A safety relief valve is installed in the first tank the air compressor pumps air to. The safety valve protects the tank and the rest of the system from too much pressure. The valve is usually set to open automatically at 150 psi.

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 will lose your CDL for at least one year for a first offense for: Driving a CMV if your blood alcohol concentration is .04% or higher or driving a CMV under the influence of alcohol.

Vehicles must be equipped with emergency equipment. Look for: fire extinguisher(s), spare electrical fuses (unless equipped with circuit breakers), and warning devices for parked vehicles.

If an oncoming driver has drifted into your lane, a move to your right is best. If that driver realizes what has happened, the natural response will be to return to his or her own lane.

Some vehicles, by their nature, are slow and some of these will have the "slow moving vehicle" symbol to warn you. This is a red triangle with an orange center.

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

To test the parking brakes: Fasten safety belt, set parking brake, release trailer parking brake, Place vehicle into a low gear, gently pull forward against parking brake to make sure the parking brake holds. If it doesn't hold vehicle, it is faulty; get it fixed.

Know escape ramp locations on your route. Signs show drivers where ramp are located. Escape ramps save lives, equipment and cargo.

Never remove the radiator cap or any part of the pressurized system until the system has cooled. Steam and boiling water can spray under pressure and cause severe burns.

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.

Under-inflated tires, loose fuel connections, and electrical short-circuits can all lead to fires.

Enforcement of the HOS (Hours of Service) rules is generally handled by DOT officers of their respective states, although any ordinary police officer may inspect a driver's log book.

One good rule says 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.

Backing off just means you slow down, if the vehicle was in a blind spot this change in speed should force it out of the blind spot.

Under-loaded front axles can make the steering axle weight too light to steer safely.

A skid happens whenever the tires lose their grip on the road. Most serious skids result from driving too fast for road conditions. Drivers who adjust their driving to conditions don't overaccelerate and don't have to over-brake or oversteer from too much speed

Applying the brakes causes friction to slow the vehicle, the faster it is moving, or the heavier it is the more heat that must be absorbed to stop the vehicle.

You can regain control by releasing the accelerator and pushing in the clutch. This will slow your vehicle and let the wheels turn freely. If the vehicle is hydroplaning, do not use the brakes to slow down.

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.

Here are some signs of slippery roads: shaded areas, bridges, melting Ice, black Ice makes the road look wet, and just after rain begins.

It is illegal to operate a CMV if your blood alcohol concentration (BAC) is .04% or more. If you operate a CMV, you shall be deemed to have given your consent to alcohol testing.

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

Axle Weight is the weight transmitted to the ground by one axle or one set of axles

Inspect the cargo and its securing devices within the first 50 miles after beginning a trip. Make any adjustments needed.

Your best hope is an escape ramp. If there is one, there will be signs telling you about it. Use it. Ramps are usually located a few miles from the top of the downgrade. Escape ramps save lives, equipment and cargo.

Because of slow acceleration and the space large vehicles require, you may need a much larger gap to enter traffic than you would in a car. Acceleration varies with the load, allow more room if your vehicle is heavily loaded. Before you start across a road, make sure you can get all the way across before traffic reaches you.

You cannot inspect sealed loads, but you should check that you don't exceed gross weight and axle weight limits.

If you look sleepy, or you just feel sleepy, stop driving! You are in a very dangerous condition. The only safe cure is to sleep.

Don't roll back when you start. You may hit someone behind you. If you have a manual transmission vehicle, partly engage the clutch before you take your right foot off the brake. Put on the parking brake whenever necessary to keep from rolling back. Release the parking brake only when you have applied enough engine power to keep from rolling back

Front-end header boards ("headache racks") protect you from your cargo in case of a crash or emergency stop. The front-end structure should block the forward movement of any cargo you carry.

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.

There are two basic reasons for covering cargo: to protect people from spilled cargo, and to protect the cargo from weather. Spill protection is a safety requirement in many states. Be familiar with the laws in the states you drive in.

On packed snow, reduce speed by a half, or more. If the surface is icy, reduce speed to a crawl and stop driving as soon as you can safely do so.

A full tank of dense liquid (such as some acids) may exceed legal weight limits. The amount of liquid to load into a tank depends on: the amount the liquid will expand in transit, the weight of the liquid, legal weight limits.

Check wheel bearing seals to make sure they are not leaking.

Some drivers make the mistake of always using low beams. This seriously cuts down on their ability to see ahead. 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.

Your horn can let others know you're there. It can help to avoid a crash. Use your horn when needed. However, it can startle others and could be dangerous when used unnecessarily.

Hanging meat can be a very unstable load with a high center of gravity, particular caution is needed on sharp curves such as off ramps and on ramps. Livestock can move around in a trailer, causing unsafe handling, and special care is necessary because livestock can lean on curves.

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

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

You can drive a vehicle that carries hazardous materials if it does not require placards. If it requires placards, you cannot drive it unless your driver license has the hazardous materials endorsement.

Cargo should have at least one tie-down for each ten feet of cargo. Make sure you have enough tiedowns to meet this need. For a 20-foot load you would need at least 2 tie downs.

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.

Tar in the road pavement frequently rises to the surface in very hot weather. Spots where tar "bleeds" to the surface are very slippery.

Perception Distance + Reaction Distance + Brake Lag Distance + Braking Distance = Total Stopping Distance.

Pre-trip is an inspection before you leave, en-route occurs during your daily travel, and post-trip happens at the end of your day.

Brake pads should not be dangerously this or have fluid on them, and a missing leaf in the leaf spring suspension is very dangerous.

At 55 mph, your vehicle will travel a minimum of 419 feet.

Most good drivers look at least 12 to 15 seconds ahead. That means looking ahead the distance you will travel in 12 to 15 seconds. At lower speeds, that's about one block. At highway speeds it's about a quarter of a mile.