Louisiana CDL: Double & Triple Trailers Practice Test

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.

Not quite. The answer is Older models may lack spring brakes.

All converter dollies built since 1975 are required to have spring brakes. All converter dollies built since 1998 are required to have antilock brakes as well.

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 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 leaks of air or hydraulic fluid

Check the landing gear as part of your walk-around inspection. Check that no parts are missing and it isn't bent or damaged. If the landing gear is power operated, check its hoses, fittings, and other parts for signs or sounds of escaping air or hydraulic fluid.

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.

Not quite. The answer is to lower its landing gear.

After you have uncoupled the rear trailer from the converter dolly, you need to uncouple the converter dolly from the front trailer. You do this as follows: 1. Lower the landing gear of the dolly. 2. Disconnect the safety chains. 3. Apply the dolly's spring brakes or chock its wheels to keep the dolly from moving. 4. Release the pintle hook connecting the dolly to the trailer ahead of it. 5. Slowly pull clear of the dolly.

Not quite. The answer is both of the above are true.

Check each landing gear to be sure that it is fully raised. Also check that no parts are missing and it isn't bent or damaged.

Not quite. The answer is Overloaded front axles can make the steering axle weight too light to steer safely.

Underloaded front axles (caused by shifting weight too far to the rear) can make the steering axle weight too light to steer safely.

Not quite. The answer is The pintle eye of the dolly should be in place in the pintle hook of the trailer.

A pre-trip inspection of a double or triple combination vehicle includes an inspection of each converter dolly in the vehicle. Among other things, check the coupling of the dolly to the trailer in front. Make sure that the pintle eye of the dolly is in place in the pintle hook of the trailer, and the pintle hook is latched closed.

Not quite. The answer is Go to the rear of the second trailer and open the emergency line shut-off valve.

To check whether air is being supplied to the second trailer, go to the rear of the trailer and open the emergency line shut-off valve. You should hear air escaping, indicating that the entire system is charged up to that point. (For a triple combination vehicle, perform this procedure with the third trailer.)

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 Neither of the above will cause it.

Despite what footnote 5 in 49 CFR 393.11 says, Operational Policy 15 of the North American Standard Out-of-Service Criteria states that a converter dolly must have one stop lamp, one tail lamp, and (if the dolly obscures the tractor's rear turn signals) turn signal lights, but only when the dolly is being towed singly and is not towing a trailer. In a full multi-trailer configuration, the rearmost trailer must have working stop lights and taillights, of course.

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 Brake and downshift in the curve.

Before entering a curve, slow down to a safe speed and downshift into the right gear. This lets you use some power through the curve to help keep the vehicle stable through the curve. It also allows you to speed up as soon as you are out of the curve.

Not quite. The answer is foot pedal.

The trailer hand valve (also called the Trolley Valve or Johnson Bar) operates only the trailer brakes, not the tractor brakes. Hence, use it only when you want to test the trailer brakes. Don't use it in normal driving because braking the trailers and not the tractor can cause a trailer to skid. The foot brake sends air to all the brakes on the vehicle – the tractor and all trailers. There is much less danger of causing a skid or jackknife when using just the foot brake.

Not quite. The answer is March 1998.

Antilock brakes have been required on all tractors built since March 1, 1997. Antilock brakes have been required on all trailers, converter dollies, buses, and single trucks built since March 1, 1998.

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 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 air escape from the open valve.

Test the trailer brakes by opening the service line valve at the rear of the rig. You should hear the telltale hiss of air escaping. If you don't, it means that air is not flowing through the entire line, and you will need to investigate.