Never unlock the pintle hook with the dolly still under the rear trailer. This could cause the dolly tow bar to fly up, possibly causing serious injury.

If a heavy load prevents your vehicle from keeping up with the speed of other traffic, you should stay in the right lane.

If you must drive in fog, you should use your low beam headlights.

When driving, you should continually scan the road for possible hazards. Form plans about what you will do if the hazards develop into emergencies.

Most hydraulic brake failures occur for one of two reasons. A first likely cause of brake failure is that the brakes have been overused on a downgrade, causing them to fade. The second likely cause is that there has been a loss of hydraulic pressure in the braking system. Brakes kept in good condition will rarely fail, but you should know which steps to take in case they do.

For safe driving, it is essential that you maintain cushions of space on all sides of your vehicle. This helps to ensure that you will have time to take appropriate action if a problem arises.

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.

While driving downhill, you should hold down the brake pedal until your vehicle reaches a speed 5 mph below your safe speed, then release the brake pedal. Repeat this process.

When doing a pre-trip inspection during the winter, you should pay extra attention to the coolant level and amount of antifreeze; the defrosting and heating equipment; the wiper blades and windshield washer; the tires and tire chains; the lights and reflectors; the windows and mirrors; the hand holds, steps, and deck plates; the radiator shuttles and winterfront; and exhaust system.

ABS is equipped in addition to a vehicle's normal braking system and it neither increases nor decreases the vehicle's braking capability. ABS activates during hard applications of the brake pedal in order to prevent wheels from locking up.

Before coupling together a tractor and a trailer, you should make sure the trailer is at the proper height. If the trailer is too low, the trailer nose may be damaged. If the trailer is too high, it may not be able to couple correctly.

A converter gear on a dolly is a coupling device with one or two axles and a fifth wheel, onto which a semi-trailer can be coupled to the rear of a tractor-trailer combination.

Driving at excessive speeds is a major cause of fatal crashes. Never drive above the posted maximum speed limit and adjust your speed to fit conditions.

Many large vehicles have curved, convex mirrors. Convex mirrors allow drivers to see a wider area than flat mirrors. However, they also make objects seem smaller and farther away than they really are.

In an air brake system, the air compressor governor controls when the air compressor pumps air into the air storage tanks.

There are two indicators that determine when you need to shift into a higher gear. One indicator is the engine speed (rpm). You should read your vehicle's manual to learn its rpm range and shift up when you reach the top of that range. The other indicator is road speed (mph). You should learn which speeds each gear can accommodate, then keep an eye on the speedometer and shift up as needed.

Using a trailer hand valve while driving could create a skid. The trailer hand valve should only be used when testing the trailer brakes.

After you start the engine, keep an eye on the gauges. Oil pressure should rise to a normal level within a few seconds of the engine being started.

If your brakes fail on a downgrade, you will have to look outside your vehicle for a way to stop. Using an escape ramp is the safest way to stop your vehicle.

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