OR CDL Combination case studies
OR CDL Combination · Put your knowledge to work in context.
The Oregon CDL Combination Vehicles knowledge test is the written exam a driver must pass to add the Class A combination-vehicle endorsement path to an Oregon commercial learner permit or commercial driver license. It is aimed at people who plan to drive tractor-trailers, doubles, or other vehicles with a towed unit, and who therefore need to show they understand coupling, inspection, air brakes, and safe handling before taking a CDL skills test. The OR CDL Combination case studies are 5 cases and about 2,432 words.
1Fifth Wheel Gap After Coupling
At a Portland yard, you are assigned a 53-foot dry van loaded with 38,000 lb of packaged goods. The tractor is a 2021 Freightliner with a sliding fifth wheel, currently set at 42 inches.
578 words, about 3 min2Brake Fade on a Six Percent Grade
On I-84 westbound near Cabbage Hill, you are driving a 78,000-lb combination: a three-axle tractor and a 53-foot van loaded to 44,000 lb. The grade is 6% for the next 4 miles.
500 words, about 3 min3Combination Air Leak Test Failure
After coupling to a loaded trailer at a Bend truck stop, you run the air brake check. With the engine off and the parking brake released, pressure falls from 125 to 119 psi in 60 seconds.
465 words, about 2 min4Trailer Jackknife on a Wet Curve
On a wet two-lane highway near Hood River, you are driving a 75,000-lb combination with a 45-foot flatbed loaded with lumber. The trailer has a high center of gravity.
420 words, about 2 min5Overweight Trailer Tandem and Insufficient Securement
At a weigh station on I-5 near Medford, your 53-foot van scales: steer axle 11,900 lb, drive tandem 33,800 lb, trailer tandem 35,600 lb, gross 81,300 lb. The trailer tandems are set 10 feet from the rear.
469 words, about 2 min