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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 Indiana doubles triples test consists of 20 questions. To pass, you must correctly answer at least 16 questions (80%). The IN CDL doubles triples test covers the following sections of the Indiana CDL Manual: Driving Safely, Air Brakes (if you plan to operate vehicles equipped with air brakes), Combination Vehicles, Doubles and Triples. Take this IN CDL practice test now to prepare for the actual test! Important: Triple trailers are not legal in Indiana.
1. The trolley valve should be used only:
to test the trailer brakes.
to prevent skids.
in an emergency.
in driving.
2. Most heavy-duty vehicles use:
hydraulic brakes.
solid brakes.
air brakes.
pressure brakes.
3. If your ABS fails:
the first step is to get the vehicle off the road and stop.
your tires might grab unexpectedly and you could lose control.
you will still have normal brake functions.
you will have no brake function, and could lose control.
4. If during vehicle inspection a tire is too hot to touch, you should:
remain stopped until the tire cools off.
immediately decrease air pressure.
make sure there is enough engine oil on the tires.
let air out.
5. When going down a steep downgrade, you should primarily brake using:
the parking brake.
the braking effect of the engine.
the service brakes.
the emergency brake.
6. If your vehicle is equipped with air brakes, loss of air pressure in the emergency line will cause:
the springs to put on the brakes.
the trailer supply valve to open.
the trailer emergency brakes to come on.
the vehicle to slide back and forth.
7. Rough acceleration can cause:
mechanical damage.
damage electrical and brake lines.
tire damage.
All of the above.
8. The service line is also called:
cable line.
brake line.
power line.
control line.
9. When the wheels of a trailer lock up:
the vehicle will gradually come to a complete stop.
ABS will increase stopping power.
the trailer will tend to swing around.
All of the above.
10. Which of the following statements about drivers fixing an engine or changing a tire is true?
They must park within 5 feet of the roadway.
They usually pay attention to the danger roadway traffic is to them.
They often do not pay attention to roadway traffic.
Roadway traffic is not a danger to them.
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IN Doubles Triples CDL Test

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