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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 Oklahoma doubles triples test consists of 20 questions. To pass, you must correctly answer at least 16 questions (80%). The OK CDL doubles triples test covers the following sections of the Oklahoma CDL Manual: Driving Safely, Air Brakes (if you plan to operate vehicles equipped with air brakes), Combination Vehicles, Doubles and Triples. Take this OK CDL practice test now to prepare for the actual test! Important: Triple trailers are not legal in Oklahoma.
1. Radial and bias-ply tires:
should be used together.
should not be used together.
should be used together only when driving in packed snow.
2. As part of your vehicle inspection, you are checking that air flows to all trailers. After using the trailer handbrake to provide air to the service line, you go to the rear of the rig. When you open the emergency line shut-off valve at the rear of the last trailer, you should hear:
the service line valve close.
a mechanical vibration.
air escaping from the open valve.
3. As you approach off ramps and on ramps, remember:
that the posted speed limit may not be safe for larger vehicles.
to always brake and turn at the same time.
that downgrades make it easier to reduce speed.
4. Because of the "crack-the-whip" effect, doubles and triples:
are more likely to run out of gas than other combination vehicles.
are much slower than other combination vehicles.
are more likely to turn over than other combination vehicles.
5. What is true about tire chains?
You should watch the official video tutorial by the manifacturer before putting them on.
You must carry the at least 6 chains and extra cross-links.
You should learn how to put the chains on before you need to do it in snow.
6. When coupling double trailers, if the second trailer does not have spring brakes, to set the trailer emergency brakes you should:
1. Connect the emergency line 2. Drive the tractor close to the trailer 3. Disconnect the emergency line 4. Charge the trailer air tank.
1. Drive the tractor close to the trailer 2. Connect the emergency line 3. Charge the trailer air tank 4. Disconnect the emergency line.
1. Disconnect the emergency line 2. Drive the tractor close to the trailer 3. Charge the trailer air tank 4. Connect the emergency line.
7. If your vehicle is equipped with air brakes, loss of air pressure in the emergency line will cause:
the trailer emergency brakes to come on.
the springs to put on the brakes.
the vehicle to slide back and forth.
8. When driving in heavy traffic, the safest speed is:
faster than the other vehicles.
slower than the other vehicles.
the same speed as the other vehicles.
9. Dollies with ABS are required to have a malfunction lamp:
on the rear.
on the right side.
on the left side.
10. Rough acceleration can cause:
tire damage.
damage electrical and brake lines.
mechanical damage.
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Doubles Triples OK 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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