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

What does outage mean?

It is the movement of the liquid.

It is how quickly the tanks drain.

It is the weight of the liquid.

It is the allowance needed for the expansion of liquid.

2 / 40

The school bus driver may be the only contact person from school system some parents meet. The percentage of such parents is as high as:

0.5

0.72

0.85

0.65

3 / 40

Suspension systems:

keep the axles in place

keep the load secure

keep the brake drums from failing

keep the steering wheel tight

4 / 40

How should you know when to shift?

every 3 to 5 seconds or engine speed

road speed and wind speed

engine speed and the shift indicator light

engine speed and road speed

5 / 40

If you have to swerve to avoid a hazard, it's important to:

Warn passengers with a loud and clear voice.

Know where other vehicles are around your bus by checking your mirrors.

None of these answers are correct.

Make sure your passengers are wearing seat belts.

6 / 40

How often should air tanks be drained?

every 6 hours

once a day

every 7 days

every 4-5 days

7 / 40

Which of the following should you do when confronted by an aggressive driver?

all of these answers are correct

if you can safely do it, call the police from a cell phone

avoid eye contact

ignore rude gestures and refuse to react negatively

8 / 40

What is a technical name?

The name for a hazardous material most commonly used on the street.

The name for a hazardous material used in scientific journals and texts, recognized as its chemical and microbiological name.

The name for a hazardous material most commonly used in the trucking community, accepted as standard.

The medical term for hazardous materials used by medical personnel.

9 / 40

The driver's manual advises you to disconnect the steering axle brake to keep the rig straight:

whever you feel like it

never

in ideal conditions

when it is raining

10 / 40

You should____to check the free play of manual slack adjusters on S-Cam brakes.

after parking on a slight grade, release the parking brake, activate the service brakes and check for vehicle movements

chock the wheels and release the parking brakes after parking on a level ground

drain off air pressure before adjusting after parking on level ground

apply the parking brake after stopping on level ground

11 / 40

Which trailer is most likely to tip over due to the crack the whip effect?

the last trailer of a double

the first trailer of a triples

the heaviest trailer

the last trailer of a triple

12 / 40

Why should you test the tractor protection valve?

to avoid the emergency brakes kicking on due to loss of air

all answers listed

to avoid loss of air from the trailer brakes

to avoid loss of air from the air hose

13 / 40

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

when accelerating it releases air

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

it prevents the brakes from failing

it is connected to the generator

14 / 40

Which of the following should you NOT do if you experience a tire failure?

stay off the brake pedal

you need to be aware that a tire has failed

engage the brakes hard and immediately

hold the steering wheel firmly

15 / 40

Air tanks should be drained:

to prevent sludge from clogginng up the brake system valves

at the end of each shift or day

manually when the automatic devices fail

all of these answers are correct

16 / 40

Buses may carry small-arms ammunition labeled ORM-D, emergency hospital supplies, and drugs. However, buses must never carry:

More than 500 pounds total of allowed hazardous materials, and no more than 100 pounds of any one class.

More than 750 pounds total of allowed hazardous materials, and no more than 100 pounds of any one class.

More than 250 pounds total of all allowed hazardous materials.

More than 1000 pounds total of allowed hazardous materials, and no more than 200 pounds of any one class.

17 / 40

You should_____when an emergency requires you to quickly stop your tanker.

turn off the abs and brace for impact

use stab or controlled braking

keep a firm pressure on the brake pedal

use the emergency brakes only

18 / 40

A trailer is at the right height to have the tractor backed up to it when:

it'll raise slightly when the tractor is backed up under it

the kingpin is about 1 1/5 inches above the fifth wheel

the top of the kingpin is even with the bottom of the fifth wheel

the fifth wheel will not come in contact with the kingpin

19 / 40

Why are you required to take an exam about air brakes?

you cannot receive a CDL at all otherwise

it is a federal requirement

all trucks have air brakes

you would have to get a CDL with a restriction otherwise

20 / 40

What are the dividers that are inside tankers that have an opening at the bottom and top?

