West Virginia CDL: Double & Triple Trailers Practice Test

Not quite. The answer is A truck has less traction when it's empty than when it's fully loaded.

Trucks that are empty or only lightly loaded take longer to stop because the stiff suspension springs and strong brakes give poor traction and make it easier to lock the wheels.

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 foot pedal.

You can use the trailer hand valve (also known as a spike or Johnson bar) to test the trailer service brakes. During normal driving, however, all the service brakes on your vehicle are controlled with the foot pedal, which applies air to the service brakes at all the wheels.

Not quite. The answer is If there are vehicles on both sides of you, a move to the right may still be best.

To avoid a head-on collision, steer right toward the shoulder or curbline. Even if you are blocked on both sides by other vehicles, a move to the right may still be best. At least you won't force other drivers into an opposing traffic lane, possibly involving them in a head-on collision. Prepare to drive entirely off the roadway to the right if necessary to avoid a head-on collision. Head-on collisions are often fatal.

Not quite. The answer is Open the air tank petcock.

You release the dolly's brakes by opening the air tank petcock or (if the dolly is equipped with spring brakes) using the dolly's parking brake control.

Not quite. The answer is How the rear wheels follow a different path from the front wheels in a turn

Off-tracking is defined as the different paths taken by the front and rear wheels in a turn. The longer the vehicle, the greater the difference will be. As a result, the path followed by a tractor will be wider than the path of the rig itself. To compensate, you must steer the tractor wider to keep the rig from overrunning the curb or hitting some object.

Not quite. The answer is closed.

To uncouple the second trailer, start by applying the parking brakes to keep your vehicle from moving. Lower the landing gear of the second trailer. Close the shut-off valves at the rear of the first trailer (and on the dolly if so equipped) to keep air from going out of the vehicle. Then disconnect the dolly air and electric lines, release the dolly brakes, and release the dolly fifth wheel latch. You are now ready to pull the first trailer and the dolly away from the second trailer.

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 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 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 Turnpike double trailer

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 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 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 One second for every ten feet of your vehicle

The usual formula for following distance under ideal conditions is one second for every ten feet of vehicle length, plus an extra second if you are traveling at over 40 mph.

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 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 The more sharply you turn, the greater the chances of a skid or rollover.

Don't turn any more than needed to clear whatever is in your way. The more sharply you turn, the greater the chances of a skid or rollover.

Not quite. The answer is a coupling device that connects a semitrailer to the rear of a tractor-trailer.

The converter dolly connects a semitrailer to the rear of a tractor-trailer, forming a double or triple combination.

Not quite. The answer is The dolly tow bar may fly up.

If you unlock the pintle hook while the dolly is still underneath the rear trailer, the dolly's tow bar may fly up, making it harder to recouple and possibly injuring someone.

Not quite. The answer is the tractor protection valve control (trailer air supply control) will pop out or go from "normal" to "emergency."

When you test the tractor protection valve, the tractor protection valve control (also called the trailer air supply control) should pop out or go from the "normal" to the "emergency" position. This shows that the tractor protection valve has closed automatically to keep the air pressure from falling too far.

Not quite. The answer is directly in front of the converter dolly.

Back the first trailer into position in front of the tongue of the dolly. Hook the dolly to the pintle hook on the first trailer. Then latch the pintle hook securely. Raise the dolly's landing gear.