MA CDL Air Brakes case studies
MA CDL Air Brakes · Put your knowledge to work in context.
The Massachusetts CDL Air Brakes knowledge test is the written exam a commercial driver takes to be certified on air brake systems. Passing it removes the air brakes restriction (L) from a Massachusetts commercial driver's license, which you need before you can legally operate a vehicle equipped with air brakes - most heavy trucks, tractor-trailers, and many buses. The MA CDL Air Brakes case studies are 5 cases and about 2,452 words.
1Primary Circuit Failure on a Loaded Tractor-Trailer
You are driving a 2019 tractor-trailer with a dual air brake system, loaded to about 72,000 lb GVW, on a two-lane state highway at 55 mph. The primary (rear) gauge has been steady at 115 psi.
497 words, about 2 min2Leak Test Numbers Out of Limits on a Combination Vehicle
At the end of the day you perform the air brake leak tests on your combination vehicle, a three-axle tractor with a tandem-axle van trailer. You build the system to 120 psi, shut off the engine, chock the wheels, release the parking brake, and let the pressure stabilize.
510 words, about 3 min3Brake Fade on a 6% Grade
You are descending a 6-mile, 6% grade on I-70 west of Denver in a 5-axle tractor-trailer loaded to 78,000 lb. The posted truck speed is 40 mph.
490 words, about 2 min4Push Rod Stroke and Slow Build-Up at Pre-Trip
You are doing a pre-trip on a 2014 single-axle tractor with a 53-foot trailer. The air system builds from 85 to 100 psi in 70 seconds at fast idle.
484 words, about 2 min5Low-Pressure Warning While Driving a Straight Truck
You are driving a 26,000 lb GVW straight truck with air brakes at 50 mph on a four-lane divided highway. The low-pressure warning light and buzzer activate.
471 words, about 2 min