CDL Combination Vehicles Test flashcards

The air line, typically blue, that carries air from the tractor's foot valve or hand valve to the trailer's service brake chambers for normal braking.

• Connects to trailer service brakes.
• Controls normal braking on the trailer.
• A leak prevents service brake application.

Memory trick: Blue for service, red for emergency, keep them tight to stay free.

Proper cargo securement prevents movement during transit, ensuring vehicle stability, preventing damage to cargo, and protecting other road users.

• Cargo must be contained, immobilized, or secured.
• Use appropriate tie-downs, dunnage, and bracing.
• Check securement before, during, and after trips.
• Federal regulations (FMCSA) dictate securement standards.

Memory trick: Loose cargo makes for a loose driver.

A check valve in a dual air brake system is a one-way valve that isolates the primary and secondary air tanks, ensuring that a leak in one system does not deplete the air pressure from the other system.

• One-way air flow.
• Maintains system redundancy.
• Crucial for safety in case of air leak.

Memory trick: A check valve 'Checks' air flow, ensuring 'Safety' in a dual system.

A safety device in the air brake system, usually located on the first air tank, that automatically releases air pressure if it exceeds a predetermined safe limit (typically 150 psi) to prevent system damage.

• Protects air tanks and components from over-pressurization.
• Activates around 150 psi.
• Essential safety feature.

Memory trick: Safety Valve Saves System.

When another vehicle merges too closely in front of a combination vehicle, gently reduce speed to re-establish a safe following distance.

• Combination vehicles need longer stopping distances.
• Aggressive reactions are unsafe.
• Prioritize creating space.

Memory trick: Close Car, Calmly Create Clearance.

Safely navigating curves in a combination vehicle requires reducing speed before entering the curve and maintaining a controlled speed throughout.

• Always heed advisory speed signs for curves.
• Brake before the curve, not in it.
• Accelerate gently out of the curve.

Memory trick: Curve's embrace, speed's slow dance, then a gentle pace.

When the low air pressure warning light and buzzer activate (typically below 60 psi), the driver must immediately stop driving and not move the vehicle until pressure returns to a safe operating range.

• Indicates insufficient braking pressure.
• Requires immediate stop.
• Do not move until pressure is safe.

Memory trick: Low air, light and buzzer, means stop, no fuss, no flutter.

Storage points on a tractor or trailer for glad hands when not connected, protecting them from damage and preventing air loss.

• Protects glad hands.
• Prevents air system contamination.
• Maintains air pressure in tractor lines.

Memory trick: Dummy for storage, not for air leakage shortage.

If the fifth wheel release arm is not fully seated in its locked position after coupling, it indicates an insecure connection that requires immediate uncoupling and meticulous re-coupling until the arm is definitively locked.

• Release arm position indicates jaw lock status.
• Not fully locked = potential trailer separation.
• Never operate with an unsecured coupling.
• Recoupling is the only safe solution.

Memory trick: Arm Not Locked? Uncouple, Recouple, Re-rock!

A bent or cracked kingpin is a critical structural defect that makes a trailer immediately unsafe to operate due to the high risk of catastrophic failure and separation.

• Compromises coupling integrity.
• Leads to immediate 'out-of-service' condition.
• Must be repaired or replaced before use.

Memory trick: Bent or cracked? Trailer's been attacked!

The space between the tractor's fifth wheel and the trailer's upper plate when coupled. No gap is acceptable.

• Indicates proper coupling or wear.
• Should be flush when locked.
• A gap is a critical safety defect.

Memory trick: No space, safe place.

The correct orientation of the fifth wheel plate (tilted down towards the rear) and the state of its jaws (open) prior to backing under a trailer for coupling.

• Jaws open and ready.
• Plate tilted down at rear.
• Helps kingpin slide in.
• Prevents high coupling.

Memory trick: Open jaws, tilt down, and couple with a frown!

