CDL Practice Test (#1) – All Endorsements (With Time Limit)

Tankers carrying liquids can roll over more easily than other vehicles. This is because of the tanker’s higher center of gravity and because of liquid surge. Since liquid surge also makes it more difficult to stop or turn a liquid tanker, choices (A) and (B) are incorrect. Because of the tanker’s weight, it is difficult for a tanker to climb a hill, so choice (C) is incorrect.

Sanitation regulations do not permit the use of baffles because these make cleaning the tank more difficult. Therefore, of the choices given here, milk, a food product, would be the most likely load in an unbaffled tanker. Since baffles make a tanker easier to handle, other liquid products, such as gasoline [choice (B)] and liquid nitrogen [choice (C)], would be more likely to be transported in a tank with baffles. Since choice (D) is not a liquid, it is incorrect.

This is a definition of a tank vehicle. Answer choice (A), hazardous liquids, and choice (B), gasoline or other petroleum products, are too specific, since a tank vehicle can be used to transport nonhazardous liquids and products other than petroleum. Answer choice (D), military equipment, is not correct, because it does not fit the definition of materials that can be transported in a tank vehicle.

A baffle is a bulkhead with holes; it doesn’t divide a tank into smaller tanks, but slows the flow of liquid within a single tank, so choice (A) is incorrect. A smoothbore is another name for an unbaffled tank. This means that a smoothbore liquid tank is undivided, so choice (B) is incorrect. Since choice (C), a bulkhead, is the correct answer, choice (D), none of the above, should not be chosen.

Movement of liquid in the tank, called liquid surge, can make handling the vehicle difficult. A loaded tank has a high center of gravity, not a low one, so choice (A) is incorrect. Answer choices (C) and (D), the weight of the vehicle and the length of the vehicle, are true of any loaded vehicle, not only one transporting liquids. Since this question asks about special skills for carrying liquids, these choices are incorrect.

Because a conventional tank is taller than a low-profile tank, it carries its load higher, and this makes it more top-heavy. Therefore, choice (D) is correct. A low-profile tank is wider than a conventional tank, so choice (A) is incorrect. Since a conventional tank is more top-heavy, it will be harder to handle (and therefore less safe) in some situations than a less top-heavy one, so choice (B) is incorrect. Finally, although a conventional tank distributes weight differently from a low-profile tank, it is not necessarily heavier, so choice (C) is incorrect.

Since liquids expand as they warm, space must be left above the liquid when it is loaded into a tank. This space is defined as outage. Liquid cannot travel through a bulkhead between two small tanks, so choice (B) cannot be correct. Answer choices (C) and (D) are not formally defined, so they are both incorrect.

All previously reported defects should be fixed before you sign the previous driver’s report and use a bus for passenger transport. In addition, the front tires should not have been recapped or regrooved, which means choices (A) and (B) are incorrect. All emergency exits must be closed, not open, before driving. Answer choice (C) is incorrect.

For safety, a charter bus cannot have more than eight temporary folding seats. So choices (C) and (D) are incorrect. While four seats are permitted, this is not the maximum allowed. Therefore, choice (A) is incorrect. All other seats must be securely fastened to the bus.

All of the above These materials are regulated by federal agencies to protect persons and property from exposure to substances that could harm them. You must not transport a hazardous material unless the rules allow it.

Federal regulations require you to stop the bus 15 to 50 feet before railroad crossings. Then listen and look in both directions.

For the safety of the passengers, have them leave the vehicle (if possible) when you are refueling. You should never refuel in a closed building with passengers aboard. Therefore, choice (B) is incorrect. It is unwise to talk to passengers while driving since being distracted, even for a few seconds, can lead to an accident. Answer choice (A) is incorrect. Do not tow or push a disabled bus with riders on board either vehicle, unless getting off would be unsafe. Then, only tow or push the bus to the nearest safe spot to discharge passengers. Answer choice (D) is incorrect.

You should never accelerate when going around curves. Answer choice (A) is incorrect. Answer choices (B) and (C) are incorrect because a safe speed for a car may not be safe for a bus. Your speed in a curve should not be determined by other vehicles, but by what is safe for your vehicle. If your bus begins to lean toward the outside, you are going too fast and should slow down.

Scan the interior of the bus, as well as the road ahead, to both sides, and to the rear. Answer choices (A), (B), and (D) are incorrect because they are incomplete. The passengers’ safety is your top priority. Ensuring their safety requires that you be alert to dangers from any direction, and to disruptions or unsafe actions within your bus.

