When backing up to couple a trailer, you should position the tractor directly in front of the trailer. Trying to couple while backing at an angle could cause the trailer to move and the landing gear to break.

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.

Shut-off valves are used in air supply lines to control the passage of air from one trailer to another. The rear shut-off valve should always be closed to prevent air from leaving the braking system.

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.

Air tanks should be drained daily to remove water and oil buildup. An excess of oil and water in the air tanks can interfere with proper brake function.

Knowing proper coupling and uncoupling technique is fundamental to the safe operation of combination vehicles. Improper coupling can be very dangerous.

To test the trailer service brakes, you should first ensure that the braking system has a normal air pressure level, then release the parking brake. You should then move the vehicle forward slowly and apply the brakes with the hand control. If the trailer service brakes are working properly, you will feel the brakes activate.

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 permit you the best possible visibility while backing.

When driving a tractor-trailer combination equipped with an Anti-Lock Braking System (ABS), you should brake in the same manner that you would in a vehicle without ABS.

The trailer hand valve works the trailer brakes but should only be used when testing them. Using it while driving could create a skid. 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.

To lower the risk of a rollover, load your cargo as closely to the ground as possible. To further reduce this risk, take curves and corners slowly.

Before coupling together a tractor and a trailer, you should make sure the trailer is at the proper height. If the trailer is too low, the trailer nose may be damaged. If the trailer is too high, it may not be able to couple correctly.

If a trailer begins to jackknife, you should release the brakes and allow the trailer wheels to regain traction with the road. Do not apply the trailer hand brake to attempt to straighten out the rig because the application of brakes is what caused the wheels to lock in the first place.

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

An empty trailer will require a longer stopping distance than a loaded trailer. Additionally, a trailer is most likely to swing out and strike other vehicles when it is lightly loaded or empty.

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.

When a vehicle goes around a corner, the rear wheels follow a different path than the front wheels. This is called off-tracking. This effect is especially pronounced on vehicles with trailers.

When coupling, be sure to couple the proper glad hands. When glad hands are connected, the seals should be pressed together at a 90-degree angle.

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.

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.