Nebraska CDL: Tanker Vehicles Practice Test

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 Read the vehicle's manual to learn how to do it.

Tank vehicles come in many models and sizes, each with special items that you need to check during an inspection. Read the vehicle's manual to learn how to inspect it properly.

Not quite. The answer is on slippery roads.

When you're coming to a stop, the liquid in the tanks tends to surge forward. If you're on a slippery surface, the surge may shove your truck forward into another vehicle or an intersection. Learn how your tanker handles in such situations.

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 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 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 Your brakes may fail because of water freezing.

Your air tanks hold a mixture of water and compressor oil. If left inside to collect at the bottom, the water may freeze and cause brake failure.

Not quite. The answer is Unstable loads such as hanging meat or livestock can require extra caution on curves.

Hanging meat can sway on curves, and livestock can move around. These motions can affect the handling of your vehicle. One reason that you must drive a tanker vehicle carefully is that liquid surge can push the vehicle in the same direction as the surge. This can be especially hazardous on icy roads, where your truck may be pushed forward a dangerous amount, maybe past a red light into an intersection. Another concern is that liquid expands when it warms. Outage is the space in the tank that must be allocated to handle the expansion. Different types of liquids expand by different amounts. Therefore, the amount of outage you will need depends on the type of liquid.

Not quite. The answer is can affect the handling of your vehicle.

Liquid surge can greatly affect your vehicle's handling. Surge can push the vehicle in the same direction as the surge. This can be especially hazardous on icy roads, where a truck may be pushed forward a dangerous amount, maybe past a red light into an intersection. On curves, side-to-side surge can cause a rollover even when traction is good.

Not quite. The answer is baffles.

Baffles are devices that regulate the flow of liquid. In a tank vehicle, baffles are a type of bulkhead with holes through which liquid may flow but with reduced force.

Not quite. The answer is partly engage the clutch before you take your right foot off the brake.

When you start your vehicle, avoid rolling backward or else you may hit someone behind you. Set the parking brake whenever necessary to keep from rolling back. Release the parking brake only when you have applied enough engine power to keep from rolling back. If you have a manual transmission vehicle, partly engage the clutch before you take your right foot off the brake. On a tractor-trailer equipped with a trailer brake hand valve, the hand valve can be applied to keep from rolling back.

Not quite. The answer is Keep a steady foot on the brake and don't release the brake too soon.

To control the effects of surge, brake far in advance of a stop. Maintain steady pressure on the brakes and don't release them too soon.

Not quite. The answer is If the wheels are skidding, you cannot control the vehicle.

In an emergency, avoid hard braking. Hard braking can lock the wheels, which may cause a skid and loss of control. Instead, use stab braking (unless your vehicle has antilock brakes) or controlled braking.

Not quite. The answer is S-cam drum brake.

Foundation brakes are present on each wheel. In North America as of this writing, S-cam drum brakes are much more common than wedge or disc brakes.

Not quite. The answer is There will be less front-to-back surge than there is in a tanker without baffles.

Baffled tanks have bulkheads with holes to reduce forward-and-backward surge. This will reduce the chance that forward surge will push your vehicle dangerously forward when you're slowing or stopping. However, these bulkheads don't significantly reduce side-to-side surge, so rollovers can still occur.

Not quite. The answer is some liquids expand more than others when they get warm.

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 how much outage you will need to allow for the type of liquid you'll be hauling.

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 there is an even distribution of weight.

Some liquid tanks are divided into several smaller tanks by bulkheads. When loading and unloading the smaller tanks, pay attention to weight distribution. Don’t put too much weight on the front or rear of the trailer.

Not quite. The answer is 5 mph slower.

On a steep downgrade, don't keep applying your brakes continuously because this might cause them to fade (become less effective). Instead, apply your brakes sparingly as a supplement to engine braking. Select a "safe" speed. Let your vehicle reach this speed. Brake gently until you are going 5 mph slower. Then let your speed increase back to the "safe" speed. Keep varying your speed up and down this way. This technique is known as snub braking or snubbing.

Not quite. The answer is allowance for expansion of liquid.

When liquid heats up, it expands, and outage is the space in the tank that is allocated to handle the expansion. Different types of liquids expand by different amounts. Therefore, the amount of outage you will need depends on the type of liquid.