Free CDL Practice Test (20 Questions) | ExamsLib

Question 1

What is the minimum age to obtain a Commercial Learner's Permit under federal rules?

Accepted Answer

18

Answer

16

Answer

21

Answer

25

Question 2

A driver is convicted of a DUI while operating their personal vehicle, not a commercial motor vehicle. Does this affect their CDL?

Accepted Answer

Yes, a DUI conviction disqualifies a CDL regardless of which vehicle was involved

Answer

No, only CMV-related DUI convictions matter

Answer

Only if the driver was hauling hazardous materials

Answer

Only if the driver was under 21

Question 3

A driver holding only a CLP is asked to haul a load containing hazardous materials. What is the correct response?

Accepted Answer

Decline, since CLP holders may not transport hazardous materials under any circumstances

Answer

Accept, since P and S endorsements allow hazmat hauling

Answer

Accept, but only with a supervising driver present

Answer

Accept, if the load is under 1,000 gallons

Question 4

Why should air tanks be drained regularly?

Accepted Answer

To remove moisture and oil that can collect in the tanks and damage the system

Answer

To reduce vehicle weight before weigh stations

Answer

To increase air pressure artificially

Answer

Draining tanks is not necessary in modern vehicles

Question 5

What should a driver do if the low air pressure warning activates while driving?

Accepted Answer

Stop safely as soon as possible and address the air loss before continuing

Answer

Continue driving normally since the warning is only precautionary

Answer

Increase speed to reach the next stop faster

Answer

Turn off the warning device and continue

Question 6

Why do air brake systems generally use compressed air instead of hydraulic fluid on heavy commercial vehicles?

Accepted Answer

Air brake systems can supply consistent braking force across heavier vehicles and multiple trailer units more effectively

Answer

Air is more expensive than brake fluid, so it signals a higher-quality vehicle

Answer

Hydraulic brakes cannot be used on any vehicle over 10,000 pounds

Answer

Air brakes require no maintenance at all

Question 7

What should a driver do to verify the fifth wheel connection is secure during a pre-trip or coupling check?

Accepted Answer

Pull the tractor forward gently against the trailer brakes to test that the coupling holds

Answer

Only look at the connection visually from a distance

Answer

Assume it is secure if the vehicle was coupled the day before

Answer

Rely solely on a dashboard warning light

Question 8

What blood alcohol concentration (BAC) is the disqualifying threshold for a driver operating a commercial motor vehicle under federal rules?

Accepted Answer

0.04

Answer

0.08

Answer

0.02

Answer

0.10

Question 9

What is the purpose of the spring brakes (parking brake) found on most air brake vehicles?

Accepted Answer

To hold the vehicle in place when parked and to apply emergency braking if air pressure is lost

Answer

To provide extra acceleration power

Answer

To cool the brake drums

Answer

To measure tire pressure

Question 10

What is a 'combination vehicle' in the context of CDL classifications?

Accepted Answer

A tractor connected to one or more trailers

Answer

A single straight truck with no trailer

Answer

A passenger bus only

Answer

A pickup truck towing a small utility trailer under 10,000 pounds