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Doubles and Triples CDL Practice Test

CDL Test Practice Exams & CDL Training Materials

Taking the CDL test will be much easier after going through our practice CDL tests here online. This is the doubles and triples portion of the CDL written practice exam. These questions are very similar to the ones you'll find on the actual CDL written test you'll be taking to get your CDL license. Follow along with the test questions below and read through the explanations that follow each CDL test question to get some better insights into the CDL exam and the trucking industry itself.

1. Is it important to be careful when driving doubles and triples?

A. Yes
B. No


Answer

A. Yes

Double and triple trailers are very difficult to stop on slick road surfaces and it's more difficult to maintain lane control with them because the rear trailer tends to "wag" like a dog's tail.

2. Special care should be taken when pulling two or three trailers because more things can go wrong and are less stable than other commercial vehicles.

A. True
B. False


Answer

A. True

You have more connections, more parts that can brake, they tend to tip over easier - especially the rear trailer, they are more difficult to stop on slick roads, and the move around more like a dog's tail wagging.

3. Doubles and triples are not as likely to turn over as are other combination vehicles.

A. True
B. False


Answer

B. False

Doubles and triples will flip over easier if you use more harsher steering inputs because it tends to make the rear trailer "wag" like a dog's tail or "whip" around a corner.

4. Is it alright not to check all the critical parts when doing a pretrip inspection on doubles or triples?

A. Yes
B. No


Answer

B. No

Of course you must check all critical parts on all truck before driving them.

5. When driving doubles or triples how whould they be driven to avoid rollover or jackknifing?

A. Fast
B. Smoothly
C. Slowly


Answer

B. Smoothly

You want to use real gentle steering inputs so that the back trailer doesn't whip around in the turns or "wag" like a dog's tail while driving down the road.

6. Do doubles and triples need more space on the highway than other commercial vehicles?

A. Yes
B. No


Answer

A. Yes

Doubles and triples are not only longer, but also need more space on the road because they can’t be turned or stopped suddenly. While driving them, allow more following distance and make sure you have large enough gaps before entering or crossing traffic.

7. For the safest handling on the road when pulling doubles and triples how should the load be positioned?

A. The lighter load in first position, the heavier in the rear.
B. The heavier load in first position, the lighter in the rear.
C. It does not matter which trailer is heavier.


Answer

B. The heavier load in first position, the lighter in the rear.

If you put the heavier trailier in the rear position, it will want to whip from side to side and the truck will become very unstable.

8. What is a converter dolly used for?

A. To couple tow or three trailers behind a tractor truck.
B. To help move cargo in a semi-trailer.
C. To couple a trailer to a tractor.


Answer

A. To couple and tow or three trailers behind a tractor.

The converter dolly is basically a single tandem axle with a fifth wheel on it that couples two trailers together.

9. Do all converter dollies have spring brakes?

A. Yes
B. No


Answer

B. No

Many converter dollies do not have spring brakes because they have to be pushed around by hand and there is no way to release the spring brakes without air pressure to the chamber. A dolly parking brake control was later developed but not required.

10. All of these methods can be used to secure a second trailer before coupling, except:

A. Make sure the trailer spring brakes are locked
B. Back another trailer to the rear of the trailer you want to hook to which will act as a brace and keep the trailer from rolling
C. Chock the wheels
D. If the second trailer does not have spring brakes, drive the tractor close to the trailer, connect the emergency line, charge the trailer air tank, and disconnect the emergency line


Answer

B. Back another trailer to the rear of the trailer you want to hook to which will act as a brace and keep the trailer from rolling

You never want to push one trailer up against another one to secure it from rolling. It might work, but it would likely cause damage to the trailers.

11. The dolly tow bar may fly up if you unlock the pintle hook with the converter dolly still under the rear trailer.

A. True
B. False


Answer

A. True

Yeah, and not only can the tow bar fly up into the air, but it can take your teeth out at the same time! You must be careful and think clearly when dealing with hooking and unhooking doubles and triples.

12. You should use different methods for uncoupling second and third trailers.

A. True
B. False


Answer

B. False

The technique is the same whether it is the second or third trailer you are dealing with.

13. Coupling and uncoupling methods are the same for most common tractor-trailer combinations, but there are other ways of coupling and uncoupling the many types of truck-trailer combinations that are in use.

A. True
B. False


Answer

A. True

Most modern trucks have been standardized and it is unlikely you will come across much variance. However, there is always the chance that you will come across a system you've never dealt with before. If you're not sure of the procedures, always find out the proper method of handling things before attempting to do so.

14. There are more things to inspect on a combination vehicle than on a single vehicle.

A. True
B. False


Answer

A. True

There are a lot more parts and connections involved with doubles and triples than there are with a standard single trailer.

15. A safe speed on a curve for a straight truck or a single trailer combination vehicle is always the same as for a set of doubles or triples.

A. True
B. False


Answer

B. False

At times, the safe cornering speed for a set of doubles and triples may be much lower than the safe cornering speed for a single trailer commercial vehicle.

CDL Practice Tests

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