CDL General Knowledge Test flashcards

The condition of the fifth wheel assembly's components, including the skid plate, ensuring they are free from damage like cracks or deep gouges that could lead to coupling failure.

• Critical for safe tractor-trailer connection.
• Cracks or deep gouges indicate structural failure.
• Requires immediate repair or replacement if damaged.

Memory trick: Cracks and gouges mean the truck goes off the road, no excuses.

When backing a combination vehicle, to turn the trailer in a desired direction, the tractor's steering wheel must initially be turned in the opposite direction.

• Counter-intuitive steering.
• Small, quick steering corrections.
• Constant mirror use is essential.

Memory trick: Turn the wheel the opposite way, then follow the trailer's sway.

Jackknifing occurs when the tractor and trailer fold together at a sharp angle. Keeping the vehicle straight while backing is the primary method to prevent this dangerous condition.

• Occurs if trailer swings too far.
• Can cause severe damage and loss of control.
• Straight-line backing minimizes the risk.

Memory trick: Straight back, no crack; angled back, you'll feel the smack.

The maximum allowable pressure drop in an air brake system over a specific time, indicating system integrity.

• Combination vehicles have a higher allowable drop due to more connections.
• Insufficient pressure drop indicates a leak.
• Checked with the service brake applied.

Memory trick: Four pounds for all the lines, keeps the brakes in fine designs.

Bobtailing (driving a tractor without a trailer) reduces weight over the drive wheels, leading to significantly decreased traction and increased risk of jackknifing, especially on slippery roads.

• Less weight on drive axles.
• Higher risk of wheel spin and lock-up.
• Requires careful driving on slippery surfaces.

Memory trick: Light in the rear, spin in the gear.

Procedure to verify that the trailer's service brakes are functioning correctly using the hand valve.

• Performed during pre-trip inspection.
• Tractor brakes set, trailer brakes released.
• Involves a gentle tug while applying hand valve.

Memory trick: Tractor set, trailer free, hand valve tests for you and me.

Disconnecting the emergency air line should apply the trailer's spring brakes. Failure to do so indicates a critical fault in the emergency braking system.

• Red glad hand = emergency.
• Disconnecting applies spring brakes.
• Failure = unsafe condition.

Memory trick: Red line off, brakes don't bite, something's wrong, not right.

Techniques to avoid or recover from a jackknife during braking, especially on slippery surfaces.

• Avoid locking drive or trailer wheels.
• Release brakes to regain steering.
• Steer into the skid (if safe).

Memory trick: Release the brake, then steer, banish all your jackknife fear.

A valve on the tractor that automatically seals the emergency (red) air line when it is disconnected from a trailer, preventing air loss from the tractor's air tanks.

• Seals the emergency line when uncoupled.
• Prevents air loss from tractor system.
• A leak indicates a faulty valve on the tractor.

Memory trick: Red leak when alone, the tractor's valve has flown.

The application of grease to the fifth wheel plate to reduce friction between the tractor and trailer, ensuring smooth turning and preventing excessive wear.

• Reduces friction
• Prevents premature wear of components
• Aids in smooth steering and maneuvering

Memory trick: Grease is the peace for the fifth wheel's squeeze.

Before releasing the fifth wheel jaws during uncoupling, crank the landing gear a few extra turns to lift the trailer slightly off the fifth wheel, relieving kingpin pressure.

• Done after landing gear touches ground.
• Relieves pressure on kingpin.
• Facilitates fifth wheel release.
• Prevents damage to coupling components.

Memory trick: Landing gear down, then a little lift to ease the shift.

The 'tug test' is a vital step after backing under a trailer to physically verify that the fifth wheel locking jaws have securely engaged the kingpin before raising the landing gear.

• Prevents trailer separation.
• Should be done before raising landing gear.
• Especially critical on uneven or sloped ground.

Memory trick: Tug before you lift, or your trailer might drift.

Regularly checking glad hand seals for damage is crucial to maintain air brake system integrity and prevent air leaks.

• Seals prevent air loss.
• Damage can lead to brake failure.
• Part of pre-trip inspection.

Memory trick: Air-tight connections keep the brakes right.

The fifth wheel locking jaws must be fully closed and secured around the kingpin for a safe connection between the tractor and trailer.

• Prevents trailer detachment.
• Must be visually inspected after coupling.
• An open or partially closed jaw indicates an unsafe condition.

Memory trick: Open jaws mean a re-do, no half-measures.

Verifying that the fifth wheel locking jaws have fully closed around the trailer's kingpin after backing the tractor under the trailer.

