District Of Columbia CDL DMV Knowledge Test Class B 1

There may be a delay of a few seconds between the sound of a tire failing and the time that the vehicle is affected by the tire failure. Because of the short delay, a driver may initially believe that the sound came from another vehicle.

A large vehicle may need to swing right to make a left turn. If an intersection has two left turn lanes, the driver should choose the righthand land to begin their turn.

Always change lanes slowly and smoothly. If there is a vehicle in the other lane that you did not see before beginning to move, they will have more time to react to your vehicle.

If you encounter an aggressive driver, the most important thing to do is get out of their way, if possible. Do not provoke the driver by challenging them or making eye contact, and do not let yourself be provoked by rude gestures they might make.

Front-end header boards, also known as "headache racks," protect drivers from moving cargo in the event of a crash or emergency stop.

If cargo is covered, the cover should not flap in the wind in transit. The cover could tear loose, uncovering the cargo while potentially blocking your view or the view of others.

When inspecting a trailer during a vehicle inspection test, ensure that its landing gear has no missing parts and that it is fully raised. The crank handle should be secure and the support frame should not be damaged.

Compressed air in an air brake system usually contains a certain amount of water and compressor oil. The water and oil can damage the brakes if left to accumulate in the system. Manually operated air tank drains must be opened daily to remove this build-up.

The securement of cargo must be checked before beginning a trip, within the first 50 miles of a trip, and then again every three hours or 150 miles.

Loads that are over-length, over-width, and/or overweight may require special permits. Drivers of such loads may be subject to special restrictions, such as only being permitted to drive at certain times.

Air expands as it gets warmer, so the air pressure in your tires could reach dangerously high levels while being used in very hot weather. If this happens, stop and let your tires cool. Do not let air out of the tires, as this could result in the pressure dropping to an unsafe level once the tires cool down.

Subject to certain conditions, a tank endorsement is required to operate a tank vehicle that is used to haul either liquids or gases.

When driving down a steep grade, you should rely primarily on the braking effect of the engine to slow down. To prevent overheating, use your brakes only as a supplement to this slowing technique.

Roads are particularly slippery when it first begins to rain. The water mixes with oil drippings on the road that have not yet washed away, creating a slippery and dangerous mixture.

Intrastate commerce is defined as when you drive a CMV only within a single state, and the cargo you are carrying is not part of a trip that began or will end outside of the state.

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.

If you see, hear, smell, or feel anything that could indicate trouble while you are driving, you should stop and inspect the source of the unusual occurrence.

When using a fire extinguisher, you should stay as far away from the flames as possible and aim at the base of the fire.

Tires need to have at least 4/32 of an inch of tread depth in every major groove on the front tires, and at least 2/32 of an inch of tread depth on other tires.

Driving at night is more dangerous than driving during the day. It is more difficult for drivers to see hazards, the glare of headlights can affect drivers' vision, and there are more fatigued and impaired drivers on the road.

Black ice is a thin layer of ice that is clear enough for the road surface to be seen through it. A road covered in black ice may look like it is merely wet. You should be very careful when temperatures are below freezing and the road looks wet.

During the CDL vehicle inspection test, you must be able to inspect your vehicle and explain to the examiner what you are inspecting and why.

If a tractor-trailer is so equipped, the trailer brake hand valve can be used to stop the vehicle from rolling back when being started from a stop.

If the road appears to be wet but the wheels of other vehicles are no longer generating spray, ice has formed on the road. Drive with extra caution when operating on wet or icy roads.

Always downshift before beginning to drive downhill. Forcing an automatic transmission into a lower gear at a high speed could damage the transmission and also lead to a loss of ability to engine brake. Drive at a speed that will allow you to control your vehicle without overusing your brakes. When determining a safe speed to drive, you should take into account the steepness of the grade, the length of the grade, the weight of your vehicle, road conditions, and weather conditions.

If a vehicle carries red reflective triangles, the driver should place three of them as warning devices when the vehicle is parked on the road.

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.

On flatbed trailers and trailers without sides, cargo needs to be tied down. There should be at least one tie-down for every 10 feet of cargo. Regardless of the size of the cargo, at least two tie-downs must be used.

It is important to observe other drivers' actions and identify clues that a person could be driving impaired. Drivers who have had too much to drink, are sleepy, are on drugs, or are ill can present hazards to other drivers. One sign that a driver may be impaired is that they stop in inappropriate places, such as at green traffic lights.

Wheels and rims with welding repairs are not safe to be used. Replace any damaged wheels and rims.

Before driving, you should always verify that your service brakes are in good working order. Testing the brakes before a trip allows you to locate any problems before you need to brake while on the road.

Aggressive driving is defined as operating a motor vehicle in a selfish, bold, or pushy manner, without regard for the rights or safety of others.

Special equipment, such as warning flags or flashing lights, may be required if you are transporting an over-length load. When transporting such a a load, you will need to acquire the necessary permits. Driving is often limited to certain times.

The securement of cargo must be checked before beginning a trip, within the first 50 miles of a trip, and then again every three hours or 150 miles.

If you lose pressure in a hydraulic brake system, one appropriate response is to shift down into a lower gear. This will help slow the vehicle.