Georgia CDL DMV Combination 2

Bobtail tractors are tractors that are not attached to any semitrailers. When operating a bobtail, you should be aware that stopping can be difficult and that it will take a longer distance to bring the bobtail to a complete stop than it would a tractor attached to a loaded semitrailer.

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.

If you are operating a vehicle built before 1998 and are unsure if the trailer has an Anti-Lock Braking System (ABS), you can check under the trailer for wheel speed sensors coming from the back of the brakes.

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.

Never use the trailer hand valve while operating your vehicle. Using the trailer hand valve while driving can cause your trailer to skid.

The service line, also called the control line or signal line, carries air to the trailer brakes and is controlled by the foot brake or trailer hand brake.

Triple combination trailers are most vulnerable to the "crack-the-whip" effect.

When backing with a trailer, turn the top of the steering wheel in the direction opposite of where you want to go. Once the trailer begins turning, you should then switch the direction of the steering wheel to follow the trailer.

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

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

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.

Rollovers happen when an operator turns too fast. Drivers should be sure to slow down before entering turns and curves, especially when transporting a fully-loaded rig.

Tractor protection controls in older vehicles may be operated by levers instead of knobs. If an air supply control is set in its "normal" position, it is properly set for you to pull a trailer.

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.

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.

Combination vehicles have two air lines: a service line and an emergency line.

The trailer hand valve should not be used for parking. This could cause all of the air to leak out of the braking system, resulting in the brakes releasing. Instead, use the parking brake.

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

When connecting a converter dolly to a second or third trailer, the trailer height should be correct. It should be slightly lower than the center of the fifth wheel.

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.