Vermont CDL: Combination Vehicles Practice Test

Not quite. The answer is Control line and signal line

The service air line is also known as the control line or signal line.

Not quite. The answer is open except for those on the last trailer.

The shut-off valves are located at the rear of each trailer to allow you to stop the air flow there. If there is another trailer behind this one, open the valves to allow air to flow to that trailer; otherwise, close the valves.

Not quite. The answer is makes firm contact with the ground.

When uncoupling a loaded trailer, lower the landing gear until it makes firm contact with the ground. Then crank the landing gear in low gear for a few more turns – just enough to lift some weight off the tractor, but not so much that you lift the trailer off the fifth wheel. This will make it easier to unlatch the fifth wheel now and couple next time.

Not quite. The answer is the emergency and service air lines.

Before backing under the trailer, you must lock the trailer brakes – which means that you first have to make sure that the trailer brakes are working. Connect the emergency and service air lines and test the trailer brakes.

Not quite. The answer is To prevent steering problems

One of the first steps in coupling a tractor to a trailer is to check that the fifth wheel skid plate is greased as required. If the fifth wheel plate is not properly lubricated, friction between the plate and the trailer apron could cause steering problems.

Not quite. The answer is glad hands

As part of your vehicle inspection test, if your vehicle is equipped with air brakes and has a trailer, you will inspect the air connections between the truck or tractor and the trailer. These connections are made with hose couplers (commonly called "glad hands" because they vaguely resemble shaking hands). These glad hands have rubber seals to form a tight connection and prevent air from escaping. Make sure that the glad hands are locked in place and free of damage or air leaks.

Not quite. The answer is it will be raised slightly when the tractor is backed under it.

Before backing the tractor under the trailer, adjust the landing gear to position the trailer at the proper height. The trailer should be just low enough that it will be raised slightly by the tractor when the tractor backs under it. If the trailer is too low, the tractor may hit and damage the trailer nose; if it's too high, it may not couple properly.

Not quite. The answer is Yes, if you're not sure of your path of travel.

Backing a combination vehicle is potentially hazardous. Before you start to back up, check your intended path of travel. Exit the cab and walk around the vehicle. Check your clearance to the sides and overhead, in and near the path of your vehicle.

Not quite. The answer is None

If there is space between the lower and upper fifth wheel after you have finished coupling, something is wrong. Perhaps the kingpin is on top of the closed fifth-wheel jaws, which could result in the trailer coming loose. Don't start to drive until you have identified and fixed the problem.

Not quite. The answer is fully loaded

The weight of cargo helps the wheels get traction. When a combination vehicle is empty or lightly loaded, its braking distance increases. The very stiff suspension springs and strong brakes give poor traction and make it very easy to lock the wheels.

Not quite. The answer is the tractor protection valve to close.

The tractor protection valve keeps air in the tractor if the trailer breaks away or develops a bad leak. If air pressure drops too low in the service line, the tractor protection valve will close. This stops air from escaping from the tractor and lets air out of the trailer emergency line, causing the trailer emergency brakes to come on.

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 slightly raised.

After you've backed under the trailer and locked the kingpin into the fifth wheel, raise the landing gear slightly. Then with the trailer brakes still locked, gently pull the tractor forward to check that the trailer is locked onto the tractor.

Not quite. The answer is Adjust the air supply knob to send air to the trailer brakes. Turn off the engine once the air pressure normalizes. Then listen for the sound of escaping air as the brakes are released.

After coupling, make sure that the air lines are not crossed. To do this, send air to the trailer brakes by adjusting the "air supply" knob to normal. Let the pressure normalize. Then turn off the engine and test the brakes. You should see and hear the brakes in action and then see the air pressure normalize again.

Not quite. The answer is It takes 14 seconds to clear a single track and more than 15 seconds to clear a double track.

You can expect it to take more than 15 seconds for a typical tractor-trailer to clear a double track and at least 14 seconds to clear a single track.

Not quite. The answer is In the rear

The shut-off valves are located at the rear of a trailer, since that is where they must be located to service the air lines. The shut-off valves are open except in the last trailer, in which they are closed.

Not quite. The answer is On the left front or left rear corner

On a trailer, the yellow ABS malfunction lamp is located on the left front or left rear corner. Make sure you know where to look for it.

Not quite. The answer is the trailer emergency glad hand.

During the coupling process, after you've backed the tractor till it's touching the trailer and you've parked the tractor, it's time to connect the air lines. Connect the tractor emergency air line to the trailer emergency glad hand. Connect the tractor service air line to the trailer service glad hand.

Not quite. The answer is two red lights

According to federal regulations, if the load projects more than 4 feet behind the rear of the vehicle, the end of the load must be marked as follows: (1) with two red flags, each 18 inches square, in the daytime; or (2) with two red lights at night. There are additional federal requirements on how to illuminate the rest of the load. US states may impose their own additional requirements on the transportation of oversized loads. You can learn about Vermont's requirements by contacting the Vermont Department of Motor Vehicles or visiting their webpage "Oversize/Overweight" (https://dmv.vermont.gov/document-category/excess-weight). [49 CFR 393.11],

Source: 49 CFR 393.87

Not quite. The answer is get away from your vehicle and call 911 or the posted emergency number.

A train traveling at 60 mph can take more than a mile to come to a complete stop. If your vehicle gets stuck on a railroad track, don't spend any time trying to free your vehicle. Get out of your vehicle and walk quickly at about a 45-degree angle to the tracks in the direction from which you expect trains to approach. That way, if your vehicle is hit, you won't be struck by flying debris. Call 911 or the telephone number on the railroad crossing sign for assistance.