Massachusetts CDL: Tanker Vehicles Practice Test

Not quite. The answer is MC-331

MC-331 cargo tanks carry gases that are liquefied under relatively high pressure (maximum allowable pressure of 100–500 psi). The cargo tank has a circular cross section and rounded ends. These tanks are commonly used to carry such gases as propane and liquefied petroleum gas (LPG).

Not quite. The answer is closed

Federal regulations require you to keep liquid discharge valves on a compressed gas tank closed except when you're loading or unloading the tank. Also, unless your engine runs a pump for product transfer, you must turn the engine off when you're loading or unloading.

Source: 49 CFR § 177.840

Not quite. The answer is 9,000 gallons.

The average capacity of a DOT-406 or MC-306 fuel delivery truck (often called a "gasoline truck") is 9,000 gallons.

Not quite. The answer is a high center of gravity.

It takes special skills to drive a tanker carrying liquid cargo because of the vehicle's high center of gravity and the possibility that the liquid cargo may surge forward and backward or from side to side. Much of a loaded tanker's weight is carried five or six feet above the ground. This makes a tanker top-heavy, which makes it more prone to rollovers than other types of vehicles. Tests have shown that a tank vehicle can roll over at the speed limits posted for curves. The safest way to take a curve in a tanker is to slow down well below the posted speed limit before you enter the curve.

Not quite. The answer is Watch gauges and mirrors and use your senses to check for problems.

During your trip, you should be watching a number of things, such as your mirrors, gauges, instruments, lights, tires, and cargo. Use several of your senses – sight, hearing, smell, and feel – to detect possible trouble.

Not quite. The answer is driving too fast for conditions.

Over-braking and over-steering can cause skids. Both over-braking and over-steering are more likely when you're driving too fast for the current road conditions.

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

Some liquids expand significantly when they warm up. To fill a tank with such a liquid, you must leave some room in the tank (called "outage") to take the expansion. Also, some liquids are so dense that a full load may exceed the legal weight limit. For these reasons, you may not be able to fill your tanks completely.

Not quite. The answer is You should not apply the brakes while turning.

To avoid a crash or other hazard, keep both hands on the steering wheel so you can turn as quickly as possible. However, turn just enough to avoid the hazard. A too-sharp turn risks a skid or rollover. While turning quickly, avoid braking. Braking in a turn can easily lock the wheels and cause a skid.

Not quite. The answer is the distance you can see ahead.

No matter what type of motor vehicle you are driving at night (even a passenger car), you must drive at a speed that lets you stop within the range of your headlights. (In the dark, you have no way of knowing what lies beyond the reach of your headlights.) With low beams, you can see ahead only about 250 feet. Yet if you're driving a vehicle with air brakes at 45 mph, your vehicle's stopping distance may be as long as 346 feet. Hence, with low beams at 45 mph, you will not be able to brake in time to avoid a hazard that you see.

Not quite. The answer is If it has to stay very clean

For transporting food products such as milk, regulations prohibit baffled tanks because of the difficulty of cleaning the inside of a baffled tank.

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

Sudden or hard braking can cause the liquid in the tank to surge forward, pushing your vehicle forward. If you must stop quickly, use controlled or stab braking instead. (However, don't use stab braking if your vehicle is equipped with antilock brakes.)

Not quite. The answer is Always

Escape ramps are designed with soft gravel, upgrades, or both, to slow down vehicles that experience brake failure on a downgrade. Regardless of the type of CMV you're driving, if your brakes have failed, head for one of these escape ramps, which can save lives, equipment, and cargo.

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

Tank vehicles have a high center of gravity, typically five or six feet above the ground. This makes a tanker top-heavy, which makes it more prone to rollovers than other types of vehicles. Tests have shown that a tank vehicle can roll over at the speed limits posted for curves. To take an upcoming curve safely, slow down well below the posted speed limit.

Not quite. The answer is The posted speed for a curve may be too fast for a tank vehicle.

Tank vehicles have a high center of gravity. Much of a loaded tanker's weight is carried five or six feet above the ground. This makes a tanker top-heavy, which makes it more prone to rollovers than other types of vehicles. Tests have shown that a tank vehicle can roll over at the speed limits posted for curves. The safest way to take a curve in a tanker is to slow down well below the posted speed limit before you enter the curve.

Not quite. The answer is can have strong forward-and-backward surge.

Baffles are often used in tanks to reduce forward-and-backward surge. Nevertheless, certain cargoes, such as milk and other liquid food products, must be transported in smooth bore, unbaffled tanks. (Sanitation regulations forbid the use of baffles because they are hard to keep sufficiently clean.) These tanks are liable to have very strong forward-and-backward surge. Be very careful when driving vehicles with such tanks.

Not quite. The answer is Rear

Shut-off valves are used in the service and supply air lines at the rear of trailers used to tow other trailers. These valves permit closing off the air lines when another trailer is not being towed. You must check that all shut-off valves are in the open position except the ones at the rear of the last trailer, which must be closed.

Not quite. The answer is Wet roads can double the stopping distance at any speed.

To control surge, know the stopping distance of your vehicle and brake far in advance of a stop whenever possible. Bear in mind that your vehicle's stopping distance on wet roads will be about double its stopping distance on dry roads.

Not quite. The answer is with holes that let liquid flow through.

Tank baffles are bulkheads with holes through which the liquid can flow, but with less force than in tanks without such baffles. These baffles significantly reduce forward-and-backward surge but not side-to-side surge, so the risk of surge causing a rollover remains.

Not quite. The answer is a rollover.

A side-to-side surge exerts lateral (sideways) forces on the tank. Once a side-to-side surge begins, unless the driver takes action, the tank will keep swaying more and more until the vehicle rolls over.

Not quite. The answer is 70%

It takes special skills to operate a tank vehicle safely. About 70% of tank truck drivers haul hazardous materials, such as gasoline. Doing so takes even more special skills. Such drivers must obtain both a tank vehicle (N) endorsement and a hazardous materials (H) endorsement on their CDLs, or a combination tank vehicle and hazardous materials (X) endorsement.