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Question 1 of 65
Why are combination vehicles harder to drive than single units?
Correct answer: A. They have more pivot points, are longer, and have rearward amplification
Why: Multiple articulation points and length increase complexity.
Question 2 of 65
Rearward amplification (the "crack-the-whip" effect) is greater in:
Correct answer: A. Doubles and triples
Why: Each additional trailer multiplies sway intensity at the rear.
Question 3 of 65
When a trailer skid occurs, the recommended action is:
Correct answer: A. Release the brakes to allow trailer wheels to roll, countersteer if needed
Why: Releasing brakes restores traction; countersteer to keep tractor straight.
Question 4 of 65
What is "trailer jackknife"?
Correct answer: A. Trailer swings out of line with the tractor, often forming a near-90° angle
Why: Caused by locked or skidding trailer wheels; difficult to recover.
Question 5 of 65
When coupling, the fifth wheel jaws should:
Correct answer: A. Lock around the kingpin completely with the safety latch closed
Why: Verify with pull test and visual check under trailer.
Question 6 of 65
Before coupling, you should check that:
Correct answer: A. Fifth wheel is properly greased and tilted slightly down at rear
Why: Greased fifth wheel and slight downward rake make coupling safer.
Question 7 of 65
When backing under a trailer, you should:
Correct answer: A. Back slowly until the kingpin is captured
Why: Slow approach, contact, then push slightly to lock jaws.
Question 8 of 65
How do you test that the fifth wheel is locked?
Correct answer: A. With trailer brakes set, pull forward gently in low gear
Why: Pull test: tractor must not separate.
Question 9 of 65
When uncoupling, lower the landing gear so:
Correct answer: A. It just touches the ground, then crank a few more turns
Why: Landing gear should support trailer with weight slightly transferred from fifth wheel.
Question 10 of 65
What is "off-tracking" in combination vehicles?
Correct answer: A. Rear trailer wheels follow a path inside the front wheels in turns
Why: Long combinations off-track significantly; you must swing wide.
Question 11 of 65
When passing a curve, longer combinations may need to:
Correct answer: A. Use part of the next lane to keep trailer on the road
Why: Off-tracking forces the rear toward the inside of the curve.
Question 12 of 65
Antilock braking systems on combinations help by:
Correct answer: A. Preventing wheel lockup so steering and stability are retained
Why: ABS keeps wheels rolling; combinations gain stability.
Question 13 of 65
How do you adjust your driving when towing an empty trailer?
Correct answer: A. Increase following distance — empty trailers are easier to skid
Why: Less weight on tires reduces traction; brakes designed for full load can lock the wheels.
Question 14 of 65
What does the term "bobtail tractor" mean?
Correct answer: A. Tractor without a trailer
Why: Bobtail = tractor only.
Question 15 of 65
Which of these is true about coupling air lines?
Correct answer: A. Service line glad hand to service, emergency to emergency, locked properly
Why: Color coded blue = service, red = emergency; misconnections must be avoided.
Question 16 of 65
Why should you check trailer tires more carefully on combinations?
Correct answer: A. Trailer tires are often older, worn, and more numerous
Why: Trailer tires often log many miles between visual checks.
Question 17 of 65
How can you tell that the height of the trailer is right for coupling?
Correct answer: A. It is just low enough that the tractor will lift it slightly when backed under
Why: Slight lift confirms the trailer kingpin will engage the jaws.
Question 18 of 65
What can you do to help prevent trailer jackknife?
Correct answer: A. Slow before turns, avoid hard braking on slippery surfaces
Why: Smooth control inputs and proper speed prevent skid.
Question 19 of 65
When pulling triples, the third (rear) trailer:
Correct answer: A. Has the most rearward amplification — most likely to roll over
Why: Sway amplifies through each trailer; the rear is most vulnerable.
Question 20 of 65
Which of these is the most dangerous on a combination vehicle?
Correct answer: A. Quick lane changes — they amplify trailer sway
Why: Sudden steering causes rearward amplification.
Question 21 of 65
When emergency situations require braking, on a combination vehicle without ABS use:
Correct answer: A. Controlled or stab braking
Why: Controlled or stab braking prevents wheel lockup.
Question 22 of 65
What is the maximum gross combination weight rating (GCWR) for a Class A CDL?