Bulkmets

Baffles

Taffles

Layers

21 / 40

You downshift automatic transmissions ______.

none of these answers are correct

at the bottom of a hill

before going down a hill

half way down a hill

22 / 40

Which of the following statements about downshifting is NOT true?

downshift before starting down a hill

downshift before entering a curve

downshift before climbing a hill

downshift when you get to the bottom of a hill

23 / 40

Class A explosives must not be transported in a combination vehicle if the vehicle includes:

Two or more trailers.

None of these answers are correct.

A 200 inch wheelbase trailer.

A placarded cargo tank.

24 / 40

On tandem axle for trailers, the sliding mechanism and locking device is:

Tandem release (locking pin/arm)

Fifth wheel

Metal frame

Air brake system

25 / 40

Two causes of tire fires are ______.

under-inflated tires and duals that touch

hot brakes and under-inflated tires

under-inflated tires and poor retreads

duals that touch and road debris

26 / 40

When stopped on a divided highway where should your reflectors be placed?

10 feet, 100 feet, and 200 feet toward the approaching traffic

20 feet, 150 feet, and 300 feet toward the approaching traffic

30 feet, 100 feet, and 150 feet toward the approaching traffic

15 feet, 75 feet, and 150 feet toward the approaching traffic

27 / 40

Anti-lock brakes:

Are not available in mosst busses.

Lengthen stopping distance.

Keep your wheels from locking during hard brake application.

Work only when you activate in-cab switch.

28 / 40

Select the true statement in regards to large combination vehicles taking longer to stop.

they take longer to stop when loaded down

they take the same amount of time to stop when empty or loaded

they take longer to stop than bobtail tractors

they take longer to stop when they are empty

29 / 40

It is important for driving safety to always be looking ahead. Which of the following is NOT a recommended time/distance that you should be looking ahead?

about 5 car lengths on the highway

about 1/4 mile for open highway driving

about 1 block for city driving

about 12-15 seconds

30 / 40

Your vehicle is going down a long hill and your brakes begin to fail. What should you do?

downshift

pump the brake pedal

put the gears in neutral

look for an escape ramp or an escape route

31 / 40

Buses are prohibited from carrying all of the following hazardous materials except:

Small-arms ammunition.

Properly secured tear gas canisters.

Materials labeled radioactive in the space occupied by people.

Properly labeled poison gas canisters.

32 / 40

A driver that hauls hazardous materials must attend training every:

3 years

None of these answers are correct

2 years

1 year

33 / 40

When should air tanks be drained?

at every restroom break stop

they don't need to be drained

every 7 days

at the end of each working day

34 / 40

Why should you know the outage?

Liquids expand different amounts.

Heavier liquids don't require outage.

Just in case you become a contestant in a trivia competition.

Baffles are not always permitted with certain types of liquids.

35 / 40

Mirrors with a convex surface or "spot" mirrors _____.

make things look farther away and smaller than they actually are

are illegal in most states

they show a larger area than flat mirrors so do not need to be checked as often

make things look closer and larger than they actually are

36 / 40

Select the statement that best explains the "crack-the-whip" effect.

it is when you make a sudden movement of the steering wheel or a quick lane change and the rear trailer tends to swing out. The force of the rear trailer becomes amplified, which will cause it to roll over (rearward amplification).

it is when the trailer is half full with the cargo loaded in the front half of the trailer. When you make a sudden movement of your steering wheel the cargo will forcefully slide towards the back of the trailer which will force the trailer to roll over.

it is when you make a sudden movement of the steering wheel or a quick lane change and the tractor tends to rock and sway. The velocity of the rearmost trailer forces the tractor to roll over before the trailer.

it is when the trailer is half full with the cargo loaded in the rear half of the trailer. When you make a sudden movement of your steering wheel the cargo will forcefully slide towards the back of the trailer which will force the trailer to roll over.

37 / 40

Which of the following are some suspension system defects?

cracked or broken spring hangers

broken leaves in leaf spring

all of these answers are correct

leaking shock absorbers

38 / 40

What will occur if you cross the connect the air lines?

the tractor brakes will lock up

the tractor will not be able to move

there will not be air going to the trailer brakes

nothing will occur, it'll funciton as normal

39 / 40

Spring brakes are usually held back by_____during normal driving.

pressure of the spring

air pressure

heat

clamps

40 / 40

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

the lines are hotter

none of the answers listed

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

longer reaction time

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