Combination Vehicles · Practice test 1

Question 1Not 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 2Not 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 3Not 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 4Not 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 5Not 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 6Not 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 7Not 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 8Not 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 9Not 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 10Not 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

Question 11Not answered

The accelerator pedal sticks and the engine keeps accelerating even though your foot is off it. What should you do?

1. Turn off the engine immediately while still at highway speed
2. Shift to neutral or push the clutch in, and brake to slow down while steering to a safe stop
3. Continue driving normally since the cruise control will disengage the throttle on its own
4. Pump the accelerator repeatedly to try to free it

Question 12Not answered

You are approaching a work zone with narrowed lanes while pulling a trailer. What should you do?

1. Match your speed to the smallest vehicles nearby regardless of your own stopping distance
2. Move into the narrow lane as late as possible to keep traffic flowing
3. Slow down earlier than other traffic and increase following distance before the lane narrows
4. Maintain highway speed since work zones are designed for all vehicle sizes equally

Question 13Not answered

If you notice the trailer's landing gear was not fully retracted before driving away, what should you do as soon as you realize it?

1. Only worry about it once you reach your destination
2. Increase speed to minimize the time it remains extended
3. Stop safely as soon as possible and retract or correct the landing gear before continuing
4. Continue driving normally since the landing gear will retract fully back into position on its own

Question 14Not answered

Why is following distance especially important when driving a combination vehicle in heavy traffic?

1. It only matters on highways, not in city traffic
2. Combination vehicles stop just as quickly as ordinary passenger cars do in heavy stop-and-go traffic conditions
3. The added length and weight increase the total stopping distance needed compared to a single vehicle
4. Following distance rules do not apply to combination vehicles

Question 15Not answered

Why can two trailers with the same length but different wheelbase spacing off-track differently in the same turn?

1. Off-tracking depends only on the trailer's total length, never on where along it the axles happen to sit
2. Two trailers of the same length always off-track identically
3. The distance between the trailer's kingpin and its rear axles changes how far the rear wheels cut inside the tractor's path
4. Off-tracking is determined solely by tire brand

Question 16Not answered

Why does ABS not prevent a jackknife or rollover caused by taking a curve too fast?

1. ABS actively steers the vehicle through curves regardless of speed
2. ABS prevents all forms of rollover under any circumstance
3. ABS only functions when the vehicle is traveling in a straight line, which is why curves are unaffected by it
4. ABS addresses wheel lockup during braking, not the loss of control from excessive cornering speed alone

Question 17Not answered

Where is the tractor's own ABS malfunction lamp typically located, and what does it warn about?

1. There is no separate lamp for the tractor's ABS
2. On the trailer's rear only, warning of a tractor engine problem unrelated to braking
3. On the fuel gauge, warning of low fuel pressure
4. On the instrument panel, warning of a fault in the tractor's antilock system

Question 18Not answered

While walking around a combination vehicle, you notice a crack in one of the trailer's frame rails. What should you do?

1. Wrap the area with tape as a temporary reinforcement
2. Do not operate the trailer until a qualified mechanic evaluates and repairs the frame
3. Reduce the load slightly and continue the trip
4. Watch the crack over the trip and stop only if it visibly grows longer or wider than before

Question 19Not answered

What should you check about the rear underride guard on a trailer during a pre-trip inspection?

1. Nothing, since it has no real safety function and exists purely as a rear bumper style decoration
2. That it is polished to a shine
3. That it matches the trailer's paint color
4. That it is bent, cracked, or missing hardware that would weaken it in a rear collision

Question 20Not answered

Why should you connect the air lines and electrical connector before backing fully under the trailer in some coupling sequences, or immediately after in others, but never skip the step?

1. These connections only matter for the trailer's cargo, not its brakes or running lights
2. They can be connected at the destination instead of before driving
3. The trailer brakes and lights need these connections to function once coupled and moving
4. Air and electrical connections are optional if the trip is short

Question 21Not answered

If the trailer begins to sway noticeably at highway speed with no clear cause, what is a reasonable first response?

