Combination Vehicles · Practice test 5

Question 1Not answered

How does ABS on a tractor and ABS on a trailer typically communicate their braking status to each other, if at all?

1. Trailer ABS cannot function unless directly wired into the tractor's engine computer
2. The tractor's ABS fully controls the trailer's brakes at all times
3. They generally operate independently, each managing wheel speed for its own axles
4. ABS systems on tractors and trailers are always identical hardware from the same manufacturer

Question 2Not answered

While inspecting a trailer's suspension, you find a cracked leaf spring. What should you do?

1. Do not operate the trailer until the spring is repaired or replaced
2. Reduce the load slightly to compensate for the weaker spring
3. Drive only on smooth highways until it can be looked at
4. Note it for the next scheduled maintenance and continue the trip

Question 3Not answered

How does trailer length affect the amount of off-tracking during a turn?

1. Trailer length has no effect at all on the amount of off-tracking that happens during a turn
2. Shorter trailers always off-track more than longer ones
3. Off-tracking only depends on trailer width, not length
4. A longer trailer generally off-tracks more, cutting a tighter path relative to the tractor

Question 4Not answered

What commonly causes a drive-wheel skid on a combination vehicle?

1. Applying too much throttle on a slippery road, causing the drive wheels to spin
2. Driving well under the speed limit
3. Keeping a long following distance
4. Using a lower gear on a flat, dry road with good tire tread and a light, well-secured load

Question 5Not answered

Why should a driver avoid sudden steering corrections while driving a loaded combination vehicle?

1. A sudden correction can upset the trailer's stability and lead to a skid or rollover
2. It only matters for empty trailers, not loaded ones
3. Sudden corrections are the recommended technique for combination vehicles
4. Sudden corrections have no different effect on a combination vehicle than they do on a car

Question 6Not answered

You are about to uncouple a trailer parked on a slight grade. Why should you chock the trailer's wheels first?

1. It is only necessary in winter weather
2. It prevents the landing gear from being damaged during uncoupling
3. To keep the trailer from rolling once it is no longer held in place by the tractor and its own brakes alone
4. Chocking is only a formality required by some shippers on their own property, not a real safety measure for the driver

Question 7Not answered

After steering to correct an initial skid, why is it important to straighten the wheel again as soon as the vehicle responds?

1. Straightening the wheel immediately always causes a second skid
2. The wheel should be held firmly in the correction until the vehicle comes to a complete and full stop
3. Holding the correction too long can send the vehicle into a skid in the opposite direction
4. It has no effect either way once the first skid is controlled

Question 8Not answered

What is often one of the earliest warning signs that a combination vehicle is about to skid?

1. The radio signal becomes weaker
2. The steering starts to feel unusually light or the trailer feels like it's pushing sideways
3. The engine temperature gauge rises slightly
4. The fuel gauge drops noticeably faster than expected because of the extra aerodynamic drag on the drivetrain

Question 9Not answered

What should a driver do if the trailer's brakes appear to have failed entirely (no braking response) while descending a grade?

1. Rely on the tractor's brakes and engine braking, downshifting further, and use an escape ramp if available
2. Release the tractor's parking brake to compensate
3. Attempt to accelerate to the bottom of the grade as fast as the engine allows to get it over with
4. Shift to neutral to reduce strain on the combination

Question 10Not answered

What should you do if the fifth wheel does not lock properly on your first attempt to couple?

1. Drive away anyway since a partial lock is usually good enough
2. Add extra weight to the trailer's nose to force it down onto the fifth wheel plate by hand
3. Pull forward away from the trailer, reposition, and try backing under again rather than forcing a partial connection
4. Manually force the locking jaws closed with a tool

Question 11Not answered

How should a driver approach a curve differently in a combination vehicle compared to a single unit truck?

1. Accelerate through the curve to keep the trailer stable
2. Approach curves at the same speed as a single unit truck, since trailers do not affect curve handling at all
3. Reduce speed more before the curve, since the trailer can amplify the effects of taking a curve too fast
4. Curve speed adjustments matter only for tankers

Question 12Not answered

What should you check about the trailer landing gear before it is expected to bear the trailer's weight during uncoupling?

1. That it is left partially retracted on purpose for a quicker departure later on in the day
2. Nothing, since landing gear rarely fails
3. Only that it is painted a visible color
4. That it is fully cranked down, not bent, and positioned to support the trailer securely

Question 13Not answered

Why does a combination vehicle need a longer following distance than a single vehicle at the same speed?

1. It's only about visibility in bad weather, not stopping distance under normal conditions
2. It has better brakes so distance matters less
3. It weighs more and takes longer to stop, especially when loaded
4. It only matters in the rain

Question 14Not answered

After backing under a trailer, the fifth wheel's locking indicator does not show that the jaws are fully closed around the kingpin. What should you do?

1. Assume it is a minor indicator issue and proceed if the pull test feels normal
2. Tap the trailer brakes to help the jaws seat properly
3. Back under again and recheck the coupling before doing anything else
4. Add extra safety chains and drive at reduced speed instead of recoupling

Question 15Not answered

Why does a combination vehicle with a longer wheelbase off-track more than one with a shorter wheelbase?

1. Wheelbase length has no relationship to off-tracking
2. A longer wheelbase creates a bigger difference between the front wheels' path and the rear wheels' path in a turn
3. Longer combinations always off-track less than shorter ones because their extra length lets them turn more slowly
4. Off-tracking only depends on tire size, not wheelbase

Question 16Not answered

If a trailer tire fails at highway speed, what should the driver do first?

