Oklahoma CDL: Tanker Vehicles Practice Test

Not quite. The answer is Much of the tanker's weight is high up off the ground.

An object with a high center of gravity is top-heavy; much of its weight is high off the ground. Top-heavy objects are more prone to toppling over. Loaded tankers tend to have a high center of gravity because the tanks are so tall. This makes liquid tankers more prone to rolling over. Tests have shown that tankers can roll over on curves even at the speeds posted. On curves, slow down well below the posted speeds.

Not quite. The answer is At the start of each trip and each time you stop

If you have a placarded trailer with dual tires, you should check the tires at the start of each trip and each time that you stop for any reason, whether to rest or to refuel. Use a tire pressure gauge to get an accurate reading.

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 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 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 you have to press the brake pedal harder than usual to control your speed.

If your brakes begin to fade, you'll notice that you have to depress the brake pedal harder to achieve the same braking effect as before. If your vehicle is so equipped, check the application pressure gauge to see just how much pedal effort you are employing. If the brakes continue to fade, you may not be able to slow down or stop at all.

Not quite. The answer is the front or the rear

Bulkheads help separate the load. When loading such tanks, distribute the weight evenly. Avoid putting too much weight on the front or the rear of the vehicle.

Not quite. The answer is joints.

When you're checking the pipes, connections, and hoses of your tank vehicle for leaks, you should pay special attention to joints. Pipe joints are among the weakest points in a piping system. Joints can deteriorate over time and start to leak.

Not quite. The answer is Before loading it, driving it, or unloading it

You should inspect a tank vehicle before loading it, driving it, or unloading it. This is to ensure that it is safe to carry out these activities and the vehicle can safely hold its liquid or gas contents.

Not quite. The answer is the movement of the liquid.

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. The liquid surge can push the vehicle dangerously forward or sideways, which can cause a rollover. 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 closed before you drive the vehicle.

To help prevent leaks, close all manhole covers before you drive the vehicle.

Not quite. The answer is the type of liquid.

Different liquids expand at different rates as the temperature increases. In science, the percentage increase of expansion for a given change in temperature is called the coefficient of thermal expansion. This value depends on the type of liquid. You need to find out the likely percentage increase for the type of liquid you'll be hauling, and allow enough room (called outage) for the expansion to take place.

Not quite. The answer is You should avoid backing whenever you can.

Backing up a large vehicle is always dangerous, even with a helper. Try to avoid backing up as much as possible.

Not quite. The answer is surging.

When a tank is not completely filled, the liquid has room to move around. It can slosh back and forth or side to side. This is called surging.

Not quite. The answer is Slow to a safe speed before entering, then accelerate slightly through the curve.

The posted speed for a curve may be safe for cars but not for tankers because of their relatively high center of gravity. Tests have shown that a tanker can roll over on a curve when traveling at the posted speed. The safest way to take a curve in a tanker is to slow down before the curve and then accelerate slightly through the curve. Braking in a curve risks a skid.

Not quite. The answer is roll over.

Baffled tanks can control back-and-forth surge but not side-to-side surge. During sudden steering changes, side-to-side surge can cause your tanker to roll over. Avoid such sudden moves when possible.

Not quite. The answer is both a hazardous materials (H) endorsement and a tank vehicle (N) endorsement.

A tank vehicle (N) endorsement qualifies you to haul liquids or gases. However, if those liquids or gases are classified as hazardous materials, you must also have a hazardous materials (H) endorsement to haul them. To obtain each of these endorsements, you must pass a specialized knowledge test. Note: These days, if you obtain both endorsements, your CDL may include the combined endorsement code X (tank vehicle and HazMat) instead of both H and N.

Not quite. The answer is 4 psi.

One of the most common types of cargo tanks is the DOT-406, typically used for fuel delivery. A semi-truck with a DOT-406 mounted to the semitrailer is commonly called a "gasoline truck." DOT-406 tanks have a low maximum allowable working pressure (MAWP) of 4 psi.

Not quite. The answer is You should avoid traveling alongside other vehicles whenever possible.

Whenever another vehicle is traveling alongside yours, there's always a chance that the vehicle might try to move into your lane and accidentally hit your vehicle. Also, the vehicle is blocking you from changing lanes. It's safer to find an open spot where there are no vehicles on either side of you. (Of course, that may not be possible in heavy, congested traffic.)