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Safely pulling double and triple trailers requires knowledge and skill. If you want to pull double or triple trailers, you must add the Doubles/Triples (T) endorsement to your Class A CDL. The Illinois doubles triples test consists of 20 questions. To pass, you must correctly answer at least 16 questions (80%). The IL CDL doubles triples test covers the following sections of the Illinois CDL Manual: Driving Safely, Air Brakes (if you plan to operate vehicles equipped with air brakes), Combination Vehicles, Doubles and Triples. Take this IL CDL practice test now to prepare for the actual test!
1. The trolley valve should be used only:
in an emergency.
to prevent skids.
in driving.
to test the trailer brakes.
2. Texting while operating a commercial motor vehicle is:
only allowed at night.
acceptable if you are contacting your dispacther.
acceptable if you are contacting your supervisor.
3. Strong winds can make it difficult to stay in your lane, especially when:
going into tunnels.
driving alongside other vehicles.
driving at speeds below 40 mph.
coming out of tunnels.
4. Which of the following is not a braking system on a truck?
Parking brake
Steering brake
Emergency brake
Service brake
5. To prevent getting sleepy while driving, you should:
close the vent.
keep cool by opening the window.
keep the cab warm.
drive alone whenever possible.
6. Overloading a vehicle with cargo can have negative effects on all of the following except:
Weight limits
Speed control
7. The tractor protection valve:
prevents the trailer from being accidentally released.
keeps air in the brake system should the trailer develop a bad leak.
keeps your wheels from locking up when you brake hard.
keeps air from going out if the air compressor develops a leak.
8. Your vehicle has hydraulic brakes. When you press the brake pedal while driving and the pedal goes to the floor, remember that:
shifting into neutral may help slow the vehicle.
pumping the brake pedal may generate enough hydraulic pressure to stop the vehicle.
the parking brake should never used to slow the vehicle.
All of the above.
9. Headache racks:
protect you from being hit by your cargo.
help you keep weights within legal limits.
can blind other drivers.
None of the above.
10. Your mirrors should be adjusted so that:
a part of the vehicle is visible in the mirror.
no part of the vehicle is visible in the mirror.
the rear of the vehicle is visible in the mirror.
more than half of the mirror shows the vehicle.
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IL CDL Doubles Test

Number of questions: 20
Correct answers to pass:16
Passing score:80%
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