1. Hold the steering wheel firmly, ease off the accelerator, and move off the road gradually once under control
2. Brake hard immediately regardless of steering stability or how the trailer happens to be tracking
3. Swerve sharply toward the shoulder
4. Accelerate to maintain stability

Question 17Not answered

On a combination vehicle with a sliding fifth wheel, what must you confirm during inspection besides the coupling itself?

1. That the fifth wheel is centered on the frame, regardless of whether the locking pins are engaged
2. That the fifth wheel slides freely at all times, even while driving
3. That the sliding mechanism is freshly painted
4. That the sliding fifth wheel's locking pins are fully engaged so it cannot shift under load

Question 18Not answered

What is a general benefit of ABS during an emergency stop on a wet or slippery surface?

1. It has no effect on wet or slippery surfaces, only on dry pavement
2. It helps the driver maintain steering control by preventing the wheels from locking and skidding straight ahead
3. It guarantees the vehicle will stop within a fixed, shorter distance no matter what the road conditions are
4. It disables the trailer brakes automatically for safety

Question 19Not answered

Why does a combination vehicle need more space to change lanes safely than a single straight truck?

1. Combination vehicles change lanes just as quickly as any other passenger vehicle on the road
2. Its overall length means it takes longer to fully clear the lane it is leaving
3. Lane change distance is unrelated to overall vehicle length
4. It matters only when towing two trailers, not one

Question 20Not answered

When uncoupling a trailer, why should you disconnect the air lines and electrical cable only after the landing gear is down and the trailer's brakes are set?

1. Disconnecting them first removes the trailer's brake supply and could let it roll while still connected
2. Lines and cables must always be disconnected first so the landing gear crank handle isn't physically blocked
3. It is only a convention to keep the lines clean, not a safety step
4. The order makes no real difference as long as everything is disconnected eventually

Question 21Not answered

Before backing under a trailer, why should you check that the trailer height is properly set relative to the tractor's fifth wheel?

1. Height only matters for oversized loads
2. A trailer set too high or too low can prevent proper coupling or damage the fifth wheel
3. Trailer height has no effect on how coupling occurs
4. It is checked only after coupling is already fully complete, never beforehand while backing under

Question 22Not answered

Why should a driver position the tractor slightly to the left before making a tight right turn in a combination vehicle?

1. It gives the trailer's wheels room to off-track without hitting the curb or an object on the right
2. It is done only to improve the driver's view of oncoming traffic
3. It is required only for turns wider than 90 degrees
4. Positioning left has no relationship at all to how the trailer actually tracks through the turn

Question 23Not answered

What early warning sign might a driver notice in the mirrors just before a trailer begins to skid or sway?

1. The trailer always appears perfectly steady right up until a full skid begins with no warning
2. A change in trailer color visible in the mirror
3. The trailer appearing to drift slightly out of its expected lane position
4. The trailer's turn signal flashing faster than normal

Question 24Not answered

How can a driver use mirrors to help manage off-tracking during a turn?

1. Mirrors are useful only after the turn is fully completed
2. Mirrors provide no useful information at all about off-tracking while the turn is being completed
3. Only the passenger side mirror is relevant to off-tracking
4. By watching the trailer's wheels and body in the mirrors to confirm it clears curbs and objects as the turn is completed

Question 25Not answered

How is the presence of ABS on a trailer typically identified from outside the vehicle?

1. ABS trailers have a special license plate
2. A yellow ABS indicator lamp is mounted on the left side of the trailer, visible during a pre-trip check
3. There is no way to identify ABS presence on a trailer without disassembling its brake components
4. ABS-equipped trailers are always a different color than non-ABS trailers

Question 26Not answered

What should a driver do if, partway through a turn, they realize the trailer is about to hit a curb or object due to off-tracking?

1. Continue exactly as planned since the trailer's path can never be adjusted once the turn has begun
2. Slow down or stop if possible, and adjust the tractor's path if there is still room to do so safely
3. Reverse suddenly to avoid the object
4. Speed up to complete the turn before contact happens

Question 27Not answered

What should you verify about the trailer's electrical connection (the 'pigtail' or connector) during your inspection?

1. That it is disconnected before every trip for safety
2. Only that the connector color matches the tractor's
3. Nothing, since trailer lights are tested only once a year at the annual inspection
4. That it is securely connected and the trailer's lights function correctly when tested

Question 28Not answered

Why should a driver avoid downshifting too aggressively while already in a curve with a loaded trailer?

1. It is the recommended way to slow down safely mid-curve
2. It can upset the vehicle's balance mid-curve, similar to hard braking or sharp steering
3. Downshifting in a curve has no effect on vehicle stability compared to shifting on straight road
4. It only matters for vehicles with automatic transmissions

Question 29Not answered

The engine hood latch fails and the hood flies up, blocking your forward view while driving. What should you do?

1. Brake hard and stop immediately in the travel lane
2. Slow down gradually while looking through any gap or side window, and pull off the road as soon as it's safe
3. Reach out the driver's window to try to hold the hood down by hand while still driving at speed
4. Speed up to force air pressure to hold the hood back down

Question 30Not answered

Before backing under a trailer, why should you check that the trailer's height is slightly lower than the fifth wheel?

1. So the fifth wheel raises the trailer slightly as it slides underneath, locking on properly
2. It only matters for appearance once the units are coupled
3. A trailer that sits too low is always too heavy to couple safely and needs to be reloaded first
4. Trailer height has no bearing on how the coupling engages