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Maine CDL General Knowledge study materials
Maine CDL General Knowledge study resources

Maine CDL General Knowledge practice questions

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Question 1Vehicle Inspection

During a pre-trip inspection, you check the slack adjusters on a vehicle with automatic slack adjusters. What should you do if a push rod stroke exceeds the adjustment limit?

  1. Ignore it as long as the low air pressure warning buzzer still sounds
  2. Pump the brakes several times to reset the adjuster, then release the parking brake
  3. Tag the vehicle out of service and have the brake system repaired Correct answer.
  4. Drive normally because automatic adjusters always correct themselves once the brakes warm up

Explanation

An excessive push rod stroke means the brake chamber cannot apply full force to the foundation brake, so braking performance is compromised. Automatic slack adjusters are not a substitute for maintenance, and a vehicle with a stroke beyond the limit must not be placed in service until repaired. The defect is a brake-system violation that keeps the vehicle out of service.

Question 2Vehicle Inspection

How much air pressure loss is allowed during a static leak test of the air brake system with the engine off and the brakes released?

  1. No more than 3 psi in one minute Correct answer.
  2. No more than 10 psi in one minute
  3. Any loss is acceptable as long as the compressor keeps up
  4. No more than 2 psi in five minutes

Explanation

With a fully charged system, the engine off, and the brakes released, leakage should not exceed 3 psi in one minute for a single vehicle. A greater drop points to a leak that must be found and fixed before driving. With the brakes applied, the allowable loss is slightly higher.

Question 3Vehicle Inspection

While inspecting a tractor-trailer, you find a crack in a brake drum. What is the correct action?

  1. Place the vehicle out of service until the drum is replaced Correct answer.
  2. Continue the trip if the crack runs along the drum's edge rather than across the friction surface
  3. Continue the trip if the crack is shorter than one inch
  4. Note the crack and recheck it at the next scheduled service

Explanation

Any crack in a brake drum is a defect that can cause the drum to fail or the lining to grab unevenly, so the vehicle must be taken out of service. Cracks do not heal and can grow quickly under heat and stress. The drum must be replaced before the vehicle is driven.

Question 4Vehicle Inspection

You are checking tire condition during a pre-trip inspection. Which finding requires the vehicle to be placed out of service?

  1. A front tire with a tread depth of 3/32 inch Correct answer.
  2. A tire with a valve stem cap missing
  3. A rear tire with a tread depth of 3/32 inch
  4. A tire with a small cut in the sidewall that does not expose cord

Explanation

Steering axle tires must have at least 4/32 inch of tread depth, so a front tire at 3/32 inch is below the minimum and is a defect. All other tires on the vehicle must have at least 2/32 inch. A missing valve cap or a shallow cut that does not expose cord is not by itself an out-of-service condition.

Question 5Vehicle Inspection

What is the correct way to test the service brakes during a pre-trip inspection?

  1. Set the parking brake and try to drive forward to see if the vehicle moves
  2. Release the parking brake, drive slowly forward, apply the brakes firmly, and check that the vehicle stops without pulling to one side Correct answer.
  3. With the engine off, press the brake pedal and listen for air leaks
  4. Pump the brake pedal five times while parked and watch the air gauge

Explanation

The service brake test is a moving test: at low speed, the brakes should stop the vehicle smoothly and in a straight line. Pulling to one side, a spongy pedal, or a delayed stop indicates a problem. Static pedal and parking brake checks are separate parts of the inspection.

Question 6Vehicle Inspection

During the parking brake test, you set the parking brake and gently try to move the vehicle. What result indicates the parking brake is working properly?

  1. The vehicle rolls slowly forward
  2. The low air pressure warning sounds
  3. The vehicle does not move Correct answer.
  4. The engine stalls immediately

Explanation

A properly functioning parking brake should hold the vehicle stationary when you try to pull away. If the vehicle moves, the parking brake is not holding and must be repaired. The engine stalling or a warning buzzer is not the pass criterion.

Question 7Vehicle Inspection

You are inspecting the coupling system on a tractor-trailer. Which condition means the trailer is not properly secured?

  1. The locking jaws are open around the kingpin Correct answer.
  2. The trailer apron rests flat on the fifth wheel
  3. The fifth wheel is greased
  4. The release handle is in the locked position

Explanation

The locking jaws must fully close around the kingpin to hold the trailer. If the jaws are open, the trailer can separate from the tractor. Properly greased, locked, and seated components are normal and desirable.

