South Carolina CDL DMV Knowledge Test Class B 2

Backing is always dangerous because it is impossible to see everything that is behind your vehicle. Only drive in reverse if it is absolutely necessary.

The parking brake should be applied every time you park your vehicle.

If you must drive in fog, be sure to slow down. Turn on your flashers and low beam headlights.

Avoid being an aggressive driver by being realistic about your travel time, making allowance for delays, maintaining reasonable following distances, and not making hand gestures that could anger another driver.

Always speed up smoothly and gradually so that your vehicle does not jerk. Rough acceleration can cause mechanical damage.

Being under stress can lead to aggressive driving, which is dangerous. Playing calming music can help you become more relaxed if you are feeling stressed while driving.

It is prohibited for CMV drivers to use hand-held mobile phones while driving.

In an air brake system, a low pressure warning signal should activate if the pressure in the air tanks falls to a level below 60 psi. This signal may be in the form of a warning light or a wig wag.

It is always important to have enough water and antifreeze in a vehicle's cooling system. Despite the name, antifreeze is beneficial to an engine even in hot weather.

Potential warning signs of fatigue include difficulty focusing, frequent blinking, or heavy eyelids; yawning repeatedly or rubbing your eyes; daydreaming; wandering or disconnected thoughts; trouble remembering the last few miles you've driven; missing exits or traffic signs; having trouble keeping your head up; drifting from your lane; following too closely; hitting a shoulder rumble strip; or feeling restless and irritable.

A maximum posted speed limit is the fastest a vehicle may travel under ideal circumstances. A driver should decrease their driving speed as conditions require. A driver should never exceed the legal speed limit.

An Anti-Lock Braking System (ABS) helps prevent wheels from locking up during a hard application of brakes.

Never push down the brake pedal while the spring brakes are activated. The combined force of springs and air pressure could damage the brakes.

Most heavy-duty vehicles use dual air brake systems, in which there are two separate braking systems operated by a single set of controls. Each system operates the brakes on different axles.

Truck tractors with air brakes built on or after March 1, 1997 must be equipped with Anti-Lock Braking Systems (ABS).

Ice becomes wet when the weather is just warm enough to melt the ice slightly. Wet ice is much more slippery than ice that is not wet.

Weight of cargo should be loaded into a trailer as low as possible. If the weight of cargo is positioned too high in a trailer, it will put the vehicle at risk of tipping over.

Be sure to activate the appropriate turn signal well in advance of a turn or lane change. Signal continuously throughout the turn and make sure to cancel the signal after the turn is completed, if your vehicle doesn't have self-canceling signals.

Always drive cautiously around a stopped bus. Passengers may cross in front of or behind it, and the bus may prevent them from seeing your vehicle.

When inspecting your brakes, you should verify that the shoes and pads do not have any oil, grease, or brake fluid on them.

To prevent drowsiness on a long trip, strategies include getting adequate sleep beforehand; planning out the route and stopping points in advance; driving with a passenger; and driving at times during which you are normally awake.

When inspecting an exhaust system, you should verify that parts of the system are not loose, broken, or missing. The system's parts must be properly mounted and should not be rubbing against moving parts of the vehicle.

Reduce your speed when traveling on surfaces that provide reduced traction. Reduce your speed by one-half or more when traveling on packed snow.

A steering wheel should be held firmly with both hands, positioned on opposite sides of the wheel.

It is important to inspect your tires before every drive. Rust around wheel nuts may indicate that they are loose.

Gross Combination Weight (GCW) is the total weight of a powered unit, its trailer(s), and the cargo being carried.

When checking a cargo lift as part of your vehicle inspection test, you should check for leaking, damaged, or missing parts. The lift must be fully retracted and latched securely.

The parking brake in a vehicle with air brakes should be used every time the vehicle is parked.

Blocking may be used on all sides of a piece of cargo to keep it from sliding while the vehicle is in motion.

Check your engine during the pre-trip inspection. After starting the engine, you should listen for unusual noises.

Before driving a vehicle with air brakes, you should ensure that the spring brakes come on automatically when air tank pressure falls to a level between 20 and 45 psi. You can do this by chocking the wheels and releasing air from the braking system by stepping on and off the brake pedal. Once the pressure levels drop to an unsafe level, the parking brake valve should pop out and spring brakes should come on.

In an air brake system, there are three different braking systems: a service brake system, a parking brake system, and an emergency brake system. The emergency brake system uses parts of both the parking and service brake systems.

Your application for a hazardous materials endorsement can be denied, or your existing endorsement canceled, if you do not have legal permanent status in the United States; you renounce U.S. citizenship; you are wanted for, under indictment for, or convicted of certain felonies; you are judged mentally incompetent or are involuntarily committed to a mental institution; or you are deemed by the Transportation Security Administration to pose a security threat.

Always drive with caution through work zones. You should make a particular point of reducing your speed when workers are on or near the roadway.

Wheels or rims with welding repairs are never safe to use.