ME CDL Air Brakes case studies
ME CDL Air Brakes · Put your knowledge to work in context.
The Maine CDL Air Brakes knowledge test is the written portion of the commercial licensing process for drivers who will operate vehicles equipped with air brakes, including many Class A and Class B trucks and most commercial buses. Maine requires this knowledge test in addition to the general CDL tests when the vehicle you drive, or the endorsement you add, involves air brakes; the air brake restriction applies to drivers who have not passed it. The ME CDL Air Brakes case studies are 5 cases and about 2,645 words.
1Leak Test Failure Before Dispatch
You are assigned a 26,000-lb GVWR straight truck with a dual-circuit air system and no trailer. Before departure, you build pressure to governor cut-out at 125 psi and shut the engine off.
461 words, about 2 min2Air Loss on a 6 Percent Downgrade
You are driving a loaded 80,000-lb tractor-semitrailer down a 6 percent grade that runs 4 miles. Speed is 45 mph in 7th gear; the engine brake is on high and the service brakes are cool.
569 words, about 3 min3Automatic Slack Adjuster Keeps Going Out
Three weeks after a rear brake reline on a 2019 tandem-axle tractor, the driver reports a hot smell and drag at the right rear inner wheel. At 90 psi with the spring brakes released, you measure 2 3/4 inches of pushrod travel on that wheel.
522 words, about 3 min4Retarder, ABS, and Low-Traction Downgrade
You are descending a 5-mile, 5 percent grade in a 5-axle tractor-semitrailer loaded to 60,000 lb. The temperature is 28°F with freezing rain, and patches of the right lane are icy.
564 words, about 3 min5Roadside Inspection: Warning Device and Brake Stroke
At a Maine roadside inspection, a 33,000-lb GVWR straight truck with air brakes is pulled in. The driver holds a valid Class B CDL with no air-brake restriction and has a current medical card.
529 words, about 3 min