Nebraska CDL: Double & Triple Trailers Practice Test

Not quite. The answer is Allow a greater following distance than for smaller commercial vehicles.

Doubles and triples need more space because they can’t be turned or stopped suddenly. Allow a greater following distance behind the vehicle in front of you.

Not quite. The answer is The rig may jackknife.

Check your mirrors to monitor your trailers and see if a trailer has begun to skid. Do this every time you have to brake hard. Once the wheels of a trailer begin to skid, the risk of jackknifing is high. Once the trailer swings out of your lane completely, you may not be able to prevent a jackknife.

Not quite. The answer is open the shut-off valves at the rear of the first trailer and close the shut-off valves at the rear of the second trailer.

Air must travel through the air lines of the tractor and all trailers – and that's all. Open the shut-off valves at the rear of each trailer but the last one to enable the air to travel to the trailer behind it. Close the shut-off valves at the rear of the last trailer to keep air from escaping.

Not quite. The answer is A sudden movement with the steering wheel can result in a tipped-over rear trailer.

Because of rearward amplification (the "crack-the-whip" effect), the rearmost trailer is much more prone to rolling over. Avoid sudden steering changes that could cause the rearmost trailer to roll over.

Not quite. The answer is do both of the above.

In bad weather or mountain driving or on slippery roads, use extreme caution. When you drive a double or triple, you're pulling a lot of dead axles with just a few drive axles. This increases the chance of loss of traction, causing a skid. Also, rearward amplification makes the rearmost trailer much more prone to rolling over. Drive slowly around curves and turns and avoid sudden moves.

Not quite. The answer is Use wheel chocks.

If the second trailer doesn’t have spring brakes, drive the tractor close to the trailer, connect the emergency line, charge the trailer air tank, and disconnect the emergency line. This will set the trailer emergency brakes (assuming the slack adjusters are correctly adjusted). However, if you have any doubt about the effectiveness of the trailer's braking system, chock the wheels.

Not quite. The answer is Lower the second semitrailer's landing gear.

When uncoupling a set of standard doubles, the first unit to be uncoupled is the second semitrailer. To do this, lower its landing gear just enough to take some weight off the dolly. Then close the air shut-off valves on the first semitrailer and on the dolly (if so equipped). Disconnect the dolly's air and electrical lines from the second semitrailer. Release the dolly's fifth wheel latch, and pull the tractor forward so it pulls the dolly out from under the second semitrailer. After this is done, start to uncouple the dolly from the first semitrailer. These steps include lowering the dolly's landing gear and unhooking the dolly from the first semitrailer's pintle latch.

Not quite. The answer is a yellow lamp on the left side.

A converter dolly with antilock brakes is required to have a yellow ABS lamp on its left side. All converter dollies built since March 1, 1998 have antilock brakes.

Not quite. The answer is Doubles/triples flip over from quick steering movements more easily than do many other vehicles.

Because of rearward amplification (the "crack-the-whip" effect), steering changes affect the rearmost trailer much more than they affect the front trailer or the tractor. Avoid quick or sharp steering changes that could cause the rearmost trailer to roll over.

Not quite. The answer is only the more common types of combinations.

The official CDL manual's section on double and triple trailers usually describes how to couple and uncouple the more common types of double and triple combinations. However, there are other ways of coupling and uncoupling the many types of truck-trailer and tractor-trailer combinations that are in use. To learn how to couple and uncouple the vehicles you will be driving, consult the manufacturer's or owner's specifications.

Not quite. The answer is B.

If you swing wide to the left before you turn right, another vehicle may try to pass you on your right while you are turning. Instead, as shown in path B, make the right turn with the rear of your vehicle as close to the curb as possible and turn wide as you complete the turn. This will deny other vehicles enough room on the right to try to pass you.

Not quite. The answer is less

Double and triple vehicles are more prone to rolling over or jackknifing than single vehicles are. Avoid sudden braking or steering changes. Look far enough ahead that you can slow down or change lanes gradually when necessary.

Not quite. The answer is Rocky Mountain double

A double pup trailer consists of two 28.5-foot trailers, known as "pup trailers." A double pup trailer is also known as an STAA trailer, named for the Surface Transportation Assistance Act (STAA). This standard-double configuration is the only type of double trailer that is allowed nationwide. A Rocky Mountain double trailer consists of a 40- to 53-foot trailer followed by a 28.5-foot pup trailer. Rocky Mountain doubles are allowed in certain Western states. A turnpike double trailer consists of two 48-foot trailers. Turnpike doubles can be found traveling on expressways in the Eastern states.

Not quite. The answer is using the dolly's parking brake control.

To connect the converter dolly to the first semitrailer, release the dolly's brakes so it can be moved. You release the dolly's brakes by opening the air tank petcock (valve) or using the dolly's parking brake control if the dolly is equipped with spring brakes.

Not quite. The answer is the shut-off valves, the converter dolly or dollies, and the air brakes on all trailers.

To inspect a double or triple, first inspect it just as you would inspect any combination vehicle. Then check that the shut-off valves are open on all trailers but the last trailer. Check each converter dolly to be sure that the pintle hook is properly latched.

Not quite. The answer is sometimes lack antilock brakes.

All trailers and converter dollies built since March 1, 1998 are required to have antilock brakes (ABS).

Not quite. The answer is Check for normal air pressure. Release the parking brakes. Pull forward slowly. Apply the trailer brakes, using the hand control if so equipped.

Checking your trailer's service brakes is a four-step process: 1. Check for normal air pressure. 2. Release the parking brakes. 3. Pull your vehicle forward slowly. 4. Apply the trailer brakes, using the hand control (trolley valve) if so equipped. If the trailer brakes are properly connected and working, you should feel them come on at this point.

Not quite. The answer is slightly raised.

To test the coupling of the dolly to the second trailer, you'll pull the tractor forward so the dolly will pull against the kingpin of the second trailer. Before doing so, raise the trailer's landing gear slightly. This will prevent damage if the trailer moves, and prevent the trailer from falling onto the ground if the dolly pulls away from the trailer.

Not quite. The answer is latched.

When coupling a converter dolly to the trailer in front of it, place the dolly's pintle eye on the trailer's pintle hook. Latch the pintle hook closed. Secure the dolly's safety chains to the trailer.

Not quite. The answer is 5

In this context, articulation or pivoting means movement between two units separated by a joint, such as between a tractor and a trailer. A triple combination has 3 semitrailers connected with 2 converter dollies. This combination has 5 points of articulation: (1) the fifth wheel of the tractor; (2) the pintle hook of the first trailer; (3) the fifth wheel of the first converter dolly; (4) the pintle hook of the second trailer; and (5) the fifth wheel of the second converter dolly.