Correct answer: A. 26,001 lbs or more with towed unit over 10,000 lbs
Why: Class A defined by GCWR ≥ 26,001 lbs and a towed unit > 10,000 lbs.
Question 23 of 65
When backing a trailer, turn the steering wheel:
Correct answer: A. In the direction opposite of where you want the trailer rear to go
Why: Steering wheel turns opposite to desired trailer rear direction.
Question 24 of 65
When backing in a straight line, correct drift by:
Correct answer: A. Small steering inputs and/or pulling forward to reset
Why: Small inputs and resetting prevents jackknife.
Question 25 of 65
Why is securement in combinations critical?
Correct answer: A. Cargo shifting can affect handling, brake balance, and rollover risk
Why: Shifted cargo changes weight distribution and handling.
Question 26 of 65
What is the purpose of safety chains on a converter dolly?
Correct answer: A. Hold the dolly to the trailer if the pintle hook fails
Why: Safety chains catch the dolly if the pintle releases.
Question 27 of 65
When pulling a refrigerated trailer, the reefer fuel is checked:
Correct answer: A. Before each trip and during long trips
Why: Refrigerated trailer fuel must be sufficient for the trip.
Question 28 of 65
What is "dock walk"?
Correct answer: A. Trailer wheels creep away from the dock as workers load — apply parking brakes and chock
Why: Vibration from forklifts can move trailer; chock wheels.
Question 29 of 65
When you are driving a combination on a wet road, you should:
Correct answer: A. Reduce speed by about a third
Why: Reduce speed by ~1/3 on wet, ~1/2 on snow.
Question 30 of 65
Why should you never use the trailer hand valve in driving?
Correct answer: A. Using only trailer brakes can cause skid/jackknife
Why: Trailer-only braking risks trailer skid and jackknife.
Question 31 of 65
Which one of these brake systems applies and releases the brakes when the driver uses the brake pedal?
Correct answer: A. Service brake
Why: Service brake = foot pedal.
Question 32 of 65
Which of the following is the proper procedure for connecting the air lines?
Correct answer: A. Check seals, lock glad hands, supply red, service blue
Why: Verify seals, lock the glad hands, color-coded.
Question 33 of 65
Which is true about coupling triples?
Correct answer: A. Couple front trailer to tractor first, then add subsequent trailers using converter dollies
Why: Always couple front to back to maintain control.
Question 34 of 65
What is a "converter dolly"?
Correct answer: A. Single axle with a fifth wheel that converts a semitrailer into a full trailer
Why: Converter dolly allows pulling additional semitrailers.
Question 35 of 65
Pintle hooks should be checked for:
Correct answer: A. Proper engagement, locks, and secondary safety devices
Why: Pintle hook integrity is critical to safe coupling.
Question 36 of 65
Why should you avoid backing a combination if possible?
Correct answer: A. Backing combinations is one of the most dangerous maneuvers
Why: Many crashes occur during combination backing; plan to pull through.
Question 37 of 65
Why use a helper when backing?
Correct answer: A. To watch blind spots and signal you
Why: Helpers cover what mirrors miss; agree on stop signal first.
Question 38 of 65
How do you avoid trailer skids?
Correct answer: A. Drive smoothly, avoid hard braking, slow before curves
Why: Smooth, anticipatory inputs prevent skids.
Question 39 of 65
When the trailer ABS warning light is on, you should:
Correct answer: A. Treat trailer brakes as conventional, plan for repair
Why: Standard brakes still operate.
Question 40 of 65
What is the trailer hand valve typically used for?
Correct answer: A. Testing trailer brakes — never as parking brake or to stop alone
Why: Use is testing only — does not replace service brake.
Question 41 of 65
Which of the following is true about coupling/uncoupling on a slope?
Correct answer: A. Avoid if possible — chock wheels and use parking brakes
Why: Slopes increase rollaway risk; chocking is essential.
Question 42 of 65
What does it mean if the kingpin pops up after coupling?
Correct answer: A. Trailer is not properly engaged — recouple
Why: A raised pin or visible gap means coupling failed.
Question 43 of 65
What air pressure should you have before driving a combination?
Correct answer: A. At least 100 psi
Why: Build to operating range (100–125 psi) before moving.
Question 44 of 65
How can you test the trailer service brakes?
Correct answer: A. Pull at 5 mph and apply trailer hand valve gently
Why: Hand valve at slow speed checks trailer service brake response.
