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

Select the true statement about emergency brakes:

they are required to be held on by a mechanical force

all of these answers are correct

they are required to be activated the loss of air pressure

they are required on all commercial vehicles

2 / 40

Which of the following three hazard classes should NOT be placed into a temperature-controlled trailer (one with a heater/air conditioner unit)?

Classes 1, 3, and 4

Classes 1, 4, and 51

Classes 1, 21, and 3

Classes 1, 3, and 6

3 / 40

Select the true statement about dual air brake systems:

they have a single set of air tanks and hoses

they are required to have two warning alarms

they require less time to build up air pressure

they have one set of controls for two air brake systems

4 / 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

none of the answers listed

open the shut off valve at the back of both trailers

close the shut off valves at the back of each trailer

5 / 40

This should have no illegal stickers, dirt, obstructions, or damage to the glass.

Mirrors and windshield

The headlights

The rearview mirror

None of the answers listed

6 / 40

When stopping for railroad tracks, you must stop no closer than how many feet before the nearest track?

7 / 40

When would a drive-wheel skid result in a jackknife when pulling doubles?

when the tractor spins around

when the trailer slides to the right into the shoulder

when the tractor brakes lock up

when the trailer pushes the towed vehicle sideways

8 / 40

When transporting explosives you may not park:

Within 300 feet of a tunnel.

Within 5 feet of the traveled part of the road.

All of these answers are correct.

Near an open fire.

9 / 40

What is the purpose of the supply pressure gauge?

to inform you if there is too little air in the tank

to inform you of how much air is in the tank

to inform you about how hot the air in the tank is

all of these answers are correct

10 / 40

The golden rule for school buses when approaching and crossing railroad tracks is:

Stop, look, and turn on the radio lights overhead.

Stop, go, and stop.

None of these answers are correct.

Stop, look, and listen.

11 / 40

How can you determine if your vehicle is equipped with ABS?

check for yellow abs malfunction lamps on the instrument panel

all of these answers are correct

check if your vehicle was manufactured after March 1, 1998 (they are required to have the panel light)

look for wheel speed sensor wires that are coming from the rear of your brakes

12 / 40

What is most likely to occur when the front wheels begin to skid?

A roll over will occur.

You will continue heading in a straight line and moving forward no matter what direction you turn the steering wheel.

The power of the surge will disconnect the tank from the truck.

All answers listed.

13 / 40

You should_____to make an emergency stop with air brakes when using the stab braking method.

apply a full hand valve until you stop and press firmly on the brake pedal

apply pressure to the brake pedal until the wheels lock and then stay off of the pedal for as long as the wheels are locked

apply a firm pressure to the brakes, release the brake pedal once the wheels lock and then apply pressure to the brakes onces the wheels start rolling again

rapidly and lightly pump the brake pedal

14 / 40

Carry-on baggage cannot be stored:

Under the seat.

Behind the seats.

In the aisles and stairwells.

On the seats.

15 / 40

How should the pintle hook be when backing a dolly under the second trailer?

in the unlatched position

in a halfway open position

removed from the dolly

in the latched position

16 / 40

A shipment described on the Hazardous Waste Manifest may only be delivered to another _______ carrier or treatment facility, who then signs the ______, giving you a copy which you must keep.

licensed, manifest

responsible, papers

trucking, uniform hazardous waste manifest

registered, uniform hazardous waste manifest

17 / 40

In the event of an accident you should remember to do the following EXCEPT:

move the victims out of the way immediately

protect the area

notify authorities

stop any bleeding and keep the victims warm

18 / 40

The Emergency Response Guide, ERG, can best be explained as _____.

none of these answers are correct

a guide explaining what materials can be hauled together in the same vehicle

a guidebook for firefighters, police, industry workers, truck drivers, dock workers, and shippers on how to protect themselves and the public from hazardous materials

a guide explaining what materials can be hauled together in the same vehicle and a guidebook for firefighters, police, and industry workers on how to protect themselves and the public from hazardous materials

19 / 40

When driving with multiple trailers, which one should be right behind the tractor?

the trailer with the heaviest load

the trailer longest in length

the trailers shortest in length

the trailer with the smallest road

20 / 40

How do you check the air compressor governor "cut in" and "cut out" pressures?

all of these answers are correct

decrease the tank pressure by stepping on and off the brake

monitor the air pressure gauge

run the engine at a fast idle

21 / 40

Select the reason as to why you should not use the trailer hand valve while driving.

it could cause the trailer to skid

the trailer brakes will not be evenly applied

it should not be used on dry roads due to road conditions

it releases too much air from the system

22 / 40

When inspecting your bus, you must make sure that:

Rider signaling devices are working.