Air brakes use compressed air to make the brakes work. This makes choices (A), (B), and (D) incorrect. Air brakes are a safe way of stopping large vehicles if the brakes are well maintained and used properly.

The three braking systems in the air brake system are emergency, parking, and service. Therefore, choices (A), (C), and (D) incorrect. Some types of brakes are hand-controlled, but this is not the name of a component of the air brake system.

The psi level is set at 150. At this pressure, air must be released to protect the system from serious damage. Answer choices (A) and (B) are pressures too low to activate the safety relief valve. Answer choice (D), 160 psi, is too high for safety.

Spring brakes work by mechanical force. This is a safeguard, so that if the air pressure is too low or all the air leaks out of the system, there will still be a way to stop the vehicle. Therefore, choices (A) and (B) are incorrect. Answer choice (D) is incorrect because it is too high; the spring brakes will come on fully when the air pressure drops to a range of 20-45 psi.

All of the above As with regular brakes, proper adjustment of spring brakes is important to achieving the maximum braking power. The modulating control lever enables you to control braking; the more you move the lever, the harder the brakes come on. Traction is always a factor when braking. On wet or icy roads, braking power will be reduced.

Dual parking control valves allow you to supply enough air for you move your vehicle a short distance to avoid or get out of an emergency situation. So choice (B) is correct. The valve does nothing as far as balancing the pressure in the tanks, so choice (A) is incorrect. If the tanks are low for any reason you should find a safe place to park as quickly as possible because you may have an air leak, so choices (C) and (D) are incorrect.

Pressing and releasing the brake pedal too much can let out the air faster than the compressor can replace it. It will actually take longer to stop your vehicle because there is less pressure, which makes choice (A) incorrect. Answer choice (B) is incorrect because on-and-off braking heats your brakes more quickly than slow, steady braking. The brake pedal does not pump air back into the system; the air compressor does. Thus, choice (D) also is incorrect.

Because the service line controls air going to the trailer brakes when you push the pedal you may not know there is a problem with the service line until you put on the brakes, so choice (C) is correct. The emergency brakes won’t come on because there is still pressure in the trailer air tanks, so choices (A) and (B) are incorrect. Air is going to leak away when you push the brakes, so choice (D) is incorrect.

The fifth wheel plate must be greased as required or steering problems caused by friction may result. The trailer protection valve, glad hands, and the air supply knob are all parts of the air brake system. Any malfunction among them would not cause friction and/ or steering problems, so choices (A), (C), and (D) are all incorrect.

Turning the crank in low gear a few extra turns will lift some weight off the tractor, making it easier for you to unlatch the fifth wheel and couple the next time. Answer choice (A) is only true for empty trailers, and therefore is an inappropriate answer choice for this question. Answer choices (C) and (D) are also incorrect because they list procedures which should specifically not be followed when lowering landing gear.

Attaching glad hands to dummy couplers or to each other will prevent dirt from getting into the glad hands and the air lines. Answer choices (B) and (C) are incorrect because glad hands have no bearing on air supply when not attached to air lines. Answer choice (D) is also incorrect. Glad hands are either color-coded or tagged to keep them from getting mixed up.

The trailer service brake should be tested with the hand valve but operated with the foot pedal. Answer choice (B) is incorrect because the trailer air supply control is not involved in testing the trailer service brake. Answer choice (C) is incorrect because the responses are in the wrong order. Answer choice (D) is also incorrect. The trailer emergency valve tests the trailer emergency brake.

There should be no space between the upper and lower fifth wheel after coupling. If there is any amount of space, the kingpin may be in the wrong place and the tractor could come loose very easily. Answer choices (A), (B), and (D) are all incorrect.

Because pushing in the trailer air supply control supplies air to the trailer air tanks, answer choice (A), pulling out the control, is incorrect. Pressing the trailer hand brake causes pressure in the service line to change, so choice (B) is incorrect. The relay valve sends air pressure from the trailer air tanks to the trailer brake chambers, thus choice (C) is incorrect.

To reduce the risk of rollover, keep the cargo as close to the ground as possible. This is done by spreading out the cargo so that its weight is centered on the vehicle and by loading heavy cargo under light cargo. Since loading the cargo on one side of the truck makes the trailer lean, thereby increasing the risk of rollover, choice (A) is incorrect. Answer choice (C) is also incorrect. Changing lanes quickly causes a “crack-the-whip” effect and increases the risk of rollover. Since choice (B) is the correct answer, choice (D), none of the above, is an inappropriate choice.

