CDL combination vehicles practice test 2

A: Keep the cargo as close to the ground as possible, and drive slowly around turns. The manual names two keys to avoiding rollover: load the cargo as low as you can, and take turns slowly. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.1 Rollover Risks, page 6-1.

A: You can roll the last trailer 3.5 times as easily as a five-axle tractor. A rearward amplification of 3.5 means the last trailer of a triples rig rolls over 3.5 times as easily as a five-axle tractor. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.2 Steer Gently, page 6-1.

D: When the trailer is empty or lightly loaded. A trailer swinging around after its wheels lock is more likely when the trailer is empty or lightly loaded. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.5 Prevent Trailer Skids, page 6-2.

C: Steer the front end wide enough that the rear end doesn't run over the curb, pedestrians, and so on. Swing the front end out far enough that the rear wheels clear the curb and pedestrians, while keeping the back of the rig near the curb. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.6 Turn Wide, page 6-3.

B: So you can back in a straight line. Whenever you back with a trailer, try to position the vehicle so you can back in a straight line. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.7 Backing with a Trailer, page 6-3.

A: If the load is to one side and makes the trailer lean, a rollover is more likely. If the load is to one side so the trailer leans, a rollover is more likely, so keep cargo centered and spread out as much as possible. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.1 Rollover Risks, page 6-1.

B: The trailer could tip over. Steer gently and smoothly when pulling trailers; a sudden steering movement could tip the trailer over. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.2 Steer Gently, page 6-1.

C: Seeing it in your mirrors. The earliest and best way to recognize a trailer skid is by seeing it in your mirrors. Check the mirrors any time you brake hard. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.5 Prevent Trailer Skids, page 6-2.

B: To stop other drivers from passing you on the right. Keeping the rear close to the curb stops other drivers from passing you on the right. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.6 Turn Wide, page 6-3.

D: Toward the driver's side, so you can see. When a curved path can't be avoided, back toward the driver's side, where you can see the trailer. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.7 Backing with a Trailer, page 6-3.

B: When you turn too fast. Rollovers happen when you turn too fast. Drive slowly around corners and on on-ramps and off-ramps, and avoid quick lane changes, especially when fully loaded. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.1 Rollover Risks, page 6-1.

A: To make sure the trailer is staying where it should be. Any time you brake hard, check the mirrors to make sure the trailer stays where it should. Once it swings out of your lane, a jackknife is very hard to prevent. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.5 Prevent Trailer Skids, page 6-2.

B: Turn wide as you complete the turn. Make the wide swing at the end of the turn instead of swinging left first. That way, other drivers can't slip past you on the right. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.6 Turn Wide, page 6-3.

B: Get out and walk around the vehicle to check your path and clearances. Before backing, check your path: get out, walk around the rig, and look at side and overhead clearance along the route. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.7 Backing with a Trailer, page 6-4.

C: More important. A low load matters even more in a combination vehicle than in a straight truck. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.1 Rollover Risks, page 6-1.

A: Stop using the brake to let the trailer wheels regain traction. Let off the brakes so the trailer tires regain traction. Once they grip again, the trailer will fall back in line behind the tractor. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.5 Prevent Trailer Skids, page 6-3.

B: Between the rear of the tractor frame and the landing gear, and between the tractor tires and the trailer nose. Check clearance between the rear of the tractor frame and the landing gear, which it must not hit in sharp turns, and between the tops of the tractor tires and the trailer nose. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.1 Coupling Tractor-Semitrailers, page 6-9.

A: So you can make corrections before you get too far off course. Backing slowly lets you make corrections before you get too far off course. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.7 Backing with a Trailer, page 6-4.

C: Slowly enough to see obstacles with your headlights in time to change lanes or stop gently. After dark, keep your speed low enough that your headlights show an obstacle while you still have time to change lanes or stop smoothly. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.2 Steer Gently, page 6-1.

C: The brakes on the trailer wheels caused the skid in the first place. Using the trailer hand brake to straighten out the rig is the wrong thing to do, since the trailer wheel brakes caused the skid in the first place. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.5 Prevent Trailer Skids, page 6-3.

D: The tractor frame could hit the landing gear, or the cab could hit the trailer, during turns. Check that the fifth wheel isn't so far forward that the tractor frame will hit the landing gear, or the cab hit the trailer, during turns. Commercial Driver's License Manual (CDL Driver's Manual): 6.5.1 Additional Things to Check during a Walk-around Inspection, page 6-13.

C: Turn the top of the steering wheel in the direction of the drift. As soon as the trailer starts to drift, correct it by turning the top of the wheel toward the drift. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.7 Backing with a Trailer, page 6-4.

A: Low-slung units such as a lowboy, car carrier, moving van, or possum-belly livestock trailer. Trailers with low underneath clearance, such as lowboys, car carriers, moving vans, and possum-belly livestock trailers, can get stuck on raised crossings. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.4 Railroad-highway Crossings, page 6-2.

A: To keep air in the tractor or truck brake system if the trailer breaks away or develops a bad leak. If the trailer breaks away or develops a bad leak, the tractor protection valve keeps the tractor's (or truck's) own brake air from escaping. Commercial Driver's License Manual (CDL Driver's Manual): 6.2.2 Tractor Protection Valve, page 6-5.

A: Make pull-ups to reposition the vehicle as needed. Make pull-ups (pull forward) to reposition your vehicle as needed. Commercial Driver's License Manual (CDL Driver's Manual): 6.1.7 Backing with a Trailer, page 6-4.