iowa
CDL Practice Test

Below are practice questions for the Iowa CDL test. The site is free and you are able to take the practice test as many times as you need to as you prepare to obtain your Iowa CDL. The questions and answers covered in these Iowa practice CDL tests are taken from the Iowa DOT CDL manual. You will be presented with 40 questions and you must answer 34 questions correctly to pass. There is a 50-minute time limit. You may not go back once you answer a question. Click the "Start Test
" button below to begin.

1 / 40

On a bus, you may sometimes haul small-arms ammunition, emergency shipments of drugs, or hospital supplies. The total weight of all such hazardous materials must not be greater than:

500 pounds

250 pounds

300 pounds

100 pounds

2 / 40

You should___when driving down a long steep hill.

repeatedly pump the brake pedal

release the brake once the vehicle is traveling 5 mph below the safe speed

use the engine brakes only

begin braking once the vehicle is 10 mph above safe speed

3 / 40

A tank trailer should never be fully loaded due to:

The movement is stronger.

The will be more shifting of the load.

The liquid can expand causing a leak from the trailer.

The baffles aren't as effective.

4 / 40

This object releases the fifth wheel locking jaw to allow uncoupling.

The arm bar

The release arm

The locking pins

The apron

5 / 40

How should the hand valve be used?

to test the trailer brakes

when the trailer is fully loaded down

only in emergency situations

only in conjuction with the foot brake

6 / 40

What are the three types of emergency equipment that you must have with your vehicle?

warning devices for parked vehicles, first aid kit, flares

fire extinguisher, spare electrical fuses, warning devices for parked vehicles

none of these answers are correct

first aid kit, fire extinguisher, flares

7 / 40

Alcohol evaporators in some air brake systems help to:

decrease the chances of ice in the air brake valves in cold weather

cleans out oil from the air lines

it removes fuel from the air lines

decreases the risk of water in the air brake valves in cold weather

8 / 40

Select the statement that is not part of the air-brake system:

service brake system

emergency brake system

clutch brake system

parking brake system

9 / 40

When does your vehicle's single brake system need an adjustment?

if the compressor cuts out at between 70 and 90 psi

when the governor stops between 75-90 psi

when the pressure builds from 85 to 100 psi in less than 1 minute

if the pressure builds from 50 to 75 psi in less than 3 minutes

10 / 40

The act of operating a motor vehicle in a selfish, bold, or pushy manner, without regard for the rights or safety of others is known as.

aggressive driving

defensive driving

road rage

distracted driving

11 / 40

What is the best way to see the sides and rear of your vehicle?

all of these answers are correct

your mirrors

rear view cameras

a helper

12 / 40

Which of the following factors is NOT used to determine your safe speed when going down a long steep downgrade?

total weight of the vehicle and cargo

length and steepness of grade

time of day

weather

13 / 40

Play of the steering wheel should not exceed:

5 degrees

10 degrees

30 degrees

15 degrees

14 / 40

Select the true statement about convex ("spot") mirrors.

they make things look farther away and smaller than they actually are

they are against the law in the majority of states

you do not need to look at them as often as flat mirrors

they make things closer and larger than they really are

15 / 40

Which of these statements about speed management and braking is true?

You need about four times as much stopping distance at 40 mph as at 20 mph.

Stopping time increases by one second for each 10 mph over 20 mph.

The posted speed limit will always allow you to stop safely.

The total stopping distance of a bus is the distance it takes to stop once the brakes are applied.

16 / 40

_____ create a little above 90 degree angle between the adjuster arm and push rod when the brakes are released and no less than 90 degrees when the brakes are applied.

brake disc

slack adjusters

air lines

brake drums

17 / 40

Check to ensure that____when inspecting the coupling.

the electrical cable is unplugged

there is minimal slack in the air lines

there is no slack at all in the air lines

the landing gear handle is free to hang down

18 / 40

Drivers who transport route controlled radioactive materials must carry a dated certificate of radioactive materials training. This training must have ocurred within the last:

1 years

4 years

3 years

2 years

19 / 40

Select the true statement in regards to an application pressure gauge:

it is connected to the generator

it shows how much air pressure you are applying to the brakes

when accelerating it releases air

it prevents the brakes from failing

20 / 40

This object should not move more than an inch by pulled by hand with the brakes released for manual slack adjusters.

The brake chambers

The brake pushrod

The bounce absorbers

The air lines

21 / 40

The safety valve is usually set to open at:

125 psi

225 psi

75 psi

150 psi

22 / 40

You downshift automatic transmissions ______.

half way down a hill

before going down a hill

at the bottom of a hill

none of these answers are correct

23 / 40

Why do air brakes take longer to stop than hydraulic brakes?

it takes more time for the air to flow through the lines

none of the answers listed

the lines are hotter

longer reaction time

24 / 40

The purpose for the emergency air line is:

none of the answers listed

supply air to the trailer air tanks and on combination vehicles, controls the service brakes

to supply air to the trailer air tanks and, on combination vehicles, controls the emergency brakes

supply air to the tractor air tanks and on combination vehicles controls the emergency brakes

25 / 40

Select the statement that best describes what the service line is for.

it is controlled by the foot brake or trailer hand brake and carries air

it is controlled by the trailer hand brake and carries air

it is controlled by the foot brake and carries air

all answers listed

26 / 40

What keeps air in the tanks should the air compressor develop a leak?

the tractor relay valve

the air compressor

the engine protection valve

the one-way check vavle

27 / 40

You should keep a minimum of ____between another vehicle and the double trailer with 100 ft truck driving at 30 mph.

