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Indiana CDL General Knowledge study materials
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Indiana CDL General Knowledge practice questions

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Question 1Vehicle Inspection

During a pre-trip inspection of a combination vehicle, where should you check the slack adjusters on a drum-brake axle?

  1. By pumping the brake pedal and watching the dashboard warning lamp
  2. Only at the tractor's front steer axle, since trailer brakes self-adjust
  3. Inside the brake drum after removing the wheel and hub assembly
  4. On the push rod side of each brake chamber, with the parking brake released and wheels chocked Correct answer.

Explanation

Slack adjusters are checked at the push rod with the vehicle secured and the parking brake released so the rod is free to move. You pull each adjuster by hand to confirm it does not move more than about one inch where the rod attaches. Wheels must be chocked so the vehicle cannot roll during the check.

Question 2Vehicle Inspection

What is the proper way to check the engine oil level during a pre-trip inspection?

  1. With the engine running so oil is circulating
  2. Immediately after a long drive without waiting
  3. By watching the oil pressure gauge only
  4. With the engine off and the vehicle level, using the dipstick Correct answer.

Explanation

Oil level is read from the dipstick with the engine off and the vehicle on level ground so the reading reflects the true sump level. Checking while running or on a slope gives a false reading and can lead to overfilling or missing a leak. The pressure gauge tells you about operating pressure, not the quantity of oil present.

Question 3Vehicle Inspection

When inspecting a tire on your tractor, you find a cut in the tread that reaches the fabric. What should you do?

  1. Reduce speed and recheck the tire at the next stop
  2. Cover it with a tread-depth gauge reading and pass the tire
  3. Remove the vehicle from service until the tire is replaced Correct answer.
  4. Note it on the report and continue the trip if pressure holds

Explanation

A cut that exposes the fabric means the tire's structural cords are damaged and the tire can fail under load. Tires with fabric exposed are out of service and must be replaced before the vehicle is dispatched. Holding air pressure does not make the tire safe.

Question 4Vehicle Inspection

How much steering wheel free play is generally acceptable before you should question the steering system?

  1. Any free play at all
  2. More than about 10 degrees Correct answer.
  3. More than about 45 degrees
  4. More than about 90 degrees

Explanation

Steering free play is measured with the front wheels straight ahead and the vehicle stationary. More than roughly 10 degrees of movement at the rim before the wheels respond can indicate worn linkage or a loose gear box. Larger amounts are clearly excessive and unsafe.

Question 5Vehicle Inspection

While checking the air brake system, the low air pressure warning should activate before pressure drops below what level?

  1. 10 psi
  2. 60 psi Correct answer.
  3. 90 psi
  4. 30 psi

Explanation

The low air pressure warning device must come on before air pressure falls below 60 psi. This gives the driver advance notice that braking performance is being lost. A warning that waits until lower pressure leaves too little margin to stop safely.

Question 6Vehicle Inspection

During the pre-trip inspection you check the coupling system. Which item confirms the trailer kingpin is locked into the fifth wheel?

  1. The trailer air supply valve position
  2. The height of the trailer landing gear
  3. The color of the glad hands
  4. The pull test with the tractor brakes released and trailer brakes set Correct answer.

Explanation

After coupling, you pull forward gently with the trailer brakes set and the tractor brakes released. If the kingpin is not locked, the trailer will not hold and the tractor will pull out from under it. This tug test verifies the locking jaws have closed around the kingpin.

Question 7Vehicle Inspection

What should you do with the wheels before crawling under a vehicle during a pre-trip inspection?

  1. Turn the steering to full lock
  2. Leave the engine idling in gear
  3. Remove the valve cores to release air
  4. Chock them and set the parking brake Correct answer.

Explanation

Chocking the wheels and setting the parking brake prevent the vehicle from rolling while you are underneath. This is a basic safety step before any inspection that puts you below the vehicle. Leaving the engine running or in gear adds risk rather than reducing it.

Question 8Vehicle Inspection

You are inspecting the exhaust system on a diesel tractor. Which finding requires the vehicle to be placed out of service?

