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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. If your trailer starts to skid, you should:
release the brakes.
steer in the opposite direction.
lock the brakes.
pump the brakes.
2. What should you do if you doubt you have safe space to pass under a low bridge?
Increase the weight of your vehicle to clearing under the bridge.
Go slowly, and take another route if you are not sure you can make it.
Assume that the height posted at the bridges is correct.
If no warnings are posted, assume there is enough clearance under the bridge and proceed slowly.
3. The tractor protection valve:
supplies air to the trailer air tanks.
controls the emergency brakes on combination vehicles.
keeps air in the tractor brake system should the trailer break away or develop a bad leak.
works the trailer brakes.
4. You should be especially alert for drunk drivers:
in the morning.
late at night.
around shopping areas.
in the early evening.
5. How can you tell if a converter dollie has ABS?
There is an ABS plaque on the right side of the dolly.
There is an ABS system on the right side of the dolly.
There is a red lamp on the left side of the dolly.
There is a yellow lamp on the left side of the dolly.
6. Rims with welding repairs:
are acceptable only when carrying a heavy load.
can be used for tires in the front of the vehicle.
can be used for tires in the rear of the vehicle.
are not safe.
7. If your trucks has a high center of gravity, which of the following is true for curves?
You should travel at the posted speed limit.
You should slow down, as your truck can roll over at the posted speed limit for the curve.
Reduce your speed to a crawl.
None of the above.
8. When driving trucks with trailers, drivers should:
make quick lane changes.
avoid making sudden movements with the steering wheel.
decrease their following distance.
push the brake pedal to the floor when braking.
9. If an item placed on a flatbed trailer is 7 feet long, it should have __ tie-downs.
10. By pushing the trailer air supply control knob in, you:
supply the trailer with air.
shut the air off and put on the trailer emergency brakes.
keeps air in the tractor or truck brake system.
supply the tires with air.
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IL CDL Doubles Triples Test

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