District Of Columbia cdl Class B Knowledge Test - 2
Number of questions: 50
Passing score: 80%
Acceptable number of errors: 10
This license is required for driving a single vehicle with a GVWR of more than 26,001 pounds, and a trailer not to exceed 10,000 pounds gross vehicle weight rating, or a vehicle designed to transport 24 or more people (including the driver). To receive this license, applicants must pass a 50-question test. To pass, applicants must answer 40 questions correctly. Each question has four possible answer choices. Test questions come from the Washington D.C. Commercial Driver License Manual. Questions come from chapters covering: Introduction, Driving Safely, Transporting Cargo Safely, Air Brakes (if applicable), Pre-Trip Vehicle Inspection Test, Basic Vehicle Control Skills Test and On-Road Driving.. Endorsements that may be used with a Class B CDL are: Hazardous materials, Tank, Passenger, HazMat and Tank, Air Brakes and School bus.
To DMV Handbooks3. In a vehicle with dual parking control valves, once air pressure is lost and the spring brakes come on:
You will be unable to move the vehicle.
A separate air tank can be used to release the spring brakes for a short period of time.
You can use the spring brakes to continue driving normally.
The air tanks will automatically refill to a safe air pressure level.