  1. Minor soot at the tailpipe outlet
  2. Surface rust on the muffler body
  3. A crack in the exhaust pipe ahead of the muffler that leaks into the cab area Correct answer.
  4. A loose heat shield that still covers the component

Explanation

Exhaust leaks located where fumes can enter the cab expose the driver to carbon monoxide and are a serious defect. A cracked pipe ahead of the muffler near the cab is an out-of-service condition until repaired. Cosmetic rust and normal soot at the outlet are not safety defects.

Question 9Vehicle Inspection

When checking the lights on a tractor-trailer, what is the purpose of turning on the four-way flashers during the walk-around?

  1. To check the headlight aim
  2. To test the battery charge level
  3. To confirm all turn signal and hazard lamps flash on both tractor and trailer Correct answer.
  4. To verify the alternator output

Explanation

Hazard flashers energize the turn signal bulbs at all four corners of the tractor and along the trailer. Walking around while they flash lets you confirm each lamp works and that trailer wiring is connected properly. This is a fast way to catch a burned-out bulb or a bad connection.

Question 10Vehicle Inspection

What does the build-up rate test on an air brake system check?

  1. How quickly the brakes release after application
  2. How fast the compressor raises pressure from 85 to 100 psi Correct answer.
  3. The amount of air lost through the slack adjusters
  4. The pressure held in the trailer supply line

Explanation

The build-up test measures how quickly the compressor restores pressure, typically from 85 to 100 psi, with the engine at operating rpm. A slow build-up suggests a weak compressor, a leak, or a governor problem. It is a required part of the air brake inspection.

Question 11Vehicle Inspection

During the walk-around you notice the trailer's rear impact guard is bent upward and no longer at the required height. How should you treat this?

  1. A defect that must be corrected before operating Correct answer.
  2. Acceptable on empty trailers only
  3. Acceptable if the trailer lights still work
  4. Normal wear that needs no attention

Explanation

The rear impact guard protects other vehicles from underriding the trailer in a collision and must be intact and at the proper height. A bent or missing guard is a defect that must be repaired before the vehicle is used. Load status does not change the requirement.

Question 12Vehicle Inspection

What is the correct procedure for checking the coolant level on a vehicle with a see-through surge tank?

  1. Check only when the low coolant light comes on
  2. Remove the radiator cap while the engine is hot
  3. Read the level against the tank markings with the engine cool Correct answer.
  4. Overfill the tank to the top to be safe

Explanation

A see-through surge tank lets you check coolant without opening the pressurized cap. Read the level against the hot and cold markings while the engine is cool. Never remove a radiator cap on a hot engine, because scalding coolant can erupt.

Question 13Vehicle Inspection

You are checking the drive belts on the engine. Which condition means the belt must be replaced?

  1. A belt with cracks, glazing, or frayed edges Correct answer.
  2. A belt that is properly seated in the pulley grooves
  3. A belt with a small amount of surface dust
  4. A belt with more than about 3/4 inch of deflection at the longest span

Explanation

Cracks, glazing, and frayed edges show the belt is deteriorating and may fail on the road. Glazing also reduces grip and can cause slippage and overheating. Deflection is a tension check, not a replacement criterion by itself.

Question 14Vehicle Inspection

When inspecting the fifth wheel, which condition should be reported?

  1. Missing or loose mounting bolts Correct answer.
  2. A light film of grease on the locking jaws
  3. A properly seated release handle with the safety latch closed
  4. Normal wear polish on the top plate

Explanation

Loose or missing mounting bolts can let the fifth wheel separate from the tractor frame under load. This is a critical defect that must be repaired before operation. Grease, a latched handle, and polished wear surfaces are all normal.

Question 15Vehicle Inspection

How should you test the service brakes during a pre-trip inspection?

  1. By checking the pedal height against the seat
  2. With the vehicle moving slowly in a safe area, apply the brakes and check for pull or delay Correct answer.
  3. By setting the trailer spring brakes only
  4. By pressing the pedal while parked and listening for air

Explanation

A service brake test is done at low speed in a safe area, applying the brakes and noting any pull to one side, unusual delay, or noise. This confirms the brakes actually stop the vehicle evenly. A parked pedal check alone does not reveal uneven braking.

