In an air brake system, the air compressor governor controls when the air compressor pumps air into the air storage tanks.

Always be sure that you are driving in a manner that will allow your vehicle to come to a complete stop, if necessary, within the area of the road ahead that you are able to see.

On many vehicles, multi-speed rear axles and auxiliary transmissions are used to provide extra gears. They are usually controlled by a selector knob on the gearshift lever.

Except when parking briefly to perform necessary functions for vehicle operation (such as refueling), never park a vehicle carrying Division 1.1, 1.2, or 1.3 explosives within 300 feet of a bridge, tunnel, or building. Never park such a vehicle within five feet of the traveled portion of a road. Such vehicles should be parked only briefly.

During an inspection, there are a number of tire problems to check for and avoid. Look for air pressure that is too low or too high; excessive wear; cuts or other damage; tread separation; dual tires that come into contact with each other or other parts of the vehicle; mismatched tire sizes; radial and bias-ply tires used together; cut or cracked valve stems; and regrooved, recapped, or retreaded tires on the front wheels of a school bus.

Commercial vehicles should always carry the proper emergency equipment. Be sure your vehicle is equipped with at least one fire extinguisher; spare electrical fuses, unless the vehicle is equipped with circuit breakers; and warning devices for parked vehicles, such as warning triangles, fuses, or liquid burning flares.

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

A one-way check valve is required to be between an air compressor and the first main reservoir. This valve prevents air from escaping the system if the air compressor develops a leak.

On newer vehicles, the trailer air supply control is an eight-sided red knob. It's used to control the tractor protection valve.

Always downshift before entering a curve. Decreasing your speed before entering the curve will allow you to maintain better control over the vehicle throughout the curve.

When driving a tractor-trailer combination that is equipped with an Anti-Lock Braking System (ABS), you should brake in the same manner that you would if the vehicle was not equipped with ABS.

Low beam headlights allow you to see about 250 feet ahead of your vehicle. When driving at night, adjust your speed so that you will be able to stop in the distance illuminated by your headlights.

The controlled braking method for emergency stops involves applying the brakes as hard as you can without locking the wheels. Keep steering wheel movements small when braking in this way.

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.

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.

If you are driving a vehicle that is transporting Class 1 explosives and it is involved in an accident, you should warn others of the danger, keep bystanders away, and not allow smoking or open fires near the vehicle. Before separating the vehicles involved in the collision, remove all explosives and place them at least 200 feet away from the vehicles and any occupied buildings.

To avoid becoming an aggressive driver, begin a trip with realistic expectations of how long the trip will take, allowing extra time for traffic delays. Do not tailgate other vehicles. To avoid upsetting other drivers, do not drive slowly in the left lane and do not gesture at the drivers (even in seemingly minor ways, like shaking your head).

ABS is equipped in addition to a vehicle's normal braking system and it neither increases nor decreases the vehicle's braking capability. ABS activates during hard applications of the brake pedal in order to prevent wheels from locking up.

Before transporting hazardous materials, you should research any restrictions that may apply to the routes you plan to take.

In an air brake system, the application pressure gauge shows how much air pressure is being applied to the brakes. Not all vehicles with an air brake system have this gauge.