Oklahoma CDL Permit Test - Double

Because doubles and triples are more vulnerable than singles to jackknifing and rolling over, drivers should look far ahead of their vehicles so they can react to hazards well in advance and slow down or change lanes gradually.

An Anti-Lock Braking System (ABS) helps prevent wheels from locking up during a hard application of brakes.

Landing gear, or trailer supports, should always be completely raised before a vehicle is driven. Landing gear that is not entirely raised could catch on railroad tracks or other hazards on the roadway.

Backing a CMV is always dangerous due to limited visibility, so using a helper to monitor your blind spots is encouraged whenever possible.

If you are not certain that your vehicle will fit under overhead objects, you should slow down and take a different route, if possible.

Leaks in an exhaust system are extremely dangerous because they may allow toxic fumes into the cab or sleeper berth, endangering drivers and passengers.

Spring brakes do not work on all axles. If your vehicle's spring brakes activate due to low pressure in an air brake system, your vehicle will need a longer distance to stop than usual, especially if you are carrying a heavy load.