Question 16Vehicle Inspection

What does an air compressor governor do in an air brake system?

  1. It stores air for emergency braking
  2. It releases air from the trailer supply line
  3. It controls when the compressor loads and unloads to maintain pressure Correct answer.
  4. It adjusts the slack adjusters automatically

Explanation

The governor senses system pressure and cycles the compressor between its cut-in and cut-out settings. This keeps air pressure within the operating range instead of letting it climb indefinitely or fall too low. Storage, supply line release, and slack adjustment are handled by other components.

Question 17Vehicle Inspection

During the inspection you find the battery box is loose and the hold-down is missing. Why is this a safety concern?

  1. It affects the headlight aim
  2. Vibration can damage the battery and cause a short or fire Correct answer.
  3. It changes the alternator output
  4. It reduces tire tread depth

Explanation

Batteries must be secured so vibration and shocks do not crack the case, loosen terminals, or let the battery shift into other components. A loose battery can short against metal and start a fire. A proper hold-down is part of the required inspection.

Question 18Vehicle Inspection

You are checking the glad hands and trailer air lines. Which condition requires attention before dispatch?

  1. A trailer air line with a visible cut or chafed spot exposing the inner layer Correct answer.
  2. Couplers locked together with their shutoff valves open
  3. Lines routed with slack to allow turning
  4. Couplers with fresh rubber seals and no leaks

Explanation

Air lines that are cut or chafed can burst or leak, causing a loss of trailer brakes or an emergency brake application. Damaged lines must be replaced before the vehicle is operated. Good seals, proper routing, and locked couplers with valves open are correct conditions.

Question 19Vehicle Inspection

What is the purpose of the leak-down test in an air brake pre-trip inspection?

  1. To confirm the system holds pressure without excessive loss when fully charged and the engine off Correct answer.
  2. To check the trailer spring brake release time
  3. To measure how quickly the compressor builds pressure
  4. To test the parking brake holding power on a grade

Explanation

With the system fully charged and the engine off, you watch the gauges to see how much pressure is lost over time. Excessive loss indicates a leak that could leave you without enough air to brake. It is separate from the build-up and applied-leak tests.

Question 20Vehicle Inspection

During a pre-trip inspection you notice the left front wheel seal is leaking grease onto the brake drum. What is the correct action?

  1. Wipe the drum clean and continue the trip
  2. Reduce trailer load and proceed
  3. Report the defect and place the vehicle out of service until repaired Correct answer.
  4. Adjust the slack adjuster to compensate

Explanation

Grease or oil on brake linings or drums reduces friction and can cause the brake to grab or fail on that wheel. A leaking wheel seal is a defect that must be repaired before the vehicle is used. Wiping the surface does not restore contaminated linings.

Question 21Basic Control of Your Vehicle

When you must drive at a speed below the posted minimum on a limited-access highway, what does Indiana law require you to do?

  1. Drive in the left lane so faster traffic can pass on the right
  2. Move to the right lane and keep as close as possible to the right edge Correct answer.
  3. Stop on the shoulder until traffic clears, then resume speed
  4. Turn on your four-way flashers and continue at the slow speed

Explanation

A vehicle moving slower than the normal flow of traffic must be driven in the right-hand lane or as close to the right edge as practical. This keeps slow-moving vehicles out of the path of faster traffic and reduces the closing-speed difference that causes rear-end crashes. Flashers do not authorize driving below the posted minimum speed.

Question 22Basic Control of Your Vehicle

You are driving a tractor-trailer on a two-lane road and want to pass a slower vehicle. Which condition must exist before you begin the pass?

  1. There is no oncoming traffic visible for at least one mile
  2. The vehicle ahead signals that it is safe for you to pass
  3. Your engine can accelerate the rig to at least the posted limit
  4. The passing zone is long enough for your entire unit to clear before oncoming traffic arrives Correct answer.

Explanation

A heavy combination vehicle needs far more time and distance to complete a pass than a car does. You should begin a pass only when the clear passing zone lets your whole unit return to the right lane before any oncoming vehicle could reach you. A signal from the driver ahead cannot guarantee that oncoming traffic is clear.