• Prevents trailer separation.
• Done visually and by tugging the tractor.
• Crucial safety step in coupling.

Memory trick: Back, Check, Connect, Raise, Secure, Test.

Procedure to verify the functionality of a combination vehicle's trailer emergency brakes.

• Uses the trailer air supply valve (red knob).
• Verifies spring brake application.
• Confirmed by a gentle tug test.

Memory trick: Red knob out, no roll about.

A mechanism that locks the fifth wheel operating handle in the closed position, preventing accidental release of the kingpin and trailer detachment.

• Prevents accidental uncoupling.
• Must be engaged after coupling.
• A critical safety feature for combination vehicles.

Memory trick: No pin, no win, just the trailer spinning.

To prevent off-tracking, a driver must swing wide in the opposite direction of the turn to allow the trailer sufficient room to follow the tractor.

• Trailer cuts corners.
• Swing wide opposite turn.
• Creates space for trailer.

Memory trick: To avoid a cut, take a wider strut.

The maximum allowable air pressure drop in a combination vehicle's air brake system during a service brake application test, indicating system integrity.

• Engine off, air tanks full.
• Service brake applied and held.
• Maximum allowable drop: 4 psi in one minute.

Memory trick: Pressure drops, but not too fast, or your brake's past its last.

When trailer wheels lock before tractor wheels during braking, often due to brake adjustment or loading issues.

• Can lead to trailer jackknife.
• Often caused by improperly adjusted brakes.
• More common with empty or light trailers.

Memory trick: Locking early means adjustment's not pearly.

Coupling on an uneven surface increases the risk of improper kingpin engagement, leading to an unsafe and potentially detached trailer.

• Causes misalignment.
• Kingpin may not lock.
• Trailer detachment risk.

Memory trick: Uneven ground, unsafe sound; keep it flat, or risk a breakdown.

Air leaks at glad hands are typically caused by worn or damaged rubber seals (gaskets) and are best repaired by replacing these seals.

• Essential for maintaining air pressure.
• Prevents brake system failure.
• Seals are inexpensive and easy to replace.

Memory trick: A leaky glad hand needs a new gasket, not just a twist.

Daily draining of air tanks removes accumulated water and oil, protecting the air brake system from damage and ensuring proper function.

• Removes water and oil.
• Prevents corrosion.
• Prevents freezing.

Memory trick: Drain the tank, keep it clean, prevent the brake system from being mean.

Checking the condition and connection of the electrical cable between the tractor and trailer to ensure proper operation of trailer lights and electrical systems.

• Must be free of cuts, chafing, or exposed wires.
• Securely connected at both ends.
• Not dragging on the ground.

Memory trick: Lights on, wires tight, everything's right.

Deterioration of the kingpin's material, specifically a reduction in its diameter, due to friction and stress during coupling and driving.

• Compromises coupling security.
• Increases risk of trailer separation.
• Must be within specified tolerances.

Memory trick: King's pin must be strong, not thin.

The rubber seals within glad hands are crucial for maintaining an airtight connection between the tractor and trailer air brake lines.

• Seals prevent air leaks.
• Damaged seals lead to brake system failure.
• Inspect seals during pre-trip.

Memory trick: Air leaks kill brakes, seals are key.

An excessive brake pushrod stroke indicates the brake is out of adjustment, requiring investigation and repair of the slack adjuster or other brake components.

• Beyond maximum allowed limit.
• Indicates maladjustment.
• Requires immediate repair.

Memory trick: Long stroke, system broke; check the slack, get on track.

Seals at the electrical cable connections are vital for protecting contacts from environmental damage, ensuring reliable transmission of power for lights and signals.

• Prevents moisture and corrosion.
• Maintains electrical continuity.
• Essential for safety lights and signals.

Memory trick: A tight seal keeps the lights bright and clear.

Air lines connecting the tractor and trailer must be free from damage that compromises their ability to hold air pressure, such as bulges, cracks, or severe chafing.

• Ensures brake system functionality.
• Prevents air leaks.
• Critical for safe operation of combination vehicles.

Memory trick: Look for bulges, breaks, or bends, to keep your air flowing, my friend.

A procedure performed after coupling to verify that the fifth wheel locking jaws are securely engaged with the kingpin.

• Trailer parking brakes applied, tractor parking brakes released.
• Tractor gently pulled forward.
• Confirms secure connection, prevents separation.

Memory trick: Trailer holds, tractor tugs, connection bugs.

The condition of the rubber seals within glad hands is crucial for preventing air leaks in the air brake lines of combination vehicles.

