To help prevent a rig from rolling over, you should keep the weight of the cargo as close to the ground as possible when loading. You should also drive slowly around turns.

Before a trip, be sure to inspect all couplings. There should be no space between the upper and lower fifth wheel.

At speeds below 40 mph, you should allow at least one second of following distance for every 10 feet of your vehicle. Follow the same formula when traveling at faster speeds, then add one additional second to your following distance. Remember that larger vehicles require more space to stop than smaller vehicles.

If you are experiencing a trailer jackknife, you can help your tires regain traction by releasing the brakes. Using a trailer hand brake while experiencing a skid will only cause the skid to continue.

An empty combination vehicle will come to a complete stop more slowly than a fully-loaded vehicle. With less weight in a trailer, the stiff suspension springs and strong brakes will have lower traction than they would if the vehicle carried more weight.

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.

Rollovers can happen when a combination vehicle is turned too quickly. To help prevent the risk of rollover, it is important to keep the vehicle's center of gravity low by loading cargo as close to the ground as possible.

If you need to back your trailer but cannot back up in a straight path, you should back on a curved path toward the driver's side of the vehicle. This will allow you the best possible visibility while backing.

The emergency air line controls the emergency brakes on a combination vehicle. A loss of air pressure in the emergency line will cause the emergency trailer brakes to activate.

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.

If your trailer begins to drift while you are backing, you should correct the drift immediately by turning the top of the steering wheel in the direction of the drift.

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.

If your vehicle gets stuck on railroad tracks for any reason, you should immediately exit the vehicle and walk away from the tracks. Contact the proper emergency authorities.

If a parked trailer does not have spring brakes, wheel chocks should be used to prevent it from moving.

Air lines are sometimes color-coded to help drivers avoid mistakes when coupling glad hands. Typically, blue is used for service lines and red is used for emergency lines.

Be sure to test the trailer emergency brakes before beginning a trip. After ensuring that the trailer rolls freely, you can test the emergency brakes by pulling out the trailer air supply control, or placing it in the "emergency" position. Pull forward slightly with the tractor and make sure the trailer does not move.

If your trailer begins to skid, you should release the brakes to regain traction. The trailer will begin to straighten out once the wheels begin to grip the road again.

Making a sudden lane change can be dangerous while driving a combination vehicle. You can avoid the need to make a sudden lange change by looking down the road for upcoming obstacles that will require you to change lanes.

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

When making a turn, be sure to steer gently and smoothly. Making a quick turn while pulling trailers is dangerous and can increase the risk of the last trailer rolling over.