Question 23Basic Control of Your Vehicle

What is the proper way to hold the steering wheel when driving a large commercial vehicle?

  1. Both hands on opposite sides of the wheel, near the nine and three o'clock positions Correct answer.
  2. Both hands on the inside of the wheel rim near the top
  3. One hand at the top, with the other resting on the shift lever
  4. Both hands at the bottom of the wheel for leverage

Explanation

Holding the wheel with both hands on opposite sides gives the best control and lets you turn quickly in an emergency. Keeping your hands and thumbs outside the rim also reduces the risk of injury if the wheel is jerked by a tire failure or rough pavement.

Question 24Basic Control of Your Vehicle

Why should you avoid making quick lane changes in a loaded tractor-trailer?

  1. The high center of gravity and rearward weight shift can cause a rollover or loss of control Correct answer.
  2. Quick steering inputs will cause the engine to shut down
  3. The trailer brakes apply automatically during sharp steering
  4. The transmission will not shift during a rapid maneuver

Explanation

A loaded rig carries a high center of gravity, so a sudden steering input shifts weight outward and can lift the inside wheels. Abrupt lane changes also produce trailer sway and can lead to a rollover. Smooth, gradual steering inputs keep the load settled.

Question 25Basic Control of Your Vehicle

You are about to back a tractor-trailer to the left. Which procedure is correct?

  1. Turn the wheel sharply left and hold it there until the trailer is in place
  2. Turn the wheel to the right, then follow the trailer with the steering wheel
  3. Keep the wheel straight and let the trailer track on its own
  4. Turn the wheel to the left, then turn it back the other way as the trailer moves Correct answer.

Explanation

To back left, turn the steering wheel left to start the trailer moving that way, then reverse the wheel as the trailer comes around so the tractor follows. Backing a combination vehicle requires constant small corrections rather than one fixed steering position. Always back slowly and use a spotter when possible.

Question 26Basic Control of Your Vehicle

When backing any commercial vehicle, what is the safest practice if you cannot see behind the unit?

  1. Rely on the mirrors alone and continue slowly
  2. Sound the horn continuously and keep backing
  3. Use a helper as a spotter and stop if you lose sight of that person Correct answer.
  4. Back quickly to minimize the time spent in reverse

Explanation

If you cannot see behind the vehicle, use a helper who stays in view in your mirror and signals you. Stop immediately if you lose sight of the spotter, because that person may have moved into a blind area. Mirrors alone do not cover every blind spot behind a large vehicle.

Question 27Basic Control of Your Vehicle

You are driving a bus and must stop to unload passengers on a two-lane road. How should you position the vehicle?

  1. In the traffic lane, with the four-way flashers on and doors open
  2. Angled partly into the lane to discourage passing
  3. In the left lane so passengers can cross behind the bus
  4. As far to the right as practical, off the traveled portion where possible, before opening the door Correct answer.

Explanation

Pull as far to the right as you can so passengers step away from moving traffic and following vehicles have room to pass. Signal your stop early and activate your hazard flashers to warn traffic behind you. Never unload passengers into a live lane.

Question 28Basic Control of Your Vehicle

What is the correct way to use the accelerator and clutch to start a heavy manual-transmission truck moving from a stop?

  1. Ease out the clutch while applying steady light throttle Correct answer.
  2. Hold the clutch partly engaged and rev the engine high
  3. Release the clutch fully, then apply heavy throttle
  4. Shift to a higher gear before releasing the clutch

Explanation

Smooth starts come from a steady, light throttle combined with a gradual clutch release so the engine does not stall or the vehicle lurch. Releasing the clutch fully before adding power causes stalling or hopping. High engine speed while slipping the clutch causes excessive wear.

Question 29Basic Control of Your Vehicle

Which statement correctly describes how to brake a tractor-trailer on a long downgrade?

  1. Select a lower gear before the grade and use engine braking with light, steady brake applications Correct answer.
  2. Shift to neutral and rely on the service brakes
  3. Use the trailer hand valve to control speed down the grade
  4. Apply the brakes hard and continuously to hold a steady speed

Explanation

Selecting a lower gear before the descent lets engine braking control speed and reduces heat buildup in the service brakes. Use light, steady pedal pressure and avoid riding the brakes continuously. Coasting in neutral removes engine braking and is dangerous.