• Seals must be soft and pliable.
• Must be free from cracks, cuts, or hardening.
• Damaged seals cause air leaks and brake system failure.

Memory trick: Soft seals keep the air flowing, cracked ones will leave you blowing.

During uncoupling, after the landing gear contacts the ground, the trailer must be slightly raised to transfer its weight off the tractor's fifth wheel, facilitating a clean separation.

• Prevents damage to fifth wheel and kingpin.
• Ensures smooth uncoupling.
• A crucial step before releasing the fifth wheel jaws.

Memory trick: Lower, Lift, Disconnect, Release, Drive.

To recover from a jackknife while backing, stop immediately and pull forward to straighten the vehicle before attempting to back again.

• Occurs when tractor and trailer form a sharp angle.
• Immediate stop is crucial.
• Pulling forward corrects the angle.
• Avoid sharp steering or trailer brakes.

Memory trick: When things go wrong, go straight and try again.

Verifying that the trailer's parking brakes are set and holding the trailer stationary before moving the tractor away.

• Prevents trailer runaway.
• Usually automatic when air lines are disconnected.
• Must be visually confirmed.

Memory trick: Park, Lower, Disconnect, Check, Pull, Clear.

A rhythmic forward and backward jerking motion felt in a combination vehicle, typically during changes in speed, caused by excessive play in the coupling components.

• Caused by worn kingpin or fifth wheel.
• Indicates excessive movement between tractor and trailer.
• Requires immediate inspection and repair.

Memory trick: Chucking means your connection's sucking.

Components within the fifth wheel that secure the trailer's kingpin, preventing separation.

• Critical for safe coupling.
• Must be fully closed around the kingpin.
• Wear indicates a severe safety hazard.

Memory trick: Jaws that are weak, a trailer might leak (away).

The pressure range at which the air compressor stops pumping air into the system, typically between 100-125 psi, to prevent over-pressurization.

• Regulates maximum system air pressure.
• Protects system components from damage.
• Must be checked during pre-trip inspection.

Memory trick: One hundred to one twenty-five, keeps your air system alive.

A leaking service glad hand indicates a critical air brake system defect that must be repaired before driving to ensure trailer braking capability.

• Affects trailer service brakes.
• Severe safety hazard.
• Repair required immediately.

Memory trick: Leaking blue means no go, fix it now, don't be slow.

Rearward amplification is a dynamic instability where the yaw (swaying) motion of the tractor is amplified toward the rear of a combination vehicle, making the tail swing out significantly more.

• More pronounced with short tractors and long trailers.
• Increased risk with multiple trailers.
• Can lead to rollovers or striking objects.

Memory trick: Short tractor, long trailer, big swing, big danger.

The technique of steering a combination vehicle in reverse, where the steering wheel is initially turned opposite to the desired direction of the trailer's movement.

• Steer opposite to trailer's desired direction.
• Small corrections are key.
• Use mirrors frequently.

Memory trick: To go right, steer left; to go left, steer right.

The red glad hand line that supplies air to the trailer's air tanks and releases its spring brakes.

• Also known as the supply line.
• Loss of pressure applies trailer brakes.
• Connects to the trailer's air reservoir.

Memory trick: Red for release, blue for the squeeze.

Ensuring the fifth wheel locking jaws are fully closed around the kingpin shank is the most critical check for a secure tractor-trailer connection.

• Prevents trailer separation.
• Check visually and with a tug test.
• Release handle should be in locked position.

Memory trick: Jaws must bite, or the trailer takes flight.

When backing a combination vehicle, to turn the trailer, steer the tractor in the opposite direction of the desired trailer turn, and primarily watch the mirror on the side opposite the direction of the turn to monitor trailer movement.

• Steer tractor opposite to desired trailer turn.
• Use mirrors constantly.
• Primary focus is the mirror on the side opposite the turn for guiding the trailer's rear.

Memory trick: Opposite steer, opposite mirror, that's how you get your trailer clear.

A technique for descending long, steep grades in combination vehicles that involves using a low gear and engine braking, supplemented by intermittent, firm applications of the service brakes.

• Prevents brake fade by reducing heat.
• Maintains vehicle control.
• Requires selecting the correct gear before descent.

Memory trick: Gear low, brakes cool, control the roll.

The phenomenon where the rear wheels of a combination vehicle's trailer follow a shorter path than the tractor's wheels during a turn.

• Occurs in all combination vehicles.
• Increases with longer trailers and sharper turns.
• Requires drivers to allow extra space during turns.

Memory trick: Always remember the 'tail' always cuts the corner.

