One good rule says you need at least one second for each 10 feet of vehicle length at speeds below 40 mph. At greater speeds, you must add 1 second for safety.

The convex mirrors are located below the outside flat mirrors. They are used to monitor the left and right sides at a wide angle. They provide a view of traffic and clearances. These mirrors present a view of people and objects that does not accurately reflect their size and distance.

Commercial vehicles are often wide and take up most of a lane. Safe drivers will manage what little space they have. You can do this by keeping your vehicle centered in your lane and avoid driving alongside others.

To prevent trailers from rolling over, you must steer gently and go slowly around corners, on ramps, off ramps, and curves. A safe speed on a curve for a straight truck or a single trailer combination vehicle may be too fast for a set of doubles or triples.

Check your mirrors: Before you change lanes to make sure there is enough room. After you have signaled, to check that no one has moved into your blind spot. Right after you start the lane change, to doublecheck that your path is clear. After you complete the lane change.

Shut-off valves at rear of trailers, in service and emergency lines. Rear of front trailers: open. Rear of last trailer: closed.

Slow down and place transmission in a low gear. Gently put on the brakes. This presses linings against brake drums or discs and keeps mud, silt, sand, and water from getting in.

To inspect a double or triple, first inspect it just as you would inspect any combination vehicle. Then check that the shut-off valves are open on all trailers but the last trailer. Check each converter dolly to be sure that the pintle hook is properly latched.

Doubles and triples must be driven very smoothly to avoid rollover or jackknife. Therefore, look far ahead so you can slow down or change lanes gradually when necessary

Make sure trailer brakes are locked and/or wheels chocked.

Rearward amplification causes the crack-the-whip effect. Triples have a rearward amplification of 3.5 meaning you can roll the last trailer of triples 3.5 times as easily as a five-axle tractor. A Double has a reward amplification of 2 being twice as likely to roll over as a five-axel trailer.

The use of brakes on a long and/or steep downgrade is only a supplement to the braking effect of the engine. The following are the proper braking techniques: Apply the brakes just hard enough to feel a definite slowdown. When your speed has been reduced to approximately five mph below your "safe" speed, release the brakes. When your speed has increased to your "safe" speed, repeat.

Converter dollies often do not have spring brakes.

Doubles and triples must be driven very smoothly to avoid rollover or jackknife. Therefore, look far ahead so you can slow down or change lanes gradually when necessary.

Truck tractors with air brakes built on or after March 1, 1997 require ABS, and other air brake vehicles such as trucks, buses, trailers, and converter dollies built on or after March 1, 1998 require ABS.

There are more things to inspect on a double or triple combination vehicle than on a single vehicle. Many of these items are simply more of what you would find on a single vehicle. For example, tires, wheels, lights, reflectors, etc. However, there are also some new things to check.

Most good drivers look at least 12 to 15 seconds ahead. That means looking ahead the distance you will travel in 12 to 15 seconds. At lower speeds, that's about one block. At highway speeds it's about a quarter of a mile.

Due to rearward amplification a double is twice as likely, and a triple is 3.5 times more likely to roll over than a five-axel trailer.

A converter gear on a dolly is a coupling device of one or two axles and a fifth wheel by which a semitrailer can be coupled to the rear of a tractor trailer combination forming a double bottom rig.

Lower dolly landing gear.