The trailer service air line is also referred to as the control line or signal line.

Remaining in neutral for too long when shifting gears may make it difficult to put the vehicle into the next gear.

The only effective way to deal with drowsiness while driving is to stop and sleep. Caffeine or other stimulant drugs may help you stay awake, but they will not keep you alert. You will likely end up being even more tired when the artificial stimulants begin to wear off.

Driving at excessive speeds is a major cause of fatal crashes. Never drive above the posted maximum speed limit and adjust your speed to fit conditions.

You should test the tractor protection valve by allowing the air supply to properly charge, turning off the engine, then releasing air from the system by pressing the brake pedal several times. The tractor protection valve should move into its emergency position when psi drops to an unsafe level.

Hazardous materials warning placards must be used on all four sides of a vehicle transporting hazardous materials.

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.

Be sure to check the tightness of the belts in your engine compartment. Loose belts will not turn the water pump and/or fan properly, which can lead the engine overheating.

Parking brakes should always be checked before driving as a part of your pre-trip inspection. If the parking brakes do not hold, the vehicle is faulty and should be fixed.

When hazardous materials placards are required, they must be placed on all four sides of the transporting vehicle.

As a precaution, you should always approach a railroad crossing under the assumption that a train is coming. Do not rely only on signals or your hearing to indicate that a train is approaching.

Defects in an exhaust system are very dangerous because they can cause poisonous fumes to enter the cab or sleeper berth.

Shippers must place diamond-shaped hazard warning labels on most packages of hazardous materials. If the label won't fit on the package, it can be placed on a tag that is securely attached to the package.

All trailers and converter dollies manufactured on or after March 1, 1998 must be equipped with Anti-Lock Braking Systems (ABS).

To avoid being blinded by the lights of an oncoming vehicle at night, you can glance to the right edge of the road until the vehicle has passed.

A trailer may swing out and strike other vehicles if its wheels lock up. This is especially likely with lightly-loaded trailers.

Federal and state laws require that CMV drivers inspect their vehicles before every trip.

Driving tank vehicles requires special care because they have high centers of gravity. Drivers should be particularly aware of their speeds when operating in turns and curves

The average driver has a reaction time of between three-quarters of a second and one second.

Before a trip, ensure that air in the air brake system reaches all trailers. Do this by waiting for air pressure to build, then sending air to both the emergency and service lines and opening the shut-off valves on the rear of the last trailer. If air escapes from the shut-off valves in the rear of the combination, the air is being supplied to the entire vehicle.