Commercial Driver's License Flashcards

When backing a tractor-trailer, a driver should primarily use which mirrors?

Answer: Both side mirrors and get out to check when uncertain

Drivers should use both side mirrors and physically check the area (get out and look) when uncertain to ensure safety while backing.

What is the maximum allowable blood alcohol content (BAC) for CDL holders operating a commercial motor vehicle?

Answer: 0.04%

The legal BAC limit for CDL drivers operating a CMV is 0.04%, half the standard limit for non-commercial drivers.

Which of the following describes a 'runaway truck ramp' and when it should be used?

Answer: An escape ramp used when brakes fail on a downgrade

A runaway truck ramp is an emergency escape route filled with sand or gravel designed to stop a truck with failed brakes on a steep downgrade.

What is the correct procedure for using the spring brakes when parking a CMV?

Answer: Chock the wheels and apply the parking brake

Drivers should chock the wheels and fully apply the parking (spring) brake to prevent the vehicle from rolling while parked.

Under federal hours-of-service rules that apply in Pennsylvania, property-carrying CDL drivers may not drive after being on duty for how many cumulative hours in 8 days?

Answer: 70 hours

Under the 8-day/70-hour rule, property-carrying drivers may not drive after accumulating 70 on-duty hours in any 8 consecutive days.

A CDL driver approaching a railroad crossing with no signals or gates must stop if the vehicle is carrying:

Answer: Chlorine, even in small amounts not requiring placards

Vehicles carrying any quantity of chlorine must always stop at railroad crossings regardless of whether placards or signals are present.

What is the primary purpose of retarder systems (Jake brakes) on commercial vehicles?

Answer: To slow the vehicle and reduce wear on service brakes

Retarders help slow the vehicle on downgrades and in traffic, reducing heat and wear on the service brakes.