Question 45 of 65
What can cause a trailer to swing wide on a turn?
Correct answer: A. Off-tracking — rear wheels follow inside path
Why: Off-tracking means the rear cuts inside the front path on turns.
Question 46 of 65
What should you do if the trailer starts swaying?
Correct answer: A. Slow down by easing off accelerator without brakes
Why: Easing off lets sway dampen naturally.
Question 47 of 65
What can cause coupling problems with the fifth wheel?
Correct answer: A. Loose mounting bolts, broken or worn parts, improper greasing
Why: Inspect for cracks, missing bolts, lubrication.
Question 48 of 65
Why must trailer landing gear be fully retracted before driving?
Correct answer: A. It can drag, hit obstacles, or cause damage
Why: Fully retracted gear avoids ground strikes.
Question 49 of 65
When uncoupling, after lowering the landing gear, the next step is:
Correct answer: A. Disconnect air lines and electrical, secure them, then release fifth wheel
Why: Lines first, then release fifth wheel, then drive forward slowly.
Question 50 of 65
Why drive the tractor only halfway out from under the trailer first?
Correct answer: A. Confirms landing gear can hold the trailer
Why: Tractor halfway out is a safety check before full release.
Question 51 of 65
What does "tracking" mean for combinations?
Correct answer: A. How well the trailer follows the tractor through a turn
Why: Tracking concerns lateral path of trailer wheels.
Question 52 of 65
When pulling out of the driving lane to make a wide right turn, you risk:
Correct answer: A. Other drivers passing on the right and being squeezed
Why: Always keep trailer rear close to curb; if you swing left first, drivers may slip in on the right.
Question 53 of 65
What is the danger of a trailer rolling over?
Correct answer: A. Higher center of gravity than truck — can roll easily, especially with liquid loads
Why: Trailer rollovers are common; high CG and turn dynamics.
Question 54 of 65
Inspecting the upper coupler involves checking:
Correct answer: A. Kingpin and fifth-wheel plate for cracks and proper mounting
Why: Upper coupler = trailer side; check kingpin and apron.
Question 55 of 65
How often should fifth wheels be greased?
Correct answer: A. Per manufacturer schedule, typically each lubrication cycle
Why: Greasing the fifth wheel is part of normal preventive maintenance.
Question 56 of 65
What is the function of a slider on a fifth wheel?
Correct answer: A. Allows weight redistribution by sliding the fifth wheel forward or back
Why: Sliding fifth wheel adjusts axle weights for legal load distribution.
Question 57 of 65
What is the function of the safety chains?
Correct answer: A. Backup retention if pintle hook fails on a dolly
Why: Required on dollies and certain trailers as backup.
Question 58 of 65
Why position your tractor in front of the trailer before backing under?
Correct answer: A. Square alignment makes coupling and prevents missed kingpin
Why: Square alignment is essential to safe coupling.
Question 59 of 65
Why do you put on the parking brake of the tractor when uncoupling?
Correct answer: A. Prevents tractor rollaway during uncoupling
Why: Set both tractor and trailer brakes during uncoupling.
Question 60 of 65
When backing into a parking spot, the safest approach is:
Correct answer: A. Driver-side back so you can see the rear of the trailer
Why: Driver-side (sight-side) backing maximizes visibility.
Question 61 of 65
What is a "pup" trailer?
Correct answer: A. A short trailer used in doubles, often 26-29 ft
Why: Pup trailers are common in LCV doubles configurations.
Question 62 of 65
When pulling doubles, place the heaviest trailer:
Correct answer: A. Behind the tractor (lead position)
Why: Heaviest goes immediately behind tractor for stability.
Question 63 of 65
When inspecting a converter dolly, check the:
Correct answer: A. Pintle hook, safety chains, fifth wheel, air and electrical lines
Why: Dolly inspection includes coupling components.
Question 64 of 65
How can you tell that the second trailer is properly coupled to the dolly?
Correct answer: A. Pull test, visual check, inspect kingpin engagement
Why: Same standards as primary fifth wheel.
Question 65 of 65
What is the safest way to disconnect a converter dolly?
Correct answer: A. Lower trailer landing gear, disconnect dolly air/electric, unlock fifth wheel, pull dolly out
Why: Standard procedure prevents trailer drop and damage.