To recover from a trailer jackknife, release the service brakes to allow the trailer wheels to roll freely, then steer gently to straighten the vehicle.

• Caused by trailer wheels locking up.
• Release brakes to regain traction.
• Gentle steering is key to control.

Memory trick: Release and ease, then steer to please.

Techniques used to regain control of a combination vehicle when the trailer begins to fishtail or skid.

• Involves steering into the skid.
• Requires easing off the accelerator.
• Avoids harsh braking or hand valve use.

Memory trick: Steer where you want to go, ease the gas, avoid the tow.

Automatic slack adjusters maintain brake adjustment automatically. Frequent manual adjustment signals a system defect, not routine maintenance.

• Self-adjusting mechanism.
• Manual adjustment is rare.
• Frequent adjustment = problem.

Memory trick: Auto-adjusters keep brakes tight; if not, something's not right.

When the trailer's wheels skid during braking due to excessive braking force for its actual weight, often occurring when the trailer is empty or lightly loaded.

• Common with empty or light trailers.
• Can lead to jackknifing.
• Requires careful brake application and adjustment.

Memory trick: Weight matters, too little makes the trailer slide.

The tug test confirms the secure mechanical connection between the tractor's fifth wheel and the trailer's kingpin.

• Performed after coupling.
• Verifies fifth wheel jaws are locked.
• Prevents accidental uncoupling.
• Involves gently pulling forward.

Memory trick: Lock and Tug for a secure hug.

Heavy loads in a combination vehicle trailer should be placed directly over or slightly forward of the trailer axles to ensure proper weight distribution, stability, and safe handling.

• Prevents trailer sway.
• Ensures adequate drive axle traction.
• Avoids overloading steering axle.
• Critical for stability and control.

Memory trick: Heavy loads, axle loads, keep it in the zones.

A properly coupled kingpin should have no discernible play within the fifth wheel jaws.

• Any play indicates wear or improper connection.
• Play leads to chucking and damage.
• Critical safety check.
• Requires immediate attention if found.

Memory trick: Tight as a drum, safe as a ride.

The allowable movement of a slack adjuster when pulled by hand, indicating proper brake adjustment.

• Crucial for effective braking.
• More than 1 inch means maladjustment.
• Affects all air-braked vehicles.

Memory trick: One inch of play is the most for the day.

Fasteners securing the fifth wheel skid plate to the tractor frame are critical for maintaining a stable connection and preventing movement of the fifth wheel assembly.

• Ensure secure mounting of the fifth wheel.
• Prevent unstable handling.
• Missing or worn fasteners are a critical safety defect.

Memory trick: Tight fasteners mean a steady ride; loose ones mean trouble inside.

The visual check to ensure the fifth wheel's locking jaws are properly closed around the trailer's kingpin shank, confirming a secure mechanical connection.

• Performed immediately after backing under the trailer.
• Precedes the tug test and raising landing gear.
• Critical for preventing accidental uncoupling.

Memory trick: Back, Look, Tug, Connect, Lift, Inspect.

A properly coupled fifth wheel ensures the kingpin is fully engaged in the locking jaws with the safety latch secured, preventing trailer separation.

• Kingpin fully seated.
• Locking jaws closed.
• Safety latch engaged.

Memory trick: Kingpin locked, safety latched, trailer attached.

The amount of movement in the steering wheel before the steering mechanism begins to turn the wheels.

• Excessive play indicates worn components.
• Maximum allowable is 10 degrees or ~2 inches on a 20-inch wheel.
• Checked during pre-trip inspection.

Memory trick: Ten degrees or three inches, no more for a good drive.

A procedure to physically verify the secure connection of the kingpin to the fifth wheel by gently pulling the tractor against the trailer's set brakes.

• Performed after locking jaws engage.
• Before raising landing gear.
• Confirms a safe coupling.

Memory trick: Lock, look, then tug, before you raise the landing rug.

A condition where a combination vehicle's trailer brakes lock up prematurely or with minimal pedal pressure, often due to improper adjustment or brake aggressiveness.

• Indicates brakes are too tight or over-adjusted.
• Can lead to trailer skids and loss of control.
• Requires immediate inspection and adjustment.

Memory trick: Locking up lightly means the brakes are too tightly.

Chucking or surging in a combination vehicle is usually caused by excessive play or wear in the kingpin and/or fifth wheel connection, leading to independent movement between tractor and trailer.

• Feels like a push/pull motion.
• Occurs during acceleration/deceleration.
• Indicates loose connection.
• Inspect kingpin and fifth wheel.

Memory trick: Loose link, rough ride.