CDL School

While you are at the front of the vehicle, check the following items: headlight, low and high beam; windshield wiper arms for proper spring tension; wiper blades for damage; reflectors.

Use windshield washer antifreeze to prevent freezing of the washer liquid.

If you find yourself being tailgated: avoid quick changes, signal early, reduce speed very gradually, increase your following distance, and don't speed up.

In a front-wheel skid, the front end tends to go in a straight line regardless of how much you turn the steering wheel.

Preventing drowsiness before a trip: Get adequate sleep (8 to 9 hours), prepare route, schedule trips for the hours you are normally awake, drive with a passenger, avoid medications that cause drowsiness.

The gross combination weight (GCW” is the total weight of the GCWs of each unit of a combination vehicle – truck/tractor and trailer(s) added together.

Explanation: Use high beams when it is safe and legal to do so. Use them when you are not within 500 feet of an approaching vehicle. 

Explanation: Warn following drivers by flashing your brake lights, don't stop suddenly. If you see a hazard that will require slowing down, warn the drivers behind by flashing your brake lights. At dawn, dusk, in rain, or snow, you need to make yourself easier to see so turn on your lights. 

Explanation: To drive a vehicle safely, you must be able to control its speed and direction. Safe operation of a commercial vehicle requires skill in accelerating, steering, stopping, and backing safely.

Low air warning devices (buzzer, light, flag) should activate before air pressure drops below 60 psi or level specified by the manufacturer.

Braking when a tire has failed could cause loss of control. Unless you're about to run into something, stay off the brakes until the vehicle has slowed down. Then brake very gently, pull off the road, and stop.

Accident statistics show that the chance of a crash is much greater for drivers who have been drinking than for drivers who have not.

In some vehicles, a control handle on the dashboard may be used to apply the spring brakes gradually. This is called a modulating valve. It is spring loaded, so you have a feel for the braking action. The more you move the control lever, the harder the spring brakes become on. They work this way, so you can control the spring brakes if the service brakes fail.

Explanation: ¾ second to 1 second. At 55 mph this accounts for 61 feet traveled.

If the surface is icy, reduce speed to a crawl and stop driving as soon as you can safely do so.

Blocking is used in the front, back, and/or sides of a piece of cargo to keep it from sliding. Blocking is shaped to fit snugly against cargo. It is secured to the cargo deck to prevent cargo movement.

Explanation: The gear box is part of the steering system, and other choices are parts of the suspension system.

Stopping is not always the safest thing to do in an emergency. When you don't have enough room to stop, you may have to steer away from what's ahead. Remember, you can almost always turn to miss an obstacle more quickly than you can stop.

Wedge brakes and disc brakes are less common than s-cam brakes.

Too much weight on the steering axle can cause hard steering. It can damage the steering axle and tires.

The B:C type fire extinguisher is designed to work on electrical fires and burning liquids. These are usually the following types of fire extinguishers: Regular Dry Chemical, KCl Dry Chemical, Carbon Dioxide (Dry), Halogenated Agent (Gas).

The governor controls when the air compressor will pump air into the air storage tanks. When air tank pressure rises to the "cut-out" level around 125 psi, the governor stops the compressor from pumping air. When the tank pressure falls to the "cut-in" pressure around 100 psi, the governor allows the compressor to start pumping again.

The total stopping distance is the total minimum distance your vehicle has traveled, in ideal conditions; with everything considered, including perception distance, reaction distance and braking distance, until you can bring your vehicle to a complete stop. At 55 mph, your vehicle will travel a minimum of 450 feet.

If the load is more than two feet wide and extends more than four feet behind the rear of the vehicle, two square red flags must be placed at the end of the load.

You should brake in a way that will keep your vehicle in a straight line and allow you to turn if it becomes necessary. You can use the "controlled braking" method or the "stab braking" method. 

Inspect the cargo and its securing devices again within the first 50 miles after beginning a trip. You need to inspect again after you have driven for 3 hours or 150 miles and after every break you take while driving.

Air brakes are three different systems: service brake, parking brake, and emergency brake.

Your CDL will be disqualified after two or more convictions of any state law on texting while operating a CMV. No motor carrier shall allow or require its drivers to engage in texting while driving.

Explanation: If you stop on a two-lane road carrying traffic in both directions or on an undivided highway, place warning devices within 10 feet of the front or rear corners to mark the location of the vehicle and 100 feet behind and ahead of the vehicle, on the shoulder or in the lane you stopped in.

You need at least one second for each 10 feet of vehicle length at speeds below 40 mph. At greater speeds, you must add 1 second for safety. If your vehicle is 40 feet long and you are traveling at 50 mph, your following distance should be 5 seconds or more.

The tire load is the maximum safe weight a tire can carry at a specified pressure. This rating is stated on the side of each tire.

Without ABS you still have normal brake functions. Drive and brake as you always have.

To know how much space you have, wait until the vehicle ahead passes a shadow on the road, a pavement marking, or some other clear landmark. Then count off the seconds like this: "one thousand-and-one, one thousand-and-two" and so on, until you reach the same spot.

All vehicles with air brakes have a pressure gauge connected to the air tank. If the vehicle has a dual air brake system, there will be a gauge for each half of the system.

Heavy vehicles are often tailgated when they can't keep up with the speed of traffic. This often happens when you're going uphill. If a heavy load is slowing you down, stay in the right lane if you can. Going uphill, you should not pass another slow vehicle unless you can get around quickly and safely.

Whether or not you load and secure the cargo yourself, you are responsible for inspecting your cargo, recognizing overloads and poorly balanced weight, knowing your cargo is properly secured and does not obscure your view ahead or to the sides, knowing your cargo does not restrict your access to emergency equipment.

Do the following to correct a drive-wheel braking skid: stop braking letting the rear wheels roll again and keep the rear wheels from sliding; counter-steer as a vehicle turns back on course, it tends to keep on turning. Unless you turn the steering wheel quickly the other way, you may find yourself skidding in the opposite direction.

 If possible, avoid using the brakes until your speed has dropped to about 20 mph, and gently return to the road.

Shut off the engine and take the key with you so someone else won't move the truck while you are under it.

It will take longer to stop, and it will be harder to turn without skidding, when the road is slippery. Wet roads can double stopping distance at any speed, reduce speed, and slow down gradually on a wet road. 

You need at least 4/32-inch tread depth in every major groove on front tires. No fabric should show through the tread or sidewall. There should be no cuts or other damage.

Strong winds make it difficult to stay in your lane. The problem is usually worse for lighter vehicles. This problem can be especially bad coming out of tunnels.

Poor weight balance can make vehicle handling unsafe. The cargo should be loaded so that it is balanced in the cargo area.

Explanation - For an e-route inspection: check the tires, wheels, and truck body for signs of heat whenever you stop during a trip.

You must review the inspection report made by the previous driver. Only if defects reported earlier have been certified as repaired or not needed to be repaired, should you sign the previous driver's report.

Because you cannot see everything behind your vehicle, backing is always dangerous. Avoid backing whenever you can. When you must back, here are a few simple safety rules: Start in the proper position, look at your path, use mirrors on both sides, back slowly, back and turn toward the driver's side whenever possible, and use a helper with clear hand signals whenever possible.

Tire problems include: too much or too little air pressure, bad wear, at least 4/32-inch tread depth on front tires, 2/32 inch on all other tires, no fabric should show through the tread or sidewall, cuts or other damage, tread separation, dual tires that come in contact with each other or parts of the vehicle, mismatched sizes, radial and bias-ply tires used together.