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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 Oregon doubles triples test consists of 20 questions. To pass, you must correctly answer at least 16 questions (80%). The OR CDL doubles triples test covers the following sections of the Oregon CDL Manual: Driving Safely, Air Brakes (if you plan to operate vehicles equipped with air brakes), Combination Vehicles, Doubles and Triples. Take this OR CDL practice test now to prepare for the actual test! Important: Triple trailers are not legal in Oregon.
1. With a dual air brake system:
each system shares air tanks.
each system shares the same lines and hoses.
each system has its own air tanks, hoses and lines.
one system is the main braking system while the other is a back-up system.
2. Emergency lines are often coded with the color ___ to keep from getting them mixed up with the service line.
3. After an accident, an improper use of flares could cause:
the springs to put on the brakes.
a fire if spilled fuel is on the ground.
air pressure to build from 50 to 100 psi within 2 minutes.
the vehicle to slide back and forth.
4. When backing a trailer, you should turn the steering wheel to the right to make the trailer go left (or vice versa). Once the trailer starts to turn, you should:
turn the wheel the other way to follow the trailer.
keep backing up.
turn the wheel more  in the direction you want to go.
None of the above.
5. You are driving a double. Before entering traffic, you should:
always come to a complete stop.
turn on your headlights.
make sure you have a large enough gap before entering or crossing traffic.
assume there is enough room to merge into traffic.
6. If you unlock the pintle hook with the dolly still under the rear trailer:
the brakes could be damaged by the combined forces of the springs and the air pressure.
your vehicle might roll away.
the dolly tow bar may fly up.
steam and boiling water can spray under pressure.
7. The center of gravity of a trailer should be:
as low as possible.
at the front of the trailer.
as high as possible.
at the rear of the trailer.
8. Alcohol:
improves muscle coordination.
improves reaction time.
impairs depth perception.
does not affect judgement.
9. The last trailer of triples is ______ as likely to turn over as a five-axle tractor.
4 times
3.5 times
5 times
10. Your vehicle should be equipped with all of the following except:
Instructions on how to perform a vehicle inspection test
Fire extinguisher
Spare electrical fuses
Warning devices for parked vehicles
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OR 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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