Due to their size, doubles and triples cannot be turned suddenly. They require extra care to avoid rollovers when turning.

Trailers built before 1975 are not required to have spring brakes. When parking a trailer without spring brakes, be sure to use wheel chocks to prevent the trailer from rolling.

You must drive smoothly to reduce the risk of jackknifing. To help make this possible, scan the road ahead of your vehicle to allow yourself plenty of time to maneuver in response to upcoming hazards.

Skids caused by acceleration can usually be corrected by taking your foot off of the accelerator. If you are on an especially slippery surface, you may also need to push the clutch in.

Combination vehicles need more space on the road than other commercial vehicles because they are longer and need more space to turn and stop. It is especially important to properly manage space when you are operating a combination vehicle.

An air compressor governor will stop the compressor from pumping air once the air tanks are at an air pressure level of 125 psi. This air pressure level is referred to as the "cut-out" level.

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

While driving, spring brakes are generally held in place by air pressure. If the air pressure gets low enough, the springs will activate the brakes.

When inspecting a vehicle's brakes, you should make sure the shoes and pads do not have oil, grease, or brake fluid on them.

When inspecting a vehicle with power steering, you should inspect the hoses, pumps, and fluid levels. Specifically check the hoses for leaks.

In work zones, you should observe posted speed limits. Slow down if road or weather conditions are poor, and slow down even further if workers are near the roadway.

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.

Double and triple combinations must be driven very smoothly to avoid jackknifing and rolling over. To aid in smooth driving, you should look far ahead of your vehicle so that you have plenty of time to make appropriate maneuvers when reacting to hazards.

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.

When coupling a triple trailer rig, you should first couple the trailer immediately behind the cab. Connect the second and third converter dollies and trailers in order.

To send air to the emergency (supply) lines, a driver can push in the trailer air supply control knob. The knob is red and eight-sided.

Most heavy vehicles with manual transmissions require double clutching to change gears. A driver should release the accelerator, push in the clutch, and shift into neutral at the same time. After releasing the clutch and allowing the vehicle to change to the necessary speed, the driver should push in the clutch, shift gears, then simultaneously release the clutch and accelerate.

The function of an Anti-Lock Braking System (ABS) is to prevent a vehicle's wheels from locking up during hard braking.

If you must drive in fog, you should use your low beam headlights and fog lights, even during the day.

After coupling trailers, be sure to check the air brakes. If air does not flow all the way to the back each brake line, the brakes will not work.