered0 correctPass mark 80%

1Question 1 of 20
What is the sliding mechanism and locking device for tandem axles on trailers?
Not quite. The answer is Tandem release arm / locking pins
If so equipped, make sure that the locking pins are locked in place and the release arm is secured.
2Question 2 of 20
_________ are the brackets, bolts, or bushings that are used to attach the spring or air bag to the axle and vehicle frame.
Not quite. The answer is Spring mounts
Spring mounts consist of the brackets, bolts, shackles, and bushings used for attaching springs or air bags (for an air ride suspension) to the vehicle frame. During your inspection, check that the spring mounts are secured to the vehicle's frame and axles. Check that no bushings are damaged or missing. Check that there are no broken, loose, or missing bolts or U-bolts.
3Question 3 of 20
Why can a damaged exhaust system be hazardous to you?
Not quite. The answer is Poisonous fumes can enter the cab or sleeping compartment.
The exhaust system is designed to help remove toxic gases produced by the engine. A leak in the exhaust system can allow poisonous carbon monoxide (CO) to seep into the cab or sleeping compartment. A buildup of CO is more likely in cold weather, when you may have the cab windows closed.
4Question 4 of 20
You pump the pedal three times and hold it down for five seconds, making sure that the pedal does not move. What are you inspecting?
Not quite. The answer is Hydraulic brakes
If your vehicle has hydraulic brakes, test them by pumping the brake pedal three times and then applying firm pressure to it for five seconds, making sure the pedal does not move during that time. If your vehicle has air brakes, test them by performing the final air brake check as described in the California Commercial Driver Handbook.
5Question 5 of 20
Which belt should you make sure is securely mounted and adjusts and latches properly?
Not quite. The answer is Safety / seat
You should wear your safety belt at all times while you're riding. (You may fail your skills test if you don't wear it.) Make sure it is in good condition and securely mounted in the cab. Also make sure it adjusts and latches properly.
6Question 6 of 20
Which of these is part of the steering system?
Not quite. The answer is Pitman arm
The Pitman arm is attached to the output shaft of the steering box. The Pitman arm changes the rotation of the output shaft into back-and-forth movement, which is used to turn the front wheels of the CMV. The torque arm (also known as a radius rod) and bearing plate are parts of a vehicle's suspension.
7Question 7 of 20
Which of the following dashboard light indicators should you test?
Not quite. The answer is Turn signals
There are five dash indicators that you should ensure are working correctly: the left turn signal, the right turn signal, the four-way emergency flashers, the high beams, and the indicator for the anti-lock braking system (if your vehicle is so equipped).
8Question 8 of 20
While you're performing the pre-trip inspection, where should the ignition key be?
Not quite. The answer is In your pocket
While you are performing the pre-trip inspection, you do not want someone (such as a co-driver) who is unaware of your location to start your vehicle and accidentally injure you. Make sure you have the ignition key with you as you perform the inspection.
9Question 9 of 20
Which of these is part of your vehicle's suspension?
Not quite. The answer is Neither of the above
The drag link and Pitman arm are two components of the steering system.
10Question 10 of 20
You are checking your steering and exhaust systems during a pre-trip inspection. Which of these statements is true?
Not quite. The answer is Excessive steering wheel play can make it hard to steer.
If there is more than 10 degrees of play in your steering wheel, it will be harder for you to tell which way your front wheels are pointed. Have the problem corrected before you drive the vehicle. Ten degrees is equivalent to about 1¾ inches at the rim of a 20-inch steering wheel. According to federal regulations, there must not be more than 2½ inches of play at the rim of a 20-inch steering wheel.
Source: 49 CFR 570.60
11Question 11 of 20
If the wheel has a sight glass, check that the oil level is adequate. Otherwise, look for leaks around the
Not quite. The answer is hub oil seals and axle seals.
As part of your pre-trip inspection of the wheels, check the axle seals and the hub oil/grease seals for leaks. Look for oil or grease on the wheels and any visible evidence of cracks or leaks. If the wheel has a sight glass, you can visually confirm that the oil level is adequate.
12Question 12 of 20
You are checking your steering and exhaust system during a pre-trip inspection. Which of these problems, if found, should be fixed before the vehicle is driven?
Not quite. The answer is Both of the above
Your steering system is critical to your safety, especially in an emergency. Excessive steering wheel play may make it difficult for you to know which way your front wheels are pointed. A leak of power steering fluid may eventually lead to power steering failure if left uncorrected.
13Question 13 of 20
_________ should be clean with no dirt, illegal stickers, obstructions, or damage.
Not quite. The answer is The windshield and mirrors
Windshields and mirrors should be clean and free of damage, illegal stickers, or obstructions that could impede visibility.
14Question 14 of 20
Which of the following can disengage the engine from the drivetrain?
Not quite. The answer is Clutch and gearshift
To ensure that your vehicle doesn't move once you start the engine, first depress the clutch (unless the vehicle has an automatic transmission) and put the gearshift in neutral (or Park for an automatic transmission). Once the engine has started, slowly release the clutch.
15Question 15 of 20
The angle between the pushrod and arm should be a little over 90 degrees when the brakes are released and not more than 90 degrees when the brakes are applied. This refers to the
Not quite. The answer is slack adjusters.
The slack adjuster connects to the pushrod. If the slack adjuster has too much slack, the brake can fail.
16Question 16 of 20
Which of the following emergency equipment is federally required in a commercial motor vehicle?
Not quite. The answer is Fire extinguisher
Federal regulations require CMVs to carry a properly rated fire extinguisher and warning devices for stopped vehicles. Spare electrical fuses are no longer federally required, although they are still recommended if the vehicle uses fuses. First-aid kits and wheel chocks may be required by some employers or states, but they are not federally required for all CMVs.
Source: 49 CFR 393.95
17Question 17 of 20
Which of the following do you NOT need to clean during a walk-around inspection?
Not quite. The answer is Tires
When you drive, you must be able to see and be seen by other road users. During your walk-around inspection, clean all lights, reflectors, and glass as you go along. Your vehicle's license plates must also be clean and well secured.
18Question 18 of 20
Steering wheel play should NOT exceed ____ degrees.
Not quite. The answer is 10
If there is more than 10 degrees of play in your steering wheel, your vehicle will be harder to steer. Have the problem corrected before you drive the vehicle. Ten degrees is equivalent to about 1¾ inches at the rim of a 20-inch steering wheel. According to federal regulations, there must not be more than 2½ inches of play at the rim of a 20-inch steering wheel.
Source: 49 CFR 570.60
19Question 19 of 20
As part of your vehicle inspection test, if your vehicle has a cargo lift, you will have to
Not quite. The answer is do all of the above.
As part of your vehicle inspection test, if your vehicle is equipped with a cargo lift, explain how to check it for correct operation. Check for leaking, damaged, or missing parts. Also check that the cargo lift is fully retracted and securely latched.
20Question 20 of 20
Which of these keeps your vehicle from rolling when it's parked?
Not quite. The answer is Parking brake
The parking brake keeps your vehicle from moving when it's parked. The mechanism is separate from the service brakes that you use in normal driving.