Question 30Basic Control of Your Vehicle

What does the term 'controlled braking' mean when you must stop quickly in a vehicle without ABS?

  1. Using the parking brake together with the foot brake
  2. Pumping the pedal rapidly on and off
  3. Pressing the pedal as hard as possible and holding it
  4. Applying the brakes firmly without locking the wheels, allowing steering control Correct answer.

Explanation

Controlled braking means applying firm pressure up to the point just before the wheels lock, so you can still steer while slowing. Locked wheels cause a skid and remove steering control. This technique gives the shortest stop while keeping the vehicle pointed where you want it.

Question 31Basic Control of Your Vehicle

Your vehicle begins to skid on a wet road. What should you do first?

  1. Release the brake and steer in the direction you want to go Correct answer.
  2. Turn the wheel sharply opposite the skid
  3. Accelerate to pull the vehicle straight
  4. Brake hard to transfer weight to the front

Explanation

If the wheels are locked, release the brake so they can roll and regain traction, then steer where you want to go. Steering into the direction you want the front of the vehicle to travel helps the tires regain grip. Hard braking or sharp counter-steering will worsen the skid.

Question 32Basic Control of Your Vehicle

How can you tell that you are driving too fast for conditions on a wet road?

  1. The steering feels light and the tires hiss on the pavement Correct answer.
  2. You need to use the brakes more often than usual
  3. Other vehicles are passing you
  4. The engine runs at a higher RPM than normal

Explanation

A light, floating feeling in the steering and a hissing or splashing sound from the tires are signs of hydroplaning, meaning the tires have lost contact with the road. When that happens, ease off the accelerator and avoid hard braking until grip returns. Reducing speed below the hydroplaning threshold is the best prevention.

Question 33Basic Control of Your Vehicle

When driving through a curve, what is the recommended technique for a large vehicle?

  1. Shift to neutral to reduce engine drag in the curve
  2. Maintain speed and steer sharply through the apex
  3. Slow down before entering the curve and accelerate gently after the midpoint Correct answer.
  4. Brake firmly while in the middle of the curve

Explanation

Reduce speed before the curve while the vehicle is still traveling straight, then apply gentle power as you pass the midpoint and exit. Braking in a curve shifts weight and reduces tire grip, which can cause a skid or rollover in a tall vehicle. Coasting in neutral removes engine control.

Question 34Basic Control of Your Vehicle

A traffic light turns yellow as your loaded truck approaches an intersection at the posted speed. What is the safest action?

  1. Accelerate hard to clear the intersection before the light turns red
  2. Brake firmly and stop if you can do so safely; otherwise proceed through with caution Correct answer.
  3. Sound the horn and continue at the same speed
  4. Swerve into the adjacent lane to avoid stopping

Explanation

A loaded truck needs far more distance to stop than a car, so you must judge whether you can stop safely before the stop line. If you cannot stop without skidding or entering the intersection, continue through carefully rather than brake abruptly. Hard acceleration or swerving creates a greater hazard.

Question 35Basic Control of Your Vehicle

What is the proper procedure for shifting a manual transmission when climbing a hill with a heavy load?

  1. Shift up early to keep engine RPM low
  2. Shift down before the engine lugs, keeping RPM in the power band Correct answer.
  3. Hold the clutch in while the truck climbs
  4. Skip gears to reduce shifting time

Explanation

On a climb, shift to a lower gear before the engine starts to lug so you stay in the engine's power range. Waiting until the engine bogs down may leave you unable to complete the downshift. Keeping the clutch depressed or skipping gears risks losing momentum and control.

Question 36Basic Control of Your Vehicle

Why should you check your mirrors systematically while driving?

  1. To confirm that your trailer is tracking properly and to monitor blind spots Correct answer.
  2. To estimate fuel consumption
  3. To check the color of the traffic light behind you
  4. To decide when to change the radio station

Explanation

Regular mirror checks let you verify that the trailer is tracking correctly, watch for vehicles in your blind spots, and spot tire or load problems early. They also give you time to react before a lane change or stop. Mirror checks should be frequent and brief so your eyes return to the road quickly.

