Combination Vehicles · Practice test 4

Question 1Not answered

You need to accelerate from a stop on a wet or icy road while pulling a loaded trailer. What should you keep in mind?

1. Accelerate gradually, since sudden power can spin the drive wheels and start a skid
2. Traction is only a concern when braking, not when accelerating
3. Loaded trailers add enough weight that wheel spin isn't a concern
4. Accelerate hard and briefly to get through the slick section quickly before losing momentum

Question 2Not answered

Why is it important to be aware of the trailer's tail swing when making a turn in a combination vehicle?

1. It matters only for trailers over 53 feet long
2. The rear of the trailer can swing wide of the tractor's path, potentially hitting something the driver did not account for
3. Trailers always follow the exact same path as the tractor with absolutely no swing at the rear end
4. Tail swing only matters when backing, never during forward turns

Question 3Not answered

Before uncoupling a trailer, why must you lower the landing gear until it just touches the ground before disconnecting the fifth wheel?

1. To make the trailer easier to see at night, which has nothing to do with how the fifth wheel releases
2. So the trailer stays supported once the fifth wheel releases, instead of dropping suddenly
3. To reduce wear on the trailer's tires
4. It is only a cosmetic step with no safety purpose

Question 4Not answered

The trailer's ABS malfunction lamp stays on after starting the vehicle. What does this tell you?

1. The trailer's ABS is not functioning, though the regular brakes still work
2. The trailer has no brakes at all
3. The tractor's engine has a mechanical problem unrelated to the trailer's own brake system
4. The trailer is overloaded

Question 5Not answered

Your combination vehicle experiences a total loss of service brakes while driving. What should you do?

1. Turn off the engine immediately while still at highway speed
2. Use the parking (emergency) brake system and downshift, steering toward an escape route or safe area to stop
3. Shift into the highest gear available to slow down faster
4. Continue driving normally, since air brake systems on a combination vehicle cannot fail completely under any circumstance

Question 6Not answered

How can a driver use the side mirrors to judge off-tracking while completing a turn?

1. Mirrors cannot show anything useful about off-tracking at all, only forward visibility actually helps a driver
2. By watching the trailer's rear wheels in the mirror to see how closely they track the curb or lane markings during the turn
3. By checking the mirror only after the turn is finished
4. By watching the front bumper's distance from the curb instead of the trailer

Question 7Not answered

How can you tell whether an older trailer in your combination is equipped with ABS?

1. All trailers built at any time automatically have ABS
2. Check for an ABS indicator lamp, often near the left rear of the trailer
3. There is no way to tell without disassembling the brakes and inspecting the wheel hub
4. ABS can only be identified by the trailer's paint color

Question 8Not answered

When coupling a trailer, in what order should you generally connect the air lines?

1. Connect only the service line, since the emergency line is optional equipment on most modern trailers built today
2. Connect the electrical cable before either air line, every time
3. Order does not matter as long as both lines end up connected
4. Connect the emergency (supply) line, then the service line, keeping lines from crossing or twisting

Question 9Not answered

Why should you check the trailer's frame and cross members for cracks or corrosion during an inspection?

1. Surface corrosion is purely a cosmetic issue on any trailer type
2. Frame condition only affects the trailer's resale value down the road, not its day-to-day safety
3. Frame cracks are cosmetic and do not affect performance
4. Structural damage can weaken the trailer's ability to support cargo and stay stable during driving

Question 10Not answered

During a pre-trip inspection of the fifth wheel, why should you check the upper coupler plate and kingpin for wear?

1. Wear on those parts only affects how smoothly the trailer swivels on tight turns, not the coupling's overall safety
2. Kingpin wear is cosmetic and gets fixed at the next scheduled service
3. It is checked only for warranty purposes, not for a pre-trip safety reason
4. Excessive wear there can let the trailer shift or separate under the stress of driving, even if the jaws appear locked

Question 11Not answered

Why should you check that the tractor frame clears the trailer's landing gear as you pull away after uncoupling?

1. Landing gear clearance is never a real concern once the trailer has already been uncoupled from the tractor
2. It only matters for trailers with automatic landing gear
3. It is checked only during the initial coupling, not when leaving
4. Pulling out too sharply or too soon can cause the tractor to strike the landing gear or trailer nose

Question 12Not answered

How does off-tracking interact with a marked turn lane that has a tight curb radius, such as at some urban intersections?

1. Off-tracking is a concern only on roads without marked turn lanes
2. A tight curb radius leaves less margin for the trailer's off-tracking path, increasing the risk of hitting the curb
3. Tight curb radii have no effect on off-tracking outcomes
4. Marked turn lanes are always wide enough to accommodate any trailer length or wheelbase configuration

Question 13Not answered

Why should you avoid making quick, last-second lane changes when driving a combination vehicle?

1. Lane changes only affect fuel economy, not safety, for a combination vehicle
2. Quick lane changes save the most time and are preferred once traffic allows it
3. The trailer automatically corrects its position regardless of how quickly or slowly the lane change is made
4. The trailer needs the full width of the new lane and more time to complete the move safely behind the tractor

Question 14Not answered

You are driving a combination vehicle around a sharp turn. What should you keep in mind about the trailer's path?

1. The trailer always follows the exact same path as the tractor
2. The trailer swings wider than the tractor on the outside of the turn, so hug the inside as tightly as you can manage
3. Trailer path doesn't matter as long as you signal early
4. The trailer's wheels track a shorter path than the tractor's, so swing wide enough to keep the trailer's rear wheels clear

Question 15Not answered

While backing under a trailer to couple, you feel the tractor's frame bump hard into the trailer's nose before the fifth wheel engages. What does this suggest?

