Instructions

Knowledge Test Class A

This license is required for driving any legal combination of vehicles, with a gross combination weight rating of 26,001 pounds or more, provided the GVWR of a trailer exceeds 10,000 pounds To receive this license, applicants must pass a 50-question test. To pass, applicants must answer 40 questions correctly. Each question has two, three or four possible answer choices. Test questions come from the South Carolina Commercial Driver License Manual. Questions come from chapters covering: Introduction, Driving Safely, Transporting Cargo Safely, Air Brakes (if applicable), Combination, Doubles and Hazardous Materials. Endorsements that may be used with a Class A CDL are: Hazardous materials, Tank, Passenger, HazMat and Tank, Air Brakes and School bus.

Number of Question 50

Passing Score 40

1. If you are not sure if there is enough space for your vehicle to safely pass under a bridge, you should:

Speed up.

Swerve as you pass under the bridge.

Slow down.

Drive on the shoulder.

If you are not sure that you have enough room to safely fit underneath a bridge or other overhead object, you should slow down and seek an alternate route, if possible.

2. What can change the height of a vehicle?

Color

Length

Weight

Number of windows

The added weight of a heavy load will make a vehicle sit lower than usual. A vehicle will often be taller when carrying a light load than when carrying a heavy load. If your vehicle fits under an overpass while carrying a full load, it is not guaranteed that it will fit under the same overpass if it is empty.

3. An air compressor governor will stop the compressor from pumping air once the air tanks have an air pressure level of:

125 psi.

100 psi.

150 psi.

80 psi.

An air compressor governor will stop the compressor from pumping air once the air tanks are at an air pressure level of 125 psi. This air pressure level is referred to as the "cut-out" level.

4. How much water must be on a road surface for a vehicle to hydroplane?

Usually several inches

A good amount, such as a large puddle

A small amount

None

Hydroplaning is an effect in which a vehicle's tires lose traction with the surface of the road and instead glide along a layer of water. There does not have to be much water on the road for this to occur.

5. What color is the low air pressure warning light?

Green

Orange

Red

Purple

A low air pressure warning signal is required in vehicles with air brakes. The warning light is usually red and may be accompanied by a buzzer.

6. Texting while driving is especially dangerous because:

It is both a mental and physical distraction.

A message may be upsetting to the driver.

People like to read and may become too engaged in their phones.

Texting while driving is particularly dangerous because it is both a mental and physical distraction to the driver. In addition to diverting a driver's mental attention away from the road, texting requires a person to remove at least one hand from the vehicle's controls.

7. Talking on a hands-free phone while driving:

Does not distract the driver.

Only distracts the driver if the driver is speaking.

Can be distracting to the driver.

While speaking on a hands-free phone while driving is less dangerous than speaking on a hand-held phone, it is just as likely to mentally distract a driver. Simply engaging in conversation takes their mental focus away from the task of driving.

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