Answers choices (A), (B), and (C) are all incorrect. Answer choice (A) is incorrect because you should remove the explosives from your vehicle before separating the vehicles from each other. Answer choice (B) is incorrect because explosives should be placed at least 200 feet from the vehicles and occupied buildings. Answer choice (C) is incorrect because you should keep bystanders away from the vehicles, not ask them to come closer and endanger their lives. Since none of the choices given here is correct, the proper answer is choice (D), none of the above.

Answer choice (B) is correct because these are class A and B explosives and therefore must be placed on a liner that is either non-metallic material or non-ferrous metal. Answer choice (A) is incorrect because a Division 4.1 material is a flammable solid. Answer choice (C) is wrong because Division 6.1 material is a poison, and choice (D) is wrong because divisions 2.1, 2.2, and 2.3 are gasses. None of these requires a floor lining when being transported.

Some substances are hazardous or fatal when not safely packaged. For this reason, if you discover a cargo leak, you should not remain in your vehicle or attempt to find the source of the leak by smell. Answer choices (A) and (C) are incorrect. If you park upwind of people and buildings, any harmful gaseous substances will be carried to where they are. Therefore, you should park downwind, and answer choice (D) is incorrect. Identifying the leaking material by using shipping papers, labels, or package location is a safe and proper technique. Answer choice (B) is correct.

You must stop before crossing railroad tracks if your vehicle has any placards, so answer choice (A) is correct. You must also stop if your vehicle has cargo tanks, whether they are empty or full. Answer choice (B) is also correct. Finally, whenever you are carrying chlorine, you must stop before crossing railroad tracks, so answer choice (C) is also correct. Since all three choices are correct, the answer is (D), all of the above.

A package labeled with any of these three labels should not be loaded in the driver’s cab or sleeper due to the hazards associated with being in close contact with these substances. Although answer choices (B), (C), and (D) contain items that should not be loaded in the cab or sleeper, they are not inclusive. For this reason, these choices are all incorrect.

Answer choices (A), 1 hour, and (C), 50 miles, are too small. Answer choice (B), 3 hours, is too long to wait before rechecking. To ensure that your tires are properly inflated at all times, you must stop and check your tires every 2 hours or 100 miles, whichever is less. The correct answer is choice (D).

Opening the emergency line shut-off valve at the rear of the last trailer is a way of checking that the entire emergency air line system is charged. Both choices (A) and (C) are incorrect because you must open the service line shut-off valve to check whether the service air line has any leaks or is fully charged. Answer choice (D) is incorrect as well. If the other shut-off valves were closed, you would not hear air escaping because there would be no air in the last trailer.

Empty or lightly loaded vehicles have less traction than fully loaded vehicles, making it easy to lock up the wheels. Answer choice (B) is incorrect because it takes longer to stop a vehicle when it is empty than when it is full. Answer choice (C) is incorrect because the suspension springs on lighter vehicles are stiff, not flexible. Empty or lightly loaded vehicles also have a great jackknifing potential, so choice (D) is incorrect as well.

Converter dollies built before 1975 are not required to have spring brakes. Since each converter dolly has at least one air tank, (B) is incorrect. Every air tank, whether on a trailer or dolly, has a drain valve, so choice (C) is incorrect. Because choice (A) is the only correct answer, (D), all of the above, is not an appropriate choice.

In order for air to flow through the first trailer and into the second, you must open the shut-off valves of the first trailer. To keep the air from leaving the vehicle, however, you must close the shut-off valves of the second trailer. Both choices (A) and (C) are incorrect because if the shut-off valves of the first trailer are closed, air cannot flow into the second trailer. Answer choice (B) is incorrect as well. If the shut-off valves are open at the rear of the second trailer, all the air flowing into the front of the second trailer will leak out the rear.

No matter how many trailers you are pulling, you must insure a low center of gravity in each trailer and protect the rig from rollover. To lower the vehicle’s center of gravity, keep the cargo as close to the ground as possible and pile heavy cargo under light cargo. Answer choices (A) and (B) are incorrect because they do not follow these guidelines. Answer choice (D) is also incorrect because uncentered cargo in any trailer will cause the rig to lean and increase the risk of rollover.