Question 8Vehicle Inspection

When inspecting the air lines between the tractor and trailer, what should you check?

  1. That the lines are disconnected so air can escape
  2. That the lines are not cracked, cut, or tangled and are properly connected Correct answer.
  3. That the lines are tied together tightly with no slack
  4. That the lines are wrapped around the fifth wheel for storage

Explanation

Air lines must be free of cracks, cuts, and chafing, and they must be securely connected with no leaks. They should have enough slack to allow turns without pulling apart, but not so much that they drag or tangle. Damaged or tangled lines can cause air loss and brake failure.

Question 9Vehicle Inspection

During the walk-around inspection, you notice that the emergency (spring) brakes on the trailer have not been released. What should you do?

  1. Pull the trailer air supply valve out and leave it out
  2. Charge the trailer air system and push in the trailer air supply valve to release the spring brakes Correct answer.
  3. Drive the vehicle slowly until the brakes release on their own
  4. Disconnect the emergency air line to release the brakes

Explanation

Spring brakes apply when air pressure is lost and release when the system is charged and the supply valve is pushed in. The tractor must build air pressure and the trailer valve must be in the normal (in) position. Driving with spring brakes applied or disconnecting lines will not safely release them.

Question 10Vehicle Inspection

What should you check about the exhaust system during a pre-trip inspection?

  1. That it is painted with heat-resistant paint
  2. That it is disconnected to prevent carbon monoxide buildup
  3. That it is secure, undamaged, and not leaking Correct answer.
  4. That it is routed through the cab for warmth

Explanation

A loose or leaking exhaust system can allow carbon monoxide into the cab and is a safety hazard. The system must be securely mounted, free of cracks, and not leaking. Routing exhaust into the cab or disconnecting it is dangerous.

Question 11Vehicle Inspection

You are checking the steering system. Which finding is a defect that must be corrected before driving?

  1. A power steering reservoir at the full mark
  2. A steering box that is securely mounted
  3. A steering wheel that turns smoothly
  4. More than 10 degrees of free play at the steering wheel Correct answer.

Explanation

Excessive steering wheel free play means the steering linkage is worn or loose, reducing control. Free play should generally not exceed about 10 degrees. Smooth operation, a full reservoir, and a secure steering box are all normal.

Question 12Vehicle Inspection

During a pre-trip inspection, you check the suspension. Which condition is acceptable?

  1. A cracked leaf spring
  2. A leaf spring with a slightly loose but intact U-bolt Correct answer.
  3. A broken spring hanger
  4. A missing leaf spring

Explanation

A slightly loose but intact U-bolt is not ideal and should be checked, but a cracked, missing, or broken spring component is a clear defect. Cracked or missing leaves and broken hangers can cause loss of control and are out-of-service conditions. Intact suspension parts are what the inspection is looking for.

Question 13Vehicle Inspection

What is the purpose of checking the slack adjusters during a pre-trip inspection?

  1. To confirm the brakes are properly adjusted and will apply fully Correct answer.
  2. To test the parking brake cable
  3. To check the tire pressure
  4. To verify the engine oil level

Explanation

Slack adjusters connect the brake chamber push rod to the slack adjuster arm and keep the brake shoes close to the drum. Checking them confirms the brakes are in adjustment and will apply with full force. They have nothing to do with tires, engine oil, or parking brake cables.

Question 14Vehicle Inspection

While inspecting the lights, you find that the trailer's turn signals do not work but the tractor's signals do. What should you do?

  1. Continue because only the tractor's signals are required
  2. Use hand signals instead of the trailer lights
  3. Drive during daylight only to avoid the problem
  4. Repair the trailer light circuit before driving Correct answer.

Explanation

Turn signals on the trailer are required equipment, and a failure means the vehicle is not safe or legal to operate. The circuit must be repaired before the trip. Daylight driving or hand signals do not substitute for required trailer lights.

Question 15Vehicle Inspection

During the air brake check, you build pressure to the governor cut-out, then turn off the engine. What should you do next to test for leaks?

