Florida CDL DMV Combination 2

Driving a combination vehicle usually requires more skill than driving a single vehicle. Combination vehicles are generally longer and heavier than single commercial vehicles.

A rollover happens as a result of a driver taking a turn at too high a speed. Be sure to take turns and curves safely and slowly.

On newer vehicles, the trailer air supply control is an eight-sided red knob. It's used to control the tractor protection valve.

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.

Correctly following the steps to couple and uncouple trailers is vital to safely operating a combination vehicle. After connecting the air lines to the trailer while coupling, you should supply air to the trailer.

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

The emergency air line (also known as the supply line) has two functions. The first is to supply air to the trailer air tanks on a combination vehicle, and the second is to control the emergency brakes.

When a vehicle goes around a corner, the rear wheels follow a different path than the front wheels. This is known as off-tracking, or "cheating."

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.

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.

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.

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

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.

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

Failure to keep the fifth wheel plate properly lubricated can create friction between the tractor and trailer, causing steering problems.

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.

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.

If your trailer goes off course while you are backing, you should pull your truck forward and reposition your vehicle as needed before continuing to back up.

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

When positioning trailers in a combination, the most heavily-loaded trailer should be the closest to the tractor. The lightest trailer should be positioned in the rear.