Question 37Basic Control of Your Vehicle

You are driving at night and an oncoming vehicle's high beams glare into your eyes. What should you do?

  1. Turn on your dome light to reduce the glare
  2. Look directly at the headlights to judge the distance
  3. Flash your high beams repeatedly in response
  4. Look toward the right edge of your lane and slow down Correct answer.

Explanation

Looking toward the right edge of your lane keeps you on course while avoiding the glare. Slow down because the glare reduces your ability to see hazards ahead. Flashing your lights back or staring at the source makes the glare worse.

Question 38Basic Control of Your Vehicle

When must you use your headlights in Indiana?

  1. Only on rural roads without streetlights
  2. Only between midnight and sunrise
  3. From sunset to sunrise, and whenever weather or visibility requires them Correct answer.
  4. Only when other vehicles are present

Explanation

Indiana requires headlights from sunset to sunrise and any time conditions such as rain, fog, or snow make it hard to see or be seen. Many drivers also turn them on whenever windshield wipers are needed. Headlights help other drivers see you as much as they help you see the road.

Question 39Basic Control of Your Vehicle

What is the correct way to use your horn when driving a commercial vehicle?

  1. To express frustration at another driver's mistake
  2. Continuously in heavy traffic to clear a path
  3. To announce your arrival at a delivery site
  4. Only as a warning of danger, such as a vehicle drifting into your lane Correct answer.

Explanation

The horn is a safety device used to warn others of danger, such as a vehicle drifting toward you or a pedestrian stepping into the road. Using it to vent frustration or to force traffic aside can startle drivers and cause crashes. Some communities also restrict horn use except for emergencies.

Question 40Basic Control of Your Vehicle

Which of these is a sign that your brakes may be fading on a long mountain descent?

  1. The pedal feels firmer than usual
  2. The engine temperature gauge drops
  3. The pedal travels farther and the vehicle slows less for the same pressure Correct answer.
  4. The steering wheel becomes easier to turn

Explanation

Brake fade occurs when overheated drums and linings lose friction, so the pedal may sink and the vehicle responds less to the same pressure. If you notice fade, downshift to a lower gear and use engine braking to reduce speed. Pulling over to let the brakes cool is the safest response if fade continues.

Question 41Shifting Gears

In a typical unsynchronized heavy-duty manual transmission, what must happen before the sliding gear or collar can engage the next gear without clashing?

  1. Engine speed must be increased to the governor limit
  2. Transmission input shaft speed must match the gear being engaged Correct answer.
  3. Vehicle must be rolling faster than the target gear allows
  4. Clutch pedal must be released fully

Explanation

Non-synchronized truck transmissions require the driver to match the speed of the transmission input shaft to the speed of the gear being selected. This is done by double-clutching or by timing the shift within the engine and road speed range. Without a match, the engaging teeth clash and the gear cannot slide in.

Question 42Shifting Gears

When double-clutching to upshift in a truck without synchronized gears, what is the correct sequence after you move the shift lever to neutral?

  1. Press the clutch twice rapidly while keeping the throttle wide open
  2. Release the clutch, let engine speed drop, press the clutch again, then shift Correct answer.
  3. Hold the clutch down, race the engine, then shift
  4. Release the clutch and immediately shift without pressing it again

Explanation

Double-clutching on an upshift means pressing the clutch, shifting to neutral, releasing the clutch so the input shaft slows with the engine, then pressing the clutch again and engaging the next gear. Letting engine speed fall while in neutral brings the input shaft down to the speed of the higher gear.

Question 43Shifting Gears

Why do you briefly raise engine rpm while in neutral when double-clutching to downshift?

  1. To reduce the clutch pedal free play
  2. To make the exhaust brake engage
  3. To cool the transmission lubricant
  4. To speed up the input shaft so it matches the lower gear Correct answer.

Explanation

On a downshift the lower gear turns faster than the current gear, so the input shaft must be sped up to match it. Bumping the throttle in neutral with the clutch released spins the input shaft up to the required speed. This lets the lower gear engage without clashing.

