Illinois CDL Air Brakes case studies
Illinois CDL Air Brakes · Put your knowledge to work in context.
The Illinois CDL Air Brakes knowledge test is the written endorsement exam a commercial driver must pass before operating a commercial motor vehicle equipped with air brakes. Illinois administers CDL requirements, training, and testing through the Secretary of State's office, and the air brakes test is one of the knowledge tests tied to that process. The Illinois CDL Air Brakes case studies are 5 cases and about 4,214 words.
1Slow Build at the Shop Gate
Your company's 2015 straight truck (26,000 lb GVWR, air brakes on both axles, single vehicle, no trailer) has failed the same pre-trip test three mornings running. At 1,200 rpm fast idle the system climbs from 85 to 100 psi in 70 seconds; the shop manual allows no more than 45 seconds for that range.
957 words, about 5 min2Primary Circuit Failure at Highway Speed
Driver Ruiz is southbound on a two-lane state route at 55 mph in a 2017 tri-axle dump truck (66,000 lb, air brakes on all three axles, no trailer) loaded with gravel. Coming up on a reduced-speed zone he applies the brakes and hears a sharp hiss.
815 words, about 4 min3Grading the Pre-Trip Air Loss Numbers
An owner-operator is doing the air-brake portion of the Illinois pre-trip on a loaded 5-axle tractor-trailer (3 tractor axles, 2 trailer axles) before a run to Chicago. The system is charged to 125 psi with the governor cut out.
805 words, about 4 min4Six Percent, Seven Miles, and a Light Foot
A driver takes a loaded 5-axle tanker (80,000 lb) down a signed 6% grade, 7 miles long, at night in a 55 mph zone. At the top he shifts into 7th gear, which holds about 35 mph on the engine brake alone, but he leaves his foot lightly on the brake pedal the whole way because the engine brake is loud and he does not want to wake the town below.
827 words, about 4 min5Ruptured Chamber on a Two-Lane Bridge Approach
A driver is on a two-lane state route at 55 mph in a 33,000 lb three-axle straight truck with air brakes, approaching a curve and a short bridge, when he brakes for the curve. He hears a loud pop-hiss from the right side and the truck pulls left; the low-air buzzer sounds.
810 words, about 4 min