CDL Combination Vehicles case studies
CDL Combination Vehicles · Put your knowledge to work in context.
The CDL Combination Vehicles knowledge test is the written exam a driver must pass to operate a tractor-trailer or other combination vehicle. It is required for a Class A commercial driver's license and is also taken by drivers adding combination-vehicle authority to an existing CDL. It is a multiple-choice knowledge test, not a skills test; the behind-the-wheel inspection and driving portions are separate. The questions test whether you understand how a tractor and trailer behave as one unit: how air brakes and the trailer protection valve interact, how to couple and uncouple without dropping a trailer, what a complete pre-trip inspection must cover, why the rear wheels of a long trailer cut the corner, how to steer out of a trailer skid, and how to prevent jackknifing and rollover. The CDL Combination Vehicles case studies are 5 cases and about 2,943 words.
1Leak-Down Test Fails on a Loaded Tractor-Trailer
A driver is pre-tripping a 3-axle tractor and a loaded 53-foot van at 0600. The outside temperature is 28°F.
530 words, about 3 min2Fifth Wheel Looks Latched, But There Is a Gap
A driver is coupling to a loaded 53-foot dry van at a shipper. The trailer is at 49 inches; the tractor's sliding fifth wheel is set at 47 inches.
651 words, about 3 min3Right Turn With a 53-Foot Trailer and a Car on the Left
A driver is turning right from a three-lane one-way street onto a two-lane street. His combination is a 3-axle tractor and a 53-foot trailer.
622 words, about 3 min4Empty Trailer, Icy Bridge, and a Trailer Hand Valve
A driver is pulling an empty 53-foot van across a concrete bridge at 45 mph. The temperature is 30°F, and the bridge deck has patchy ice; the approach is wet but not icy.
572 words, about 3 min5Two Straps for an 8,000-Pound Steel Plate
A driver is securing an 8,000-pound steel plate on a flatbed. The plate is 20 feet long and sits directly on the deck; there is no headboard.
568 words, about 3 min