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.

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.

Correctly following the steps to couple and uncouple trailers is vital to safely operating a combination vehicle. Before backing your tractor under the trailer while coupling, make sure your trailer brakes are locked.

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.

Railroad-highway crossings may be difficult to cross when pulling a trailer with a low underneath clearance. In particular, both low-slung units and single-axle tractors pulling long trailers are especially challenging to drive over raised crossings.

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

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.

Before a trip, you should ensure that air reaches all air brakes on all trailers by opening up the rear emergency line and service line shut-off valves to listen for escaping air. Close both shut-off valves before beginning to drive.

While inspecting a coupling, you should go under the trailer and look into the back of the fifth wheel. Ensure that the fifth wheel jaws are secured around the shank of the kingpin.

On combination vehicles with air brakes, the tractor protection valve keeps air in the tractor or truck brake system, should the trailer develop a bad leak or break away from the tractor.

If your trailer starts to skid while you are braking, you should release the brakes and allow them to begin to regain traction. Once its wheels have regained their grip on the road, the trailer will begin to straighten out and follow the tractor.

Due to the "crack-the-whip" effect caused by rearward amplification, changing lanes too quickly in a combination vehicle can result in a rollover.

A trailer tends to swing around, potentially resulting in a trailer jackknife, if its wheels lock up.

In a combination vehicle with air brakes, the tractor protection valve keeps air in the tractor or truck brake system in the event of the trailer breaking away or developing a leak.

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.

Air pressure in the service air line is controlled by either the foot brake or trailer hand brake. The service air line is also known as the control line or signal line. This line is connected to relay valves, which allow the trailer brakes to be applied more quickly than would otherwise be possible.

Because the weight of cargo gives them a higher center of gravity, fully-loaded rigs are 10 times more likely to roll over in a crash than empty rigs.

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.

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.

The service air line carries air and is controlled by either the foot brake or trailer hand brake. The service air line is attached to relay valves, which allow the trailer brakes to be applied quickly.