  1. Watch the air gauge for one minute with the brakes released, then apply the brakes and watch for another minute Correct answer.
  2. Pump the brake pedal rapidly and listen for the compressor to restart
  3. Drain all air from the system and check that the warning buzzer sounds
  4. Release the parking brake and drive slowly while watching the gauge

Explanation

The static leak test is done with the system fully charged and the engine off. First check leakage with the brakes released, then with the brakes applied, comparing each to the allowable limits. Driving or draining the system does not measure static leakage.

Question 16Vehicle Inspection

You are inspecting a vehicle with hydraulic brakes. Which condition indicates a problem?

  1. The brake pedal feels spongy and sinks toward the floor Correct answer.
  2. The brake pedal is firm and holds pressure
  3. The brake warning light is off after the engine starts
  4. The brake fluid is at the full mark

Explanation

A spongy pedal that sinks indicates air in the hydraulic system or a fluid leak, both of which reduce braking force. A firm pedal, proper fluid level, and a warning light that goes out are normal. Hydraulic brake defects must be repaired before driving.

Question 17Vehicle Inspection

What should you check about the windshield and wipers during a pre-trip inspection?

  1. That the windshield is tinted dark for glare
  2. That the wipers are removed to prevent scratching
  3. That the windshield is clean and free of cracks and the wipers work Correct answer.
  4. That the windshield washer fluid is empty

Explanation

A clean, uncracked windshield and working wipers are required for visibility. Cracks in the driver's view and inoperative wipers are defects. Dark tint, removed wipers, or an empty washer reservoir reduce visibility and are not acceptable.

Question 18Vehicle Inspection

During a pre-trip inspection, you find that the emergency exit door on a bus does not open freely. What is the correct action?

  1. Ask passengers to use the emergency door only in an emergency
  2. Continue if the regular door works
  3. Tape the door shut and continue the route
  4. Place the bus out of service until the door is repaired Correct answer.

Explanation

Emergency exits must open freely so passengers can escape in a crash or fire. A door that does not open is a serious safety defect and the bus must not be used until it is fixed. The regular door working does not make up for a blocked emergency exit.

Question 19Vehicle Inspection

What should you check about the cargo securement before driving?

  1. That the cargo is properly distributed and secured with adequate tiedowns Correct answer.
  2. That the cargo is left unsecured so it can settle
  3. That the tiedowns are loose enough to allow shifting
  4. That the cargo is loaded as high as possible

Explanation

Cargo must be distributed within weight limits and secured so it cannot shift or fall. Loose or missing tiedowns can cause a crash or loss of control. Loading high, leaving tiedowns loose, or leaving cargo unsecured all increase risk.

Question 20Vehicle Inspection

You are checking the mirrors on a commercial vehicle. Which condition is acceptable?

  1. The mirrors are clean, properly adjusted, and securely mounted Correct answer.
  2. The mirrors are loose so they can be moved while driving
  3. The mirrors are adjusted to show only the sky
  4. One mirror is cracked but still shows an image

Explanation

Mirrors must be clean, securely mounted, and adjusted to give a clear view of the sides and rear of the vehicle. Cracks, poor adjustment, or loose mounts reduce visibility and are defects. Properly maintained mirrors are required equipment.

Question 21Basic Control of Your Vehicle

You are driving a fully loaded tractor-trailer on a dry, level road. Roughly how much longer is your total stopping distance compared with a passenger car traveling at the same speed?

  1. Roughly twice as long Correct answer.
  2. About the same as a passenger car
  3. Roughly half as long
  4. Roughly ten times as long

Explanation

A loaded combination vehicle needs considerably more distance to stop than a car at the same speed because of its much greater weight and the limited grip of its tires. The commonly taught figure is about twice the stopping distance of a passenger car under ideal dry conditions. Wet or icy pavement, worn brakes, and poor tire tread all stretch that gap further.

Question 22Basic Control of Your Vehicle

What is the safest way to bring a large combination vehicle to a stop on a dry, straight road?

  1. Pump the brake pedal rapidly several times
  2. Apply steady, controlled pressure and avoid locking the wheels Correct answer.
  3. Press the brake pedal hard and hold it until stopped
  4. Shift to neutral and coast until the vehicle rolls to a stop

Explanation

Smooth, progressive braking keeps the tires rolling and preserves steering control while the vehicle sheds speed. Slamming the pedal risks a wheel lockup and a skid, especially with an empty trailer. Coasting in neutral removes engine braking and leaves you without power if you need to accelerate out of trouble.

Question 23Basic Control of Your Vehicle

When you must stop quickly but the road surface is slippery, what should you do with the brake pedal?