Questions people ask

Is this California CDL: Pre-Trip Inspection Practice Test like the real California CDL Knowledge Test?

The questions are written in the same style as the real test, from official sources, with an explanation for each answer. The real test has 20 questions; this free test has 20.

How many questions are on the California CDL Knowledge Test?

The General Knowledge test has 20 questions. Each class and endorsement adds its own test.

What score do you need to pass the California CDL Knowledge Test?

You need 16 out of 20 correct (80%).

How old do you have to be to take the California CDL Knowledge Test?

You can take it from age 18.

Where can I practice more questions?

The Driving Exam Prep app has the full question bank for your test, a step-by-step roadmap, a mistakes review and a readiness score against the real pass mark.

Official sources

Our questions are written from these official sources. Always study your official handbook too: rules change, and our practice questions may differ from your real test.

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What is the sliding mechanism and locking device for tandem axles on trailers?

_________ are the brackets, bolts, or bushings that are used to attach the spring or air bag to the axle and vehicle frame.

Why can a damaged exhaust system be hazardous to you?

You pump the pedal three times and hold it down for five seconds, making sure that the pedal does not move. What are you inspecting?

Which belt should you make sure is securely mounted and adjusts and latches properly?

Which of these is part of the steering system?

Which of the following dashboard light indicators should you test?

While you're performing the pre-trip inspection, where should the ignition key be?

Which of these is part of your vehicle's suspension?

You are checking your steering and exhaust systems during a pre-trip inspection. Which of these statements is true?

If the wheel has a sight glass, check that the oil level is adequate. Otherwise, look for leaks around the

You are checking your steering and exhaust system during a pre-trip inspection. Which of these problems, if found, should be fixed before the vehicle is driven?

_________ should be clean with no dirt, illegal stickers, obstructions, or damage.

Which of the following can disengage the engine from the drivetrain?

The angle between the pushrod and arm should be a little over 90 degrees when the brakes are released and not more than 90 degrees when the brakes are applied. This refers to the

Which of the following emergency equipment is federally required in a commercial motor vehicle?

Which of the following do you NOT need to clean during a walk-around inspection?

Steering wheel play should NOT exceed ____ degrees.

As part of your vehicle inspection test, if your vehicle has a cargo lift, you will have to

Which of these keeps your vehicle from rolling when it's parked?

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Questions people ask

Official sources

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