Wisconsin CDL: Double & Triple Trailers Practice Test

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 pull against the pin of the second trailer.

Test the coupling by pulling against the pin of the second semitrailer.

Not quite. The answer is fifth; one or two

A semitrailer can be connected to a converter dolly because, like the rear of a typical tractor, it has a fifth wheel and one or two axles.

Not quite. The answer is Either (a) or (b)

Federal regulation 49 CFR 380.205 states that you must meet various requirements before you can start training to operate a triple long combination vehicle. These requirements include 6 months' immediately prior experience driving either a tractor/semi-trailer combination or a tractor/semi-trailer/trailer combination, with a gross combination weight rating (GCWR) of at least 26,001 pounds.

Not quite. The answer is Hook the converter dolly to the front semitrailer.

To couple standard doubles, the first step is to correctly position the dolly in front of the second semitrailer. You can do this by hand or by picking up the dolly with the first semitrailer. Either way, the dolly must be connected to the first semitrailer before proceeding further. Once this is done, back the tractor, first semitrailer, and dolly until you back the dolly underneath the second semitrailer. Only after you've checked and tested the coupling, and connected all the air lines and electrical lines, should you raise the landing gear.

Not quite. The answer is you couple the third trailer to the second trailer before you couple them to the first trailer.

A triple combination vehicle has four units (not counting the converter dollies): a tractor and three trailers. You couple a triple as follows: 1. Couple the first trailer to the tractor the same way that you couple any combination vehicle. 2. Couple the third trailer to the second trailer using the method for coupling doubles (which will involve the use of a converter dolly). 3. Move another converter dolly into position. 4. Couple the tractor and first trailer to the second and third trailer using the method for coupling doubles (which will involve another converter dolly).

Not quite. The answer is Open at the rear of the front trailers and closed at the rear of the last 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 flow 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 the vehicle is more likely to roll over or jackknife.

A double or triple combination vehicle is more likely to roll over or jackknife from 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 slightly raised.

When connecting the rear trailer to the converter dolly, lock the trailer brakes and raise the trailer landing gear slightly off the ground so it won't be damaged if the trailer moves. Then pull forward with the trailer brakes still locked, to check that the rear trailer is locked onto the converter dolly. If it's not, at least the landing gear will keep the rear trailer from falling onto the ground.

Not quite. The answer is use controlled or stab braking.

Hard braking and turning at the same time is likely to cause a skid. You should brake in a way that will keep your vehicle in a straight line and allow you to turn if necessary. If you need to brake suddenly to avoid a crash, use controlled braking or stab braking (but don't use stab braking if your vehicle has antilock brakes).

Not quite. The answer is closed; latched

When you do a walk-around inspection, you must ensure that the converter dolly is properly connected to the front trailer. Check that the pintle hook of the front trailer is locked onto the eye hook of the converter dolly and properly latched. Otherwise, the dolly could come loose. Even worse, if the dolly comes loose while it's still coupled to the rear trailer, the tow bar could fly up, possibly injuring someone.

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 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 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 slowly pull clear of the converter dolly.

The last step in the process of uncoupling twin trailers is to slowly pull clear of the converter dolly. The other two choices are previous steps in this process.

Not quite. The answer is Both (a) and (b)

Take special care when pulling two or three trailers. In bad weather, under slippery conditions, and in mountain driving, you must be especially careful. There is a greater risk of skids and loss of traction. Also, doubles and triples need more space because they can’t be turned or stopped suddenly. Maintain a greater following distance. Make sure you have large enough gaps before entering or crossing traffic.

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 Closed

A pre-trip inspection of a double or triple combination vehicle includes an inspection of each converter dolly. Among other things, check that the converter dolly air tank petcock is closed.

Not quite. The answer is Check your mirrors to keep an eye on your tires.

Use the mirrors to keep an eye on your tires. It's one way to spot a tire fire. But your mirrors don't eliminate all blind spots. Your truck still has large blind spots, often called No-Zones.