CDL doubles and triples practice test

A: T. The Double and Triple Trailers endorsement is T; Class A drivers must add it and pass a special knowledge test to pull doubles or triples. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 1.1 Commercial Driver License Tests (Endorsements), page 1-2.

C: They are less stable, and more things can go wrong. Doubles and triples are less stable than other commercial vehicles, and there are more things that can go wrong. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.1 Pulling Double/Triple Trailers, page 7-1.

D: It may be too fast. A safe speed on a curve for a straight truck or single-trailer combination may be too fast for a set of doubles or triples. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.1.1 Prevent Trailer from Rolling Over, page 7-1.

A: Steer gently and go slowly. Take corners, ramps and curves slowly and with gentle steering to keep the trailers upright. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.1.1 Prevent Trailer from Rolling Over, page 7-1.

D: They are longer and can't be turned or stopped suddenly. Besides their length, doubles and triples can't stop or turn quickly, so they need extra room: more following distance and bigger gaps in traffic. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.1.5 Manage Space, page 7-1.

C: Don't get into a spot you cannot pull straight through. Make sure you do not get into a spot you cannot pull straight through; know how lots are arranged to avoid a long and difficult escape. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.1.7 Parking the Vehicle, page 7-1.

B: Seeing it in your mirrors. The earliest and best way to recognize a trailer skid is by seeing it in your mirrors; check them any time you brake hard. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 6.1.5 Prevent Trailer Skids, page 6-2.

D: The rear wheels of the last trailer. The longer the rig, the more it off-tracks, and with two or more trailers the last trailer's rear wheels cut in the most. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 6.1.6 Turn Wide, page 6-3.

B: Class A drivers who wish to pull double or triple trailers. The manual says the endorsement is added to the licenses of Class A drivers who wish to pull double or triple trailers. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 1.1 Commercial Driver License Tests (Endorsements), page 1-2.

B: Because of the crack-the-whip effect. Doubles and triples are more likely to turn over because of the crack-the-whip effect, so you must steer gently. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.1.2 Beware of the Crack-the-whip Effect, page 7-1.

B: So you can slow down or change lanes gradually when needed. Multiple trailers must be handled very smoothly to avoid a rollover or jackknife. Looking well ahead gives you time to slow or change lanes gradually. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.1.4 Look Far Ahead, page 7-1.

A: Allow more following distance and make sure gaps are large enough before entering or crossing traffic. Allow more following distance, make sure gaps are large enough before entering or crossing traffic, and be certain you are clear at the sides before changing lanes. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.1.5 Manage Space, page 7-1.

C: Release the brakes to get traction back. Stop using the brake to get traction back. Don't use the trailer hand brake to straighten out the rig, because the trailer brakes caused the skid in the first place. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 6.1.5 Prevent Trailer Skids, page 6-3.

A: As you complete the turn, keeping the rear close to the curb. Turn wide as you complete the turn rather than swinging wide to the left before starting, which keeps other drivers from passing you on the right. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 6.1.6 Turn Wide, page 6-3.

C: The last trailer. The last trailer in a combination is the most likely to turn over. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.1.2 Beware of the Crack-the-whip Effect, page 7-1.

D: March 1, 1998. ABS is required on converter dollies built on or after March 1, 1998 (49 CFR 393.55). Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.1.8 Antilock Braking Systems on Converter Dollies, page 7-1.

A: At least 1 second for each 10 feet of vehicle length, plus another second. Follow far enough behind: at least 1 second for each 10 feet of vehicle length, plus another second if going over 40 mph. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 6.1.2 Steer Gently, page 6-1.

D: Rearward amplification. Rearward amplification causes the crack-the-whip effect, which can turn the trailer over in a quick lane change. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 6.1.2 Steer Gently, page 6-1.

A: It has a yellow lamp on the left side of the dolly. A converter dolly that is required to have ABS carries a yellow lamp on its left side. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.1.8 Antilock Braking Systems on Converter Dollies, page 7-1.

A: The rear trailer is twice as likely to turn over as the tractor. On the rearward amplification chart, 2.0 means the rear trailer is twice as likely as the tractor to tip over. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 6.1.2 Steer Gently, page 6-1.

B: In the first position, right behind the tractor. The more heavily loaded semitrailer should be in the first position behind the tractor, with the lighter trailer in the rear. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.2.1 Coupling Twin Trailers, page 7-1.

C: 3.5. Triples have a rearward amplification of 3.5, meaning you can roll the last trailer 3.5 times as easily as a five-axle tractor. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 6.1.2 Steer Gently, page 6-1.

C: A coupling device of one or two axles and a fifth wheel used to couple a semitrailer to the rear of a tractor-trailer. A converter dolly is one or two axles with a fifth wheel. It lets a second semitrailer hook onto the back of a tractor-trailer to make a double. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.2.1 Coupling Twin Trailers, page 7-2.

B: They have greater length and more dead axles to pull with the drive axles. Your drive axles have to pull a longer rig with more unpowered (dead) axles than other drivers do, which raises the chance of skids and lost traction. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.1.6 Adverse Conditions, page 7-1.

D: Connect the emergency line, charge the trailer air tank, then disconnect the emergency line to set the trailer emergency brakes. Hook up the emergency line long enough to charge the trailer tank, then disconnect it. That sets the trailer emergency brakes, provided the slack adjusters are right. If in doubt, chock the wheels. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.2.1 Coupling Twin Trailers, page 7-1.