Question 44Shifting Gears

Which practice best protects the clutch and transmission when starting a loaded tractor-trailer on a level surface?

  1. Select the proper low starting gear and release the clutch smoothly as you apply throttle Correct answer.
  2. Start in a high gear and slip the clutch until the truck rolls
  3. Hold the clutch partially engaged while revving the engine to the governor
  4. Release the clutch quickly while idling in a tall gear

Explanation

A loaded rig should be started in the gear that lets it move without stalling, with the clutch released progressively as throttle is applied. This limits clutch slippage and heat. Starting in too high a gear forces long slipping and can damage the clutch.

Question 45Shifting Gears

A driver downshifts from 7th to 6th at highway speed and the transmission grinds. What is the most likely cause?

  1. The exhaust brake was left on
  2. The shift was made too far below the governed speed
  3. The engine rpm was not raised enough to match the lower gear Correct answer.
  4. The clutch was pressed too slowly

Explanation

Grinding on a downshift in an unsynchronized transmission usually means the input shaft is turning slower than the lower gear requires. The driver must raise engine rpm in neutral, with the clutch released, so the input shaft speeds up to match. Insufficient rpm matching produces clashing teeth.

Question 46Shifting Gears

What is the purpose of progressive shifting in a heavy truck?

  1. To keep engine rpm above the torque peak at all times
  2. To run every gear to governed rpm before upshifting
  3. To skip every other gear regardless of load
  4. To upshift at the lowest rpm that still pulls the load, saving fuel and wear Correct answer.

Explanation

Progressive shifting means operating each gear only as high as needed to pull the load and then upshifting, keeping the engine in its efficient range. It reduces fuel use, noise, and engine wear compared with winding out every gear. Load and grade determine how high the rpm must go before the next upshift.

Question 47Shifting Gears

On a steep downgrade, which gear should you select before starting the descent?

  1. The same gear you used to climb the grade
  2. A gear low enough that engine braking holds the speed you want Correct answer.
  3. Neutral to save fuel
  4. The highest gear the truck will hold without braking

Explanation

The safe gear for a downgrade is one low enough that engine braking, with the exhaust brake if equipped, controls speed without riding the service brakes. You should select it before the descent and stay in it. This prevents brake fade from continuous application.

Question 48Shifting Gears

A driver needs to slow from 55 mph to about 35 mph for a work zone in a 10-speed unsynchronized transmission. What is the best technique?

  1. Coast in neutral until the speed drops, then shift directly into the gear for 35 mph
  2. Apply the exhaust brake only and leave the transmission in high gear
  3. Hold the clutch down and shift through the gears without releasing it
  4. Brake to the target speed, then downshift through the gears using double-clutching to keep engine rpm matched Correct answer.

Explanation

The driver should use the brakes to reach the target speed and then downshift one gear at a time with proper rpm matching so the truck stays in the correct gear for that speed. This keeps engine braking available and avoids lugging or over-revving. Coasting or skipping several gears risks losing control and gear damage.

Question 49Shifting Gears

What does it mean if the engine lugs after you upshift?

  1. Engine rpm is too low for the gear selected and the engine is straining Correct answer.
  2. The exhaust brake is automatically engaged
  3. Engine rpm is too high for the gear selected
  4. The clutch is fully released and the gear is correct

Explanation

Lugging occurs when engine rpm drops too low for the load in the selected gear, so the engine strains and cannot pull smoothly. The remedy is to downshift to a gear that brings rpm back into the power band. Continuing to lug can damage the engine and driveline.

Question 50Shifting Gears

A driver must climb a long grade with a heavy load in a 13-speed transmission. Which shifting strategy keeps the truck moving without over-revving or stalling?

  1. Run at governed rpm in each gear and skip two gears at a time
  2. Stay in the highest gear possible and let road speed drop until the engine lugs
  3. Downshift before rpm falls out of the power band so each gear pulls steadily Correct answer.
  4. Shift up early to keep rpm low, then hold that gear to the top

Explanation

On a climb the driver should downshift before rpm drops below the power band, so the engine stays in a range where it can pull the load. Waiting until the engine lugs risks a stall or a missed shift. Each gear should be used to keep steady progress up the grade.