Backing a tractor at an angle during coupling significantly increases the risk of severe damage to the kingpin, fifth wheel, or trailer apron, compromising the safety and integrity of the coupling.

• Kingpin must enter jaws squarely.
• Angular impact can bend/break components.
• Leads to unsafe coupling or equipment failure.
• Always aim for straight alignment.

Memory trick: Angle's a Blunder, Damage is Thunder.

Proper management of the tractor-trailer electrical cable, including correct slack and secure fastening, is essential to prevent physical damage and ensure continuous electrical connection during operation.

• Too little slack: cable can snap during turns.
• Too much slack/dragging: cable can chafe, snag, or be crushed.
• Damage to cable can disable lights, ABS, or other systems.

Memory trick: Slack for Turns, High for Safe Runs.

The condition of the locking mechanism within the fifth wheel, which should be closed and secure around the kingpin when coupled, or open via the release arm when uncoupled.

• Jaws open = uncoupled or faulty.
• Jaws closed = coupled or ready for coupling (with release arm pushed in).
• Release arm controls jaw state.

Memory trick: Jaws open without release means a dangerous surprise.

Before disconnecting air lines during uncoupling, the trailer's parking brakes must be applied to secure the trailer.

• Prevents trailer runaway.
• Ensures safety during air line disconnection.
• Critical step after landing gear is down.

Memory trick: Secure trailer first, then disconnect.

The process of visually and physically confirming that the trailer's kingpin is securely engaged and locked within the fifth wheel jaws of the tractor.

• Crucial safety step during coupling.
• Prevents trailer separation.
• Involves a visual check of the locking jaws.

Memory trick: Lock the kingpin, verify with a tug, then connect everything up.

A test performed during coupling by gently pulling the tractor forward against the trailer's set brakes to ensure the kingpin is securely locked in the fifth wheel jaws.

• Verifies proper kingpin engagement.
• Done after air/electrical connections.
• Prevents trailer separation while driving.

Memory trick: Tug to confirm the connection is snug.

The process of using the trailer's landing gear to set its height appropriately for coupling or uncoupling.

• Crucial for proper kingpin alignment.
• Prevents damage during coupling.
• Adjusted via landing gear crank.

Memory trick: Too high, go low. Too low, go high.

Before backing under a trailer, the fifth wheel must be properly lubricated and tilted down to accept the kingpin, ensuring a safe and smooth connection.

• Lubrication reduces friction and wear.
• Tilt allows kingpin to slide into jaws.
• Incorrect preparation can cause damage or improper coupling.

Memory trick: Lube and Tilt, then Back and Connect.

A procedure performed during coupling to verify that the tractor and trailer are securely connected by the fifth wheel and kingpin.

• Done immediately after kingpin lock.
• Involves gently tugging the tractor forward.
• Ensures jaws are properly closed.

Memory trick: Lock it, then tug it to confirm!

The step in uncoupling where the air lines (service and emergency) and the electrical cable are physically separated from the trailer's connections.

• Performed after landing gear is down.
• Prevents damage to lines/cables.
• Ensures full separation capability.

Memory trick: Landing Gear Down, Then Lines Out!

The air line (connected via a red glad hand) that supplies air pressure from the tractor to the trailer's air tanks, releasing the trailer's spring-actuated emergency brakes.

• Red glad hand connection.
• Charges trailer air tanks.
• Releases trailer emergency brakes.
• If disconnected, trailer emergency brakes apply.

Memory trick: Red is for Release, Blue is for Brake!

Any audible air leak at glad hand connections requires immediate attention. The correct procedure is to disconnect, inspect seals, clean, and then reconnect for a proper, airtight fit.

• Air leaks compromise brake system pressure.
• Gaskets must be clean and undamaged.
• Proper reconnection ensures a tight seal.

Memory trick: Hear a Hiss? Re-Connect, Don't Miss.

Any crack in the fifth wheel apron plate, a critical structural component, is a serious defect that renders a combination vehicle unsafe for operation and requires immediate repair.