All of these answers are correct.

Every handhold and railing is secure.

Emergency exit handles are secure.

23 / 40

Which of the following is NOT an appropriate reason to flash your braking lights?

to warn drivers behind you when you need to slow down

to warn vehicles approaching you from behind that you are driving slowly

to signal to tailgaters that they are too close to your vehicle

to alert drivers behind you that there are hazards ahead

24 / 40

Select the statement that best describes what the trailer air supply control does:

when pulled out it supplies the trailer with air and when pushed in it shuts off the air and puts on the trailer emergency brakes

when pushed in it supplies the trailer with air and when you pull it out it shuts off the air supply and puts on the trailer emergency brakes

when pushed in it supplies the tractor with air and when pulled out it supplies the trailer with air

when pushed it it supplies the trailer with air and when pulled out it supplies the tractor with air

25 / 40

Which of the following is a recommended procedure when unloading the students?

Put the transmission in neutral gear and put on the brakes.

Tell students to remain seated until they are told to exit.

Let the students begin moving to the front of the bus before it's fully stopped to maximize efficiency.

Position yourself outside of the bus in front of crossover mirror to supervise unloading.

26 / 40

When should you avoid using the parking brake?

while on an incline

whenever you park

when the brakes are hot

when the air pressure is low

27 / 40

By law, the warning lights must only be used when approaching a:

Stop to load or unload students.

Busy intersection.

Sharp turns.

Any stop the bus makes.

28 / 40

How much space should you see between the lower and upper fifth wheel when checking the coupling of a converter dolly?

1 to 1 1/2 inches

1/2 to 1 inch

it depends on how heavy the load is

none

29 / 40

Alcohol evaporators in some air brake systems help to:

cleans out oil from the air lines

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

it removes fuel from the air lines

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

30 / 40

The best way to go into a curve is to decrease your speed going into the curve and then ____going through it.

slightly accelerate

ride the brake

shift down 2 gears

none of the answers listed

31 / 40

____is the most common type of foundation brakes used by heavy vehicles.

S-Cam drum

Wedge drum

None of the answers listed

Rectangle brakes

32 / 40

Why is the proper adjustment and use of all mirrors so vital to the safe operation of the school bus?

In order to see if small vehicles are driving in the bus blind spots.

In order to observe the danger zones around the bus and look for the students, traffic, and other objects in this area.

In order to clear up blind spots around the bus.

In order to observe the danger zones around the bus.

33 / 40

Select how brakes work on long, steep downgrades:

they are a supplement to the braking effect of the engine

it is the main braking mechanism

it's the main braking mechanism with the engine braking system available for emergency situations

it does not do anything

34 / 40

The correct trailer height when coupling the rear trailer is:

slightly lower than the center of the fifth wheel

when the locking jaws are open around the kingpin

the kingpin is touching the fifth wheel

there is 5 inches of space between the lower and upper fifth wheel

35 / 40

You should never brake and should rely only steering inputs to avoid a crash while driving a tanker truck.

False

True

True, but only in ideal conditions

True, but only on downgrades

36 / 40

Placarded vehicles must carry which type of fire extinguisher?

C-D fire extinguisher

A-B fire extinguisher

B-C fire extinguisher

Hazmat extinguisher

37 / 40

Select the load of the trailer that will require the shorter distance to stop.

a half loaded trailer

a 1/3 loaded trailer

an empty trailer

a fully loaded trailer

38 / 40

The CDL manual indicates the last step on picking up students at the bus stop is as follows:

Make a final check to confirm all traffic stops before opening the bus door and signaling students to approach.

Open the service door just enough to activate the alternating red light when traffic is in a safe distance from the bus.

Activate the amber flashing caution lights to warn vehicles that the bus will stop to load passengers soon.

Place transmission in park or neutral and set parking brake.

39 / 40

Cargo tanks ____.

are large drums used to contain hazmat that is loaded on a trailer

are tanks that the military uses to transport hazardous materials

are large drums temporarily attached to a vehicle

are bulk packagings permanently attached to a vehicle

40 / 40

While driving at night, which lights should you use as often as you can?

high beams

emergency flashers

novelty lights

low beams

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