OR CDL Air Brakes case studies
OR CDL Air Brakes · Put your knowledge to work in context.
The Oregon CDL Air Brakes Knowledge Test is the written endorsement exam a commercial driver must pass before operating a vehicle equipped with air brakes. Oregon requires the air brakes restriction to be removed from a CDL before a driver may legally operate air-brake-equipped trucks, buses, and combinations, so this test matters for anyone moving into heavy vehicles, school buses, or tractor-trailer work. The exam is delivered in multiple-choice format on a computer at an Oregon DMV office. Content follows the air brake chapter of the Oregon CDL manual: system components and how they work together, the dual-circuit system and its safety features, the pre-trip inspection sequence, the three official system checks (leakage rates, low pressure warning, spring brake test), driving techniques such as proper braking on grades, and emergency procedures when pressure is lost. The OR CDL Air Brakes case studies are 5 cases and about 2,212 words.
1Primary Circuit Rupture on a Descent
You are driving a 2019 tractor-trailer combination with a dual air brake system on I-84 near Pendleton, Oregon. Both gauges read about 105 psi.
532 words, about 3 min2Pre-Trip Air Build-Up and Leak Test
You are doing a pre-trip inspection on a 2016 Freightliner tractor with a 53-foot trailer. At fast idle, system pressure rises from 85 to 100 psi in 70 seconds.
358 words, about 2 min3Low-Pressure Warning and Spring Brake Test
You are performing the air brake checks on a 33,000-lb GVWR single-unit truck before a delivery run in Salem. The wheels are chocked, the engine is off, and the parking brake is released.
426 words, about 2 min4Brake Fade on a Six-Percent Grade
You are driving an 80,000-lb tractor-trailer down a 6% grade that runs for 5 miles on Oregon Route 58. You entered the grade at 55 mph in 10th gear and have held the service brake pedal down continuously for about 25 seconds.
447 words, about 2 min5Total Air Loss at Highway Speed
You are driving a loaded three-axle tractor-trailer at 55 mph on I-5 near Eugene. The low-pressure warning buzzer and light activate.
449 words, about 2 min