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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 Iowa doubles triples test consists of 20 questions. To pass, you must correctly answer at least 16 questions (80%). The IA CDL doubles triples test covers the following sections of the Iowa CDL Manual: Driving Safely, Air Brakes (if you plan to operate vehicles equipped with air brakes), Combination Vehicles, Doubles and Triples. Take this IA CDL practice test now to prepare for the actual test!
1. No matter how small the cargo is, it should have at least:
1 tie-down.
4 tie-downs.
2 tie-downs.
2. Before driving a vehicle with a dual brake brake system, the driver should:
wait at least 10 minutes before driving.
pump the brake pedal 10 times to build pressure.
allow time for the air compressor to build up a minimum of 100 psi pressure in both the primary and secondary systems.
3. To prevent rollover, you should:
drive in the left lane.
drive on the shoulder of the road when possible.
drive slowly around corners.
4. If the low air pressure warning light comes on, you should:
continue to drive normally.
stop immediately.
call for help.
5. When you see you will need to slow down, you can warn drivers behind you by:
turning on the right turn signal.
slamming on the brakes.
tapping the brakes a few times.
6. When parked on the side of the road, you should:
flash your brake lights.
turn off all lights.
use the 4-way emergency flashers.
7. Rough acceleration can cause:
tire damage.
damage electrical and brake lines.
mechanical damage.
8. Dual tires:
should come in contact with each other whenever possible.
should always come in contact with each other.
should not come in contact with each other.
9. If a load is 50 feet long, the minimum number of tie-downs required is:
10. Many large vehicles have convex (curved, "spot, "fisheye") mirrors. Convex mirrors:
misrepresent reality by showing a larger area than flat mirrors.
are illegal in most states.
make things look smaller and farther away than they really are.
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IA Doubles Triples CDL Test

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