Washington CDL DMV Knowledge Test Class B 1

When making a left turn, you should wait until you reach the center of the intersection before actually beginning to turn. Due to off-tracking, the left side of your vehicle could hit another driver if you begin turning too early.

You should accelerate very gradually when driving under conditions that create poor traction.

Many large vehicles have curved, convex mirrors. Convex mirrors allow drivers to see a wider area than flat mirrors. However, they also make objects seem smaller and farther away than they really are.

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.

In an air brake system, the air tanks must be periodically drained to remove accumulations of water and compressor oil. If water is not removed, it could freeze in cold weather and cause brake failure.

The allowable gross weight of a bus or truck depends on its tire size, the number of axles, and the spacing of axles (or axle groups). In Washington State, the weight of a commercial vehicle is limited to no more than 20,000 pounds on any single axle.

If you must drive so slowly that you will impede the flow of traffic, you should turn on your four-way flashers to alert drivers behind you (as long as local laws allow the use of flashers).

In a vehicle with dual parking control valves, there is a separate air tank that can be used to temporarily release the spring brakes if they have been activated due to low air pressure. Pushing in the proper control will release the spring brakes for a short period of time, allowing the driver to move the vehicle in an emergency.

Because air takes time to flow through the air lines to the brakes, air brakes cannot begin working instantly. There is often a brake lag of at least one-half of a second between the moment the brake pedal is pressed and the moment the brakes begin to work.

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

Black ice is a layer of ice that is thin and clear enough for the road to be visible through it. The surface will look like a wet road. Always be alert to black ice if the road looks wet when the temperature is below freezing.

If your brakes fail on a downgrade, you will have to look outside your vehicle for a way to stop. Using an escape ramp is the safest way to stop your vehicle.

If you are found to have any detectable amount of alcohol in your system while operating a CMV but your blood alcohol concentration (BAC) is still below the legal limit of 0.04 percent, you will be put out-of-service for 24 hours. It is both illegal and dangerous to operate a motor vehicle while under the influence of alcohol.

You must always wear a safety belt while operating a commercial motor vehicle. Driving a CMV without being properly restrained by a safety belt is both illegal and dangerous.

The air storage tanks in an air brake system store compressed air to be used for braking. They hold enough air for the brakes to still be used several times if the compressor stops working.

Drum brakes are attached to the wheels and located on the axles of a vehicle. The braking mechanisms that cause the vehicle to stop can be found inside of a drum brake.

Blocking and bracing are used to prevent cargo from shifting in transit. Blocking is used in the front, in the back, and on the sides of a piece of cargo to prevent movement. Bracing prevents movement by reaching from the upper portion of a piece of cargo to the floor and sides of the cargo compartment.

A broken exhaust system can let poisonous fumes into a vehicle's cab or sleeper berth. Be sure to inspect your exhaust system for any loose, broken, or missing parts.

The purpose of an Anti-Lock Braking System (ABS) is to prevent a vehicle's wheels from locking up when the driver brakes hard on a slippery surface.

If you need to make an emergency stop, you can use either the controlled braking method or the stab braking method. It's important to brake in a way that keeps your vehicle in a straight line but will still allow you to turn if necessary.

During the on-road driving test, the examiner will be scoring you on specific driving maneuvers, as well as your general driving behavior.

Friction inside a brake drum is caused when the brake shoes and linings push against the inside of the drum. The friction in the drums will slow and stop the vehicle.

As you exit your vehicle during the basic vehicle control skills test, you must face the vehicle and maintain three points of contact at all times. If your testing vehicle is a bus, you must maintain contact with the handrail. Exiting the vehicle incorrectly may result in automatic failure of the basic control skills test.

When checking your vehicle's pedals during a pre-trip inspection, you should ensure that there is nothing under or around the pedals that will obstruct their use. Make sure the pedals are in proper working condition and that the surfaces of the pedals are grooved, if applicable.

It is best not to avoid driving in fog. However, if you must drive under foggy conditions, be sure to decrease your speed.

Brake linings should not be loose or soaked with oil or grease. They shouldn't be dangerously thin.

When stopped on the side of the road, be sure to turn on your vehicle's four-way emergency flashers, especially during times of lowered visibility. Place warning devices within 10 minutes of being stopped.

Blocking is used in the front, in the back, and/or on the sides of a piece of cargo to keep it from sliding while the vehicle is in motion.

Front wheel braking is effective under all road conditions. It is unlikely that you will experience a front wheel skid, even on ice.

Cargo should be restrained by at least one tie-down for every 10 feet of cargo. However, all cargo should have at least two tie-downs, no matter the size of the cargo.

In Washington State, a double-trailer combination may not exceed 61 feet in length.

B:C fire extinguishers are designed to work on electrical fires and burning liquids. Don't pour water on an electrical fire.

If the low air pressure warning signal comes on while you are operating a vehicle with air brakes, you should stop and safely park the vehicle as soon as possible. It is essential that you are able to stop safely while you still have some braking power remaining.

Always decrease your speed when traveling through a construction area. Slow down even further if there are workers on or near the roadway.

When parking on a level surface, you should use wheel chocks. If the vehicle is not equipped with spring brakes, this is essential to prevent the trailer from moving.