When pressing the brake pedal in a vehicle with S-cam brakes, air will enter the brake chambers. The added air pressure will push out the rods and move slack adjusters, twisting the brake camshafts.

If you think the road surface may be becoming icy but you are not certain, you can open your window and feel the front of the side mirror, mirror support, or antenna. If ice has formed on any of these items, the road is likely becoming icy as well.

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.

If you discover a cargo leak while transporting hazardous materials, use the shipping papers, label, or package location to identify which materials are involved. Do not try to touch or smell the leaking materials to determine what they are because doing so could result in injury or death.

The safety relief valve in an air brake system releases air if necessary to prevent pressure in the system from becoming too high. If the valve starts releasing air, there is something wrong. Have a mechanic fix the problem.

Never remove the radiator cap or any part of the pressurized cooling system until it has cooled. Opening the cap while the system is too hot could release steam and boiling water that could severely burn you. If the radiator cap is cool to the touch, the system is likely cool enough for you to open the cap.

If you are twice convicted of violating any state law regarding hand-held mobile phone use, your CDL will be disqualified. Consequences will become more severe with subsequent violations.

When driving in reverse, it is always recommended that a driver backs their vehicle toward its left side. This will allow the driver the best possible view of the rear of their vehicle.

An Anti-Lock Braking System (ABS) helps prevent wheel lockup during hard braking. If ABS detects impending lockup, it reduces braking pressure to a safe level.

A person attending a placarded vehicle must be awake inside the vehicle or otherwise within 100 feet of the vehicle; know the hazards associated with the materials; know what to do in an emergency; and be able and authorized to move the tank if necessary.

Eating heavy foods before driving or keeping the temperature in a cab too high can cause a driver to become drowsy while behind the wheel. Exercising and maintaining a healthy diet will help a driver to stay alert while driving.

Never use the trailer hand valve while parking because doing so may release the air pressure from the braking system, releasing the brakes that are holding the vehicle in place. Instead, use the parking brake or wheel chocks.

Trailers built before 1975 are not required to have spring brakes. When parking a trailer without spring brakes, be sure to use wheel chocks to prevent the trailer from rolling.

When inspecting a vehicle equipped with power steering, you should inspect the hoses, pumps, and fluid levels. Specifically check the hoses for leaks.

If your CMV gets stuck on railroad tracks, you should immediately leave the vehicle and get away from the tracks. Check the signposts or signal housing at the crossing for emergency contact information and call 911, or another appropriate emergency number.

To ensure that you can see as well as possible, don't wear sunglasses when driving at night. If you wear eyeglasses, make sure they are clean and unscratched. Make sure you are rested and alert before driving at night.

Before driving, be sure to check the tank's body for dents or cracks. You should also check around and under the vehicle for signs of leaks. It is a crime to carry gases or liquids in a leaking tank.

If a heavy load prevents your vehicle from keeping up with the speed of other traffic, you should stay in the right lane.

During a pre-trip inspection, you should verify that the air pressure is neither too low nor too high in any of your tires.

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.