  1. Tap it once and then hold it down hard
  2. Release it completely and use only the trailer brakes
  3. Apply it firmly but avoid locking the wheels Correct answer.
  4. Push it to the floor immediately

Explanation

On slick pavement the goal is maximum braking without skidding, so you brake firmly while keeping the wheels rolling enough to steer. Locked wheels slide and remove your steering control. If you feel a skid developing, ease off the brake and steer in the direction you want the front of the vehicle to go.

Question 24Basic Control of Your Vehicle

You are entering a curve posted for a lower speed than the one you are carrying. What is the recommended procedure?

  1. Slow down to a safe speed before you enter the curve Correct answer.
  2. Shift to a lower gear after you have passed the apex
  3. Brake hard while you are in the middle of the curve
  4. Accelerate through the curve to increase tire grip

Explanation

Speed should be reduced before the curve so the vehicle is already at a safe rate when the lateral load builds. Braking in a curve divides tire grip between slowing and turning, which raises rollover and skid risk. A gentle acceleration through the curve after slowing is acceptable, but the major speed reduction belongs before entry.

Question 25Basic Control of Your Vehicle

Which statement best describes the correct hand position for steering a commercial vehicle?

  1. Hands should be at the 9 and 3 o'clock or 8 and 4 o'clock positions Correct answer.
  2. One hand at 12 o'clock and the other on the shift lever
  3. Both hands should be at the top of the wheel
  4. Hands should be at the bottom of the wheel at 6 o'clock

Explanation

Keeping both hands on the sides of the wheel gives you the best control and lets you turn quickly in either direction. It also keeps your arms clear of an air bag if the vehicle has one. Placing a hand at the top or bottom reduces leverage and slows your reaction.

Question 26Basic Control of Your Vehicle

When backing a tractor-trailer, which technique gives you the most control?

  1. Back quickly so the trailer does not have time to drift
  2. Turn the steering wheel in the same direction you want the trailer to go
  3. Rely on the convex mirror alone for the whole maneuver
  4. Back slowly and use the mirrors, getting out to check if unsure Correct answer.

Explanation

Backing should be done slowly with frequent mirror checks so small corrections can be made before the trailer drifts. If you lose sight of your spotter or are unsure of clearance, stop and get out to look. Steering the wheel opposite the desired trailer direction is what actually turns the trailer.

Question 27Basic Control of Your Vehicle

What is the primary purpose of the retarder on a heavy vehicle?

  1. To increase engine power on steep climbs
  2. To replace the service brakes for all stops
  3. To help slow the vehicle on long downgrades without overheating the brakes Correct answer.
  4. To lock the rear wheels for a faster stop

Explanation

A retarder uses engine or driveline resistance to hold speed down on long descents, which keeps the service brakes cool and ready for an emergency. It supplements rather than replaces the brakes, and it does not stop the vehicle by itself. Retarders should be switched off on slippery surfaces because they can cause drive-wheel skids.

Question 28Basic Control of Your Vehicle

You are descending a long, steep grade with a heavy load. What is the correct braking approach?

  1. Shift to neutral and let gravity carry you down
  2. Ride the brakes lightly the whole way down
  3. Select a low gear before the descent and use the brakes only to control speed Correct answer.
  4. Use the trailer brakes alone to save the tractor brakes

Explanation

You should be in a low gear before the grade begins so engine braking helps hold your speed. The service brakes are then applied in short, firm applications to keep speed in check, not held on continuously. Continuous light braking builds heat and can lead to brake fade or a runaway.

Question 29Basic Control of Your Vehicle

While driving, your vehicle begins to skid on a wet road. What is the correct response?

  1. Turn the wheel toward the shoulder and hold it there
  2. Brake harder and steer sharply against the skid
  3. Accelerate to pull the vehicle straight
  4. Stop braking and steer in the direction you want the front of the vehicle to go Correct answer.

Explanation

When a skid starts, releasing the brake lets the tires regain grip and roll again. Steering in the direction you want the front of the vehicle to go helps the tires realign and brings the vehicle back under control. Hard braking or abrupt steering during a skid usually makes it worse.

Question 30Basic Control of Your Vehicle

What is a jackknife, and when is it most likely to occur?