• Apron plate supports trailer weight on fifth wheel.
• Cracks compromise structural integrity.
• Vehicle must be taken out of service for repair.

Memory trick: Cracks mean Stop, don't Risk a Drop.

Receptacles on the tractor where glad hands are stored when disconnected from the trailer, protecting them from contamination.

• Prevents dirt and moisture ingress.
• Protects air brake system integrity.
• Standard safety and maintenance practice.

Memory trick: Dummy couplers keep the air lines clean and ready.

The practice of properly routing and securing the trailer's electrical cable to prevent chafing, damage, and ensure continuous electrical function.

• Prevents cable damage.
• Ensures reliable lights and ABS.
• Part of pre-trip and coupling checks.

Memory trick: Secure the wire, prevent the fire (or failure).

The angle of the fifth wheel plate, typically tilted down towards the rear, to facilitate the entry of the trailer's kingpin during coupling.

• Aids smooth coupling.
• Prevents damage to components.
• Requires jaws to be open.

Memory trick: Tilt it down, jaws apart, ready for the start.

The minimum vertical and horizontal distance maintained between the trailer's landing gear and the tractor's frame/components, particularly during turns.

• Prevents component damage.
• Ensures safe maneuvering.
• Typically 6 inches minimum clearance.

Memory trick: Six inches of space keeps parts in their place.

A condition where the fifth wheel release arm is not fully returned to its locked position after coupling, indicating the kingpin may not be securely held by the jaws.

• High risk of trailer separation.
• Requires immediate correction before driving.
• Often indicates incomplete kingpin engagement.

Memory trick: Lock That Arm, Or Harm Will Come.

Before coupling, the trailer's landing gear must be fully extended and stable to prevent the trailer from tipping or collapsing in case of a kingpin or fifth wheel coupling failure.

• Provides structural support for the trailer.
• Prevents trailer from falling if coupling fails.
• Ensures stability during the coupling sequence.

Memory trick: Gear Down, Ground Firm, Safety's Confirmed.

The process of lowering and stabilizing the trailer's landing gear to support its weight when uncoupled from the tractor.

• Critical for trailer stability.
• Prevents trailer from dropping.
• Done before moving the tractor away.

Memory trick: Air and Electric off, then Legs down, then Tractor away.

Before backing under a trailer, the fifth wheel should be tilted slightly down towards the rear and the jaws must be open to facilitate safe and proper coupling.

• Aids kingpin entry.
• Prevents damage to components.
• Ensures reliable coupling.

Memory trick: Down and open, ready for the kingpin token.

During a pull test, releasing the trailer's parking brake allows the driver to verify that the fifth wheel jaws are securely locked around the kingpin by attempting to gently pull the stationary trailer with the tractor.

• Tractor brakes set, trailer brakes released.
• Gently tug forward with tractor.
• If trailer moves, connection is NOT secure.
• Tests mechanical coupling, not brake function.

Memory trick: Release for Roll, Lock for Goal.

The maximum allowable reduction in the kingpin's diameter due to wear before it must be replaced or repaired to ensure safe coupling.

• Max wear: 1/8 inch from original diameter.
• Critical for coupling integrity.
• Checked during pre-trip inspections.
• Exceeding limit is a safety violation.

Memory trick: One-Eighth Inch, No More, or it's out the door!

Specific criteria for inspecting the kingpin for signs of wear, damage, or deformation that could compromise its ability to securely couple with the fifth wheel.

• Critical for safe coupling.
• Deep gouges/cracks are dangerous.
• Must meet industry standards for integrity.

Memory trick: A deep gouge on the kingpin is a dangerous sign.

A condition where the kingpin is partially engaged in the fifth wheel jaws, but the jaws are not fully closed and locked, often indicated by an unseated release arm.

• Extremely dangerous, can lead to trailer separation.
• Requires immediate correction before driving.
• Often detected by visual inspection of release arm and kingpin.

Memory trick: Visible kingpin, unseated arm, means alarm!

Coupling