1. The trailer was set too low for the fifth wheel and the coupling can still be trusted anyway without a recheck
2. This is a normal part of every coupling and needs no further check
3. The trailer height was set correctly and coupling proceeded normally
4. The trailer was set too high, so the tractor struck it instead of sliding underneath, and the coupling should be rechecked

Question 16Not answered

How does an overloaded trailer, or one with an unusually high center of gravity, affect skid and rollover risk in a curve?

1. It increases the risk, since more weight positioned higher makes the vehicle less stable during a hard turn
2. A higher center of gravity always reduces rollover risk
3. Load height and weight distribution have no effect at all on rollover risk during a hard turn
4. It only matters for flatbed trailers, not enclosed ones

Question 17Not answered

Why can excessive use of the trailer hand valve (the separate trailer brake control) increase skid risk?

1. Applying only the trailer brakes hard can cause the trailer wheels to lock and the trailer to swing out
2. Using the trailer hand valve always improves stability
3. It is designed to be used as the primary everyday brake at all times instead of the foot pedal
4. The trailer hand valve has no bearing on skid risk

Question 18Not answered

Why is it dangerous to depend only on the trailer hand valve to slow a combination vehicle in an emergency?

1. Using it alone can cause the trailer to skid or jackknife because it doesn't apply the tractor's brakes
2. It has no effect on braking at all
3. It only works below 10 mph
4. It applies more force than the foot pedal and stops the vehicle too quickly for the traffic following close behind

Question 19Not answered

What risk does off-tracking create for other road users, such as pedestrians or cyclists, at an intersection?

1. Someone standing near the inside of the turn radius could be struck by the trailer even if the tractor cleared them safely
2. Off-tracking risk applies only at highway speeds, not intersections
3. Off-tracking only affects vehicles, never pedestrians or cyclists
4. Pedestrians are never at any real risk from a trailer's path once the tractor cab has already passed them

Question 20Not answered

Why should a driver avoid slamming on the brakes if the trailer suddenly starts to separate slightly from the tractor at a stoplight or low speed?

1. Coupling issues at low speed present no real risk
2. It has no bearing on the coupling's condition either way
3. Hard braking always fully re-secures a loose coupling no matter how far it has separated
4. A sudden hard brake could worsen an already compromised connection between the units

Question 21Not answered

Why should you check your mirrors regularly while driving a combination vehicle, beyond watching for traffic?

1. To confirm the trailer is tracking straight and not swaying or drifting
2. It's only useful for seeing the license plate is still attached
3. Mirrors on a combination vehicle are mainly for checking your own appearance
4. Checking mirrors is only necessary right before a lane change

Question 22Not answered

When inspecting the coupling area of a combination vehicle, what should you check the fifth wheel for?

1. That it is securely mounted, properly lubricated, and the locking jaws are closed around the kingpin
2. That it makes a clicking sound while the vehicle moves, which by itself does not confirm the jaws are actually closed
3. That it is the same brand as the tractor
4. That it matches the trailer's paint color

Question 23Not answered

Why should you always chock the trailer wheels or apply the trailer brakes before starting the coupling process?

1. Chocking is only necessary when uncoupling, never before you start coupling a trailer
2. It is required only for trailers heavier than 40,000 pounds
3. It has no effect on how safely coupling can be performed
4. It prevents the trailer from rolling while the tractor is backing up to it

Question 24Not answered

What is a common misunderstanding about what ABS does for a combination vehicle?

1. Assuming ABS replaces the need for any other braking system at all, including the parking and emergency brakes
2. Assuming ABS always shortens stopping distance, when its main benefit is helping the driver keep steering control
3. Assuming ABS has no effect on the vehicle at all
4. Assuming ABS only works on the trailer, never the tractor

Question 25Not answered

What is a common misconception about what antilock brakes do on a combination vehicle?

1. That ABS shortens stopping distance, when its main job is helping the driver keep steering control during hard braking
2. That ABS only works on the tractor's wheels and never activates anywhere on the trailer's own axles
3. That ABS needs to be manually turned on before each trip
4. That ABS replaces the need for a functioning parking brake

Question 26Not answered

You are approaching a downgrade with a fully loaded combination vehicle. What should you do before starting down?

1. Wait until you feel the vehicle speeding up, then react
2. Shift to neutral so the engine doesn't work against gravity while descending the grade
3. Keep the same gear and speed you were using on flat ground
4. Reduce your speed and select a low gear before the grade gets steep

Question 27Not answered

What commonly causes a trailer to jackknife?

1. Using the engine brake on a flat road
2. Driving too slowly on the highway
3. Braking too hard, causing the trailer wheels to lock up and swing out
4. Having too little cargo weight in the trailer, which reduces traction on the drive axles

Question 28Not answered

What is a 'trailer swing' skid, and how does it differ from a tractor jackknife?

1. It refers to a skid caused only by steering axle failure
2. It is simply another term for the exact same event as a tractor jackknife, just used a bit differently
3. It only happens when the trailer is empty
4. It is when the trailer itself skids sideways, sometimes due to trailer brakes locking, rather than the tractor's drive wheels

Question 29Not answered

Why is it important to check the trailer's tandem axle slider (if equipped) for proper locking before a trip?

1. Slider locking has no effect on trailer stability once moving
2. Sliders are purely cosmetic adjustments on the underside of the trailer with no real safety function
3. It only matters when the trailer is being loaded, not during driving
4. An unlocked slider can shift under braking or acceleration, changing weight distribution unexpectedly

Question 30Not answered

While driving a loaded combination vehicle, you feel the trailer shift slightly and hear a thump from the cargo area. What should you do?

1. Assume it is normal road noise and take no action
2. Pull over at the next safe location and check the load and its securement before continuing
3. Increase speed to reduce the amount of time the shifted load has to keep moving around further
4. Continue on and check the cargo only once you reach your destination