  1. The tractor and trailer fold toward each other, often during hard braking on a slippery surface Correct answer.
  2. The trailer brakes apply before the tractor brakes on a dry road
  3. The trailer lifts its front wheels during hard acceleration
  4. The steering axle loses air pressure and the wheel locks

Explanation

A jackknife is the folding of the tractor and trailer at the coupling, and it most often follows locked drive wheels during hard braking on a low-traction surface. An empty or lightly loaded trailer with poor traction is especially vulnerable. Smooth braking and adequate following distance are the main defenses.

Question 31Basic Control of Your Vehicle

You must make a right turn at a corner and your trailer has a long rear overhang. What should you do?

  1. Accelerate through the turn to clear the corner quickly
  2. Turn from the right lane without any adjustment
  3. Start the turn early so the trailer cuts the corner
  4. Swing wide to the left before the turn and watch the right mirror for the trailer's rear wheels Correct answer.

Explanation

Long vehicles need extra room to the left before a right turn so the rear wheels do not track over the curb or a pedestrian. You should check the right mirror throughout the turn to watch the trailer's path. Turning too early or too fast causes off-tracking that clips the corner.

Question 32Basic Control of Your Vehicle

Why should you increase your following distance when driving a loaded combination vehicle?

  1. Because the engine runs hotter at highway speed
  2. Because the vehicle needs more room to stop and the driver's view ahead is limited Correct answer.
  3. Because the trailer brakes apply faster than the tractor brakes
  4. Because the vehicle accelerates more quickly than a car

Explanation

A heavier vehicle takes longer to stop, and the driver's forward view is partly blocked by the hood and the load, so more space is needed to see and react. The standard guidance is at least one second of following distance for each ten feet of vehicle length at speeds under 40 mph, plus an extra second above that. Extra space also gives others room to merge or brake.

Question 33Basic Control of Your Vehicle

When is it acceptable to use a vehicle's horn while driving in a built-up area?

  1. To greet another driver you recognize
  2. To express frustration in slow traffic
  3. To warn others of imminent danger Correct answer.
  4. To signal that you intend to pass a slower vehicle

Explanation

The horn is a warning device, so it should be used to alert others to a hazard they may not see. Using it for greetings, frustration, or as a passing signal is misuse and can startle or confuse other road users. Many jurisdictions restrict horn use in built-up areas to emergencies.

Question 34Basic Control of Your Vehicle

You are parked on a two-way street on a downhill grade with a curb on your right. Which wheel and parking-brake setup is correct?

  1. Front wheels turned toward the curb, parking brake set Correct answer.
  2. Front wheels turned toward the curb, transmission in neutral with the brake off
  3. Front wheels turned away from the curb, parking brake released
  4. Front wheels straight ahead, parking brake set

Explanation

Facing downhill with a curb, turn the front wheels toward the curb so the vehicle rolls into the curb if it moves. Set the parking brake and leave the transmission in a low gear or park. Turning the wheels away from the curb downhill lets the vehicle roll into traffic.

Question 35Basic Control of Your Vehicle

What is the correct way to check that your vehicle's brakes are working before a trip?

  1. Assume the brakes are fine if the vehicle moved under its own power
  2. Test the brakes at highway speed on the first open stretch
  3. Rely on the low-air warning buzzer only
  4. Build air pressure, then check for a firm pedal or proper air-brake response at low speed before pulling out Correct answer.

Explanation

A proper pre-trip check confirms that air pressure builds and holds and that the brakes respond firmly at low speed before you enter traffic. Testing at highway speed exposes you and others to a failure at the worst moment. Warning buzzers and the fact that the vehicle moves say nothing about braking performance.

Question 36Basic Control of Your Vehicle

When driving at night, what should you do if an oncoming vehicle's high beams glare into your eyes?

  1. Turn on your interior dome light for better vision
  2. Look toward the right edge of your lane and slow down Correct answer.
  3. Look directly at the headlights to judge the distance
  4. Flash your high beams back at the other driver

Explanation

Looking toward the right edge of your lane keeps your eyes away from the glare while you stay in your path. Slowing down gives you more time to react to anything hidden by the glare. Looking at the lights or retaliating with high beams reduces your own night vision.

Question 37Basic Control of Your Vehicle

You are driving in heavy fog and visibility is dropping. Which action is most appropriate?