8 seconds

13 seconds

15 seconds

10 seconds

28 / 40

This item should be firmly attached the to frame, be solid, and clear of objects:

The lock pins

None of these answers are correct answers are correct

The locking jaw

The catwalk

29 / 40

Where are the two main places where the hazardous material identification number appears?

On the package and on paperwork at the shipping point of origin.

On the shipping papers and on the package.

On the package and on paperwork at the shipping destination.

On the shipping papers and on a secret document in the driver's wallet.

30 / 40

The manual says you should look _____ ahead while driving.

15 to 20 seconds, at highway speeds, about a half of a mile

5 to 8 seconds, at highway speeds, about an eighth of a mile

12 to 15 seconds, at highway speeds, about a quarter of a mile

9 to 12 seconds, at highway speeds, about a quarter of a mile

31 / 40

Select the best description of a baffle tank:

They are tanks divided down into multiple smaller tanks.

They are divided and have holes for liquid to flow through controlling surge.

It is one large tank.

None of the answers listed.

32 / 40

You need to raise the landing gear just to the height of where it clears the pavement before driving.

false

true

only in ideal conditions

only in raining conditions

33 / 40

What school bus accidents should be reported?

No accidents.

All accidents.

Only accidents determined to be the fault of the bus driver.

Only accidents casusing injury.

34 / 40

Which trailer should be the first one after the tractor?

the trailer that is the shortest in length

none of the answers listed

the trailer that weighs the least

the trailer that weighs the most

35 / 40

The front trailer supports should be____before driving away.

raised fully and the crank handle secured in its bracket

3 turns down from the top and the crank handle secured in its bracket

raised 1/2 way with the crank handle secured in its bracket

raised 1/3 of the way with the crank handle secured in its bracket

36 / 40

When driving tank vehicles you should:

Maintain the posted speed limit as you enter the curve.

Decrease your speed before entering a curve and then accelerate through it.

None of the answers listed.

Come to a stop before entering a curve and then accelerate through it.

37 / 40

Select the situation in which you should use the hand valve to park a combination vehicle.

when parking at loading docks

in no situation

during the winter

when parking on a grade

38 / 40

What does the amount of liquid you can carry depend on?

The center of gravity.

The vehicle's horsepower rating.

The material the baffles are made from.

The outage of the liquid.

39 / 40

Air brake systems should not lose air faster than____when testing for air leakage rates in combination vehicles before applying the brake pedal.

3 psi a minute

6 psi a minute

2 psi a minute

5 psi a minute

40 / 40

What do you need to do to supply air to the air tanks of the second trailer?

open up the shutt off valves on the rear of the first trailer and close the shut off valve at the back of the second trailer

open the shut off valve at the back of both trailers

none of the answers listed

close the shut off valves at the back of each trailer

Your score is

The average score is 0%

5/5 - (1 vote)

CDL Category Practice Tests

CDL Practice Test

How To Get An iowa Commercial Drivers License

Individuals may apply for their CDL starting at age 18. To be eligible for interstate driving as well as HazMat and Doubles/Triples applicants must be 21 years of age or older. All individuals applying for an Iown CDL must present a Medical Examiner’s Certificate according to the United States Federal Regulations.

If any one of the descriptions below is true about an applicant, they will be disqualified from receiving their CDL.

Driver posses more than one driver’s license.
Driver was convicted of driving under the influence in the past 24 months.
Driver has a suspended, denied, canceled, or revoked driver’s license.

Endorsements
H – Hazardous Materials
N – Tank Vehicle
T – Doubles/Triples
X – Hazmat and Tank Comb
P – Passenger Vehicle
S – School Bus

Drivers must take a knowledge test as well as a practical skills test to showcase their knowledge of commercial driving laws and their ability to operate a commercial vehicle.

Hit the Open Road

iowa CDL License Test Tips

Applicants must complete a general knowledge test to display their understanding of commercial driving laws. The general knowledge exam is comprised of 50 questions. Those seeking a Class A CDL will need to complete an additional 20 question test on combination vehicles. Applicants seeking additional endorsements will need to take an additional test on the endorsement topic. The Passenger, Tank, and Doubles/Triples Endorsements are 20 question tests. Removing the Air Brake Restriction, the Iowa Operator and School Bus Endorsements are 25 questions. The Hazmat Endorsement is a 30 question test. All applicants must pass the respective assessments with a score of 80 percent or better to receive their Iowa CDL permit.

A skills assessment is required of all applicants. This assessment is comprised of three parts, which are the pre-trip inspection, basic controls skills, and on-road driving. Individuals applying for their P and S endorsements will be required to take the skills test in the respective vehicle for their endorsement.

Additional Information

Information on the Iowa Department of Transportation

The Iowa Department of Transportation administers CDL requirements and testing in Iowa. To get more information contact them via:

Website: https://iowadot.gov/DriversVehicles#CommercialDrivers

Phone: 515.239.1101

Additional Iowa CDL Helpful Links

Please use the links below to access more valuable Iowa CDL testing resources and to learn more about practice driving tests for the state of Iowa.

iowa CDL Practice Test

CDL Category Practice Tests

CDL Practice Test

How To Get An iowa Commercial Drivers License

Hit the Open Road

iowa CDL License Test Tips

Additional Information

Information on the Iowa Department of Transportation

Additional Iowa CDL Helpful Links

iowa
CDL Practice Test