1. Accelerate to see if the sway resolves itself
2. Ease off the accelerator and prepare to pull over to inspect the trailer, tires, and load once safe to do so
3. Apply the trailer hand valve repeatedly and firmly until the sway eventually stops on its own
4. Ignore it since minor sway is never worth investigating

Question 22Not answered

What happens to a combination vehicle's braking if the ABS fails completely but the regular air brakes are undamaged?

1. The parking brake also automatically stops working entirely whenever the antilock braking system fails
2. The vehicle loses all braking ability immediately
3. The service brakes still work and stop the vehicle, but wheels can lock up under hard braking without ABS to prevent it
4. The engine automatically limits speed to compensate

Question 23Not answered

Why do you check that a trailer's conspicuity tape or reflectors are clean and visible during a pre-trip inspection?

1. Conspicuity markings exist only to satisfy a manufacturer sticker requirement, not to aid visibility
2. They have no real safety benefit, only a cosmetic one
3. They are relevant only when the trailer is parked, not while driving
4. They help other drivers see the length and outline of the trailer, especially at night

Question 24Not answered

Why is off-tracking a bigger factor for a double or triple combination than for a single trailer?

1. Off-tracking is identical regardless of the number of trailers
2. Additional trailers eliminate off-tracking entirely thanks to their own fully independent steering axles
3. Off-tracking decreases as more trailers are added to a combination
4. Additional trailers add more length and hinge points, which can increase how much the rearmost unit cuts the corner

Question 25Not answered

Your combination vehicle's trailer brakes fail while descending a grade. What should you do?

1. Immediately disconnect the trailer while moving
2. Continue at the same speed since the tractor brakes alone are more than enough to stop the whole loaded combination
3. Use the tractor's brakes and a low gear together, and look for an escape ramp or safe place to stop if needed
4. Shift into neutral to reduce strain on the brakes

Question 26Not answered

Since when have most tractors and trailers manufactured for use in combination been required to have anti-lock braking systems (ABS)?

1. ABS became required only after 2020
2. Since federal requirements phased in ABS for new tractors, trailers, and buses starting in the 1990s
3. It has been mandatory since the very first diesel tractors were built
4. ABS has always been standard equipment on every commercial vehicle ever built, going back decades before 1990

Question 27Not answered

What does the antilock braking system (ABS) on a combination vehicle help prevent?

1. The engine from stalling at idle
2. The need for regular brake maintenance, since ABS is designed to replace routine service checks
3. Wheel lockup during hard braking, which helps the driver keep steering control
4. The vehicle from exceeding its top speed

Question 28Not answered

If the trailer brakes lock and cause a trailer swing while driving a combination vehicle, what should the driver avoid doing?

1. Easing off the accelerator to let the trailer settle back into a straight line
2. Steering smoothly to maintain the tractor's path
3. Continuing to apply the trailer hand valve hard, which can worsen the swing
4. Watching the mirrors to track the trailer's movement

Question 29Not answered

When making a wide right turn at an intersection, why should you avoid swinging left into the next lane before turning right?

1. It is illegal everywhere regardless of the vehicle's size
2. It reduces off-tracking by giving the trailer a better angle to swing wide through the turn without cutting it
3. It invites other drivers to pass on the right and cut into the space your trailer's off-tracking wheels are about to occupy
4. It has no real downside as long as a turn signal is used

Question 30Not answered

What is the key difference between off-tracking and the rearward amplification (trailer sway) sometimes seen in combination vehicles?

1. Off-tracking only happens at high highway speed, while rearward amplification only happens when the vehicle is parked overnight
2. Off-tracking is a steady geometric effect of turning, while rearward amplification is a dynamic side-to-side motion that builds up from sudden steering
3. They are two names for the exact same effect
4. Rearward amplification is caused by tire pressure, while off-tracking is caused by weather