  1. Reduce speed, use low beams, and increase your following distance Correct answer.
  2. Follow the tail lights of the vehicle ahead closely
  3. Stop in the travel lane and wait for the fog to clear
  4. Turn on your high beams to cut through the fog

Explanation

Fog scatters high-beam light back at the driver, so low beams give better visibility. Slowing down and adding following distance gives you time to react to hazards you cannot see far ahead. Tailgating another vehicle in fog removes your margin for error and invites a chain collision.

Question 38Basic Control of Your Vehicle

What does the term off-tracking describe when a long combination vehicle turns?

  1. The front wheels lift during hard acceleration
  2. The trailer pushes the tractor forward during braking
  3. The vehicle's speed increases as it enters a curve
  4. The rear wheels follow a path inside the path of the front wheels Correct answer.

Explanation

Off-tracking is the tendency of the rear wheels of a long vehicle to cut inside the path traced by the front wheels during a turn. The longer the wheelbase and trailer, the greater the amount of off-tracking. Drivers must allow for it by swinging wider and watching the mirrors so the trailer clears curbs and other vehicles.

Question 39Basic Control of Your Vehicle

A driver must stop on a narrow road at night with traffic approaching. Which combination best protects the stopped vehicle?

  1. Leave the vehicle in gear with the parking brake off
  2. Use four-way flashers, keep headlights on, and place reflective triangles behind the vehicle Correct answer.
  3. Stand behind the trailer to wave traffic around
  4. Turn off all lights so you are not a distraction

Explanation

When stopped on or near a road at night, you want the vehicle to be as visible as possible, so keep the lights on and use four-way flashers. Reflective triangles placed behind the vehicle warn approaching traffic of the hazard. Standing in the roadway yourself puts you at serious risk of being struck.

Question 40Basic Control of Your Vehicle

What is the safest way to handle a tire blowout on a front steer tire at highway speed?

  1. Accelerate to stabilize the vehicle, then shift down
  2. Brake hard immediately and steer for the shoulder
  3. Hold the wheel firmly, keep the vehicle straight, ease off the accelerator, and slow gradually Correct answer.
  4. Turn the wheel sharply away from the blowout side

Explanation

A front-tire blowout pulls the steering, so the first job is to grip the wheel and keep the vehicle tracking straight while you ease off the throttle. Hard braking or sharp steering can cause a loss of control or a rollover. Slow gradually, then move off the road once you have the vehicle under control.

Question 41Shifting Gears

In a manual-transmission CMV, what is the recommended sequence for shifting from a higher gear to a lower gear while descending a long grade?

  1. Skip directly to the lowest gear as soon as the descent begins so engine braking is strongest
  2. Coast in neutral to let the brakes cool, then select the gear that matches your final speed at the bottom
  3. Shift down one gear at a time after braking to the speed you want, using the engine and brakes together to hold that speed Correct answer.
  4. Hold the clutch pedal down through the whole descent and use the service brakes alone

Explanation

The standard technique is to slow to a safe speed before the grade and then select a lower gear, shifting one gear at a time so the engine and service brakes share the work. Shifting one gear at a time keeps engine rpm within a safe range and avoids overspeeding the engine or losing control.

Question 42Shifting Gears

You are driving a manual-transmission CMV and need to shift up while accelerating on a level road. Which clutch and throttle sequence is correct?

  1. Press the clutch, shift to the next higher gear, release the clutch fully, then accelerate
  2. Press the clutch, shift, release the clutch, press the accelerator, then press the clutch again
  3. Press the accelerator fully, then press the clutch and shift without releasing the throttle
  4. Release the accelerator, press the clutch, shift to the next gear, release the clutch smoothly, then apply throttle Correct answer.

Explanation

A smooth upshift means releasing the accelerator, disengaging the clutch, moving the shift lever to the next gear, re-engaging the clutch smoothly, and then applying throttle. Releasing the accelerator first reduces load on the transmission so the gear change is clean and the drivetrain is not shocked.

Question 43Shifting Gears

What is the main reason a heavy CMV should be shifted up progressively rather than lugging the engine in too high a gear?

  1. Lugging is acceptable as long as the engine does not stall
  2. Lugging in a high gear at low rpm strains the engine and drivetrain and reduces the power available to accelerate or climb Correct answer.
  3. Lugging causes the tachometer to read higher than actual engine speed
  4. Lugging shortens the life of the clutch release bearing only

Explanation

Operating in too high a gear at low rpm, called lugging, loads the engine and drivetrain heavily while producing little usable power. Progressive upshifting keeps engine speed in the efficient range and preserves acceleration and hill-climbing ability.

Question 44Shifting Gears

When shifting a manual-transmission CMV on a snowy or icy road, what adjustment should you make?

  1. Skip gears to reduce the number of shifts and release the clutch abruptly
  2. Use the same shift points and clutch release as on dry pavement
  3. Shift at higher engine rpm and release the clutch quickly to break traction loose
  4. Shift smoothly at lower rpm and release the clutch gradually to avoid wheel slip Correct answer.

Explanation

On slick surfaces, abrupt clutch engagement or high-rpm shifts can break traction at the drive wheels. Shifting smoothly at lower rpm and easing the clutch out reduces the chance of wheel spin and loss of control.

Question 45Shifting Gears

A CMV with an automatic transmission is descending a long mountain grade. How should the driver control speed?

  1. Shift to neutral and use the brakes lightly to avoid overheating
  2. Leave the selector in drive and rely on the service brakes to hold speed the entire way down
  3. Accelerate to build momentum so the descent is finished sooner
  4. Select a lower gear range so the transmission and engine help hold speed, and use the brakes to control any gain Correct answer.

Explanation

Automatic transmissions in heavy vehicles usually allow the driver to select a lower range that provides engine braking on a descent. Combining that lower range with controlled service-brake use keeps brakes from overheating.

Question 46Shifting Gears

What does a splitter (range) shift on a heavy-duty manual transmission allow the driver to do?

  1. Change the final drive ratio while the vehicle is moving
  2. Disengage the clutch automatically during each shift
  3. Lock the transmission in one gear to prevent downshifting on grades
  4. Select between two gear ratios within the same main gear position to fine-tune engine speed Correct answer.

Explanation

A splitter or range selector lets the driver choose between two ratios within a main gear position, which gives finer control of engine rpm for load and grade conditions. It does not change the final drive ratio or operate the clutch automatically.

Question 47Shifting Gears

While climbing a steep grade with a heavy load, your CMV begins to lose speed and the engine rpm drops toward the bottom of its operating range. What is the best action?

  1. Upshift to reduce engine rpm and let the load carry the vehicle up
  2. Keep the current gear and press the accelerator harder until the engine recovers
  3. Downshift to a lower gear before the engine lugs, then continue the climb Correct answer.
  4. Stop on the grade and restart in a higher gear

Explanation

When rpm falls toward the bottom of the operating range on a climb, the engine is beginning to lug and power is dropping. Downshifting before that point restores rpm and keeps the vehicle moving under control.

Question 48Shifting Gears

Why is it important to avoid coasting with the clutch disengaged or the transmission in neutral in a CMV?

  1. It causes the tachometer to fail
  2. It prevents the transmission from warming up
  3. It increases fuel economy but is otherwise harmless
  4. It removes engine braking and reduces your ability to control speed and accelerate out of trouble Correct answer.

Explanation

Coasting in neutral or with the clutch disengaged eliminates engine braking and leaves the driver unable to accelerate immediately if needed. It also reduces control on downgrades and is unsafe and often prohibited.

Question 49Shifting Gears

You are driving a manual-transmission CMV and need to downshift while slowing for a turn. What is the recommended technique?

  1. Brake to the safe speed first, then shift to the gear that matches that speed before entering the turn Correct answer.
  2. Shift to neutral during the turn and select a gear once straight
  3. Hold the clutch in through the turn and select a gear after exiting
  4. Downshift before braking so the engine slows the vehicle through the turn

Explanation

The safe sequence is to slow to the proper speed with the brakes, then select the gear that matches that speed before entering the turn. This keeps the drivetrain engaged and power available through the curve.

Question 50Shifting Gears

A driver repeatedly slips the clutch for several seconds while starting a loaded CMV on a hill. What is the most likely result?

  1. The clutch will overheat and wear rapidly, reducing its grip and service life Correct answer.
  2. The transmission will shift more smoothly on later shifts
  3. The engine will produce more torque at low rpm
  4. The clutch will last longer because it is being used gently

Explanation

Slipping the clutch for extended periods generates heat and wears the friction surfaces, which shortens clutch life and can reduce its ability to transmit torque. A hill start should use the clutch briefly and smoothly with the parking brake or proper technique to prevent rollback.