MCQ Questions and Answers Flashcards

What is the 'crack-the-whip' effect and which vehicles are most susceptible?

Answer: A phenomenon where the rear of a multi-trailer combination swings outward more than the front during lane changes

The crack-the-whip effect occurs in multi-trailer combinations (doubles/triples) where small steering inputs cause amplified trailer movement at the rear, making the last trailer swing widely.

What is the difference between controlled braking and stab braking?

Answer: Controlled braking applies steady firm pressure without locking wheels; stab braking alternates between full application and release

Controlled braking maintains firm, steady brake pressure just short of wheel lockup, while stab braking alternates between full brake application (until wheels lock) and full release to maintain some steering.

Under what conditions is a CMV required to stop at a railroad crossing?

Answer: Buses, hazmat vehicles, and certain other CMVs must stop at all railroad crossings regardless of signals

Federal regulations require certain CMVs to stop at all railroad crossings: buses carrying passengers, vehicles carrying hazardous materials, and cargo tank vehicles (loaded or empty).

What is the purpose of the S-cam in a CMV drum brake system?

Answer: To push the brake shoes outward against the drum when the brakes are applied

The S-cam is an S-shaped cam that rotates when the slack adjuster is pushed by the brake chamber, forcing the brake shoes outward against the inside of the brake drum to create friction.

What is meant by 'off-tracking' in CMV driving?

Answer: The tendency of a trailer's rear wheels to follow a shorter path than the tractor's front wheels during turns

Off-tracking occurs when the trailer's rear wheels track a tighter (shorter radius) path than the tractor's front wheels during a turn, requiring the driver to swing wider to prevent running over curbs or obstacles.

What emergency equipment must be in a CMV carrying Division 1.1 explosives?

Answer: Standard equipment plus a properly rated fire extinguisher of at least 10 B:C rating

Vehicles carrying Division 1.1 explosives must carry a fire extinguisher with a rating of at least 10 B:C, in addition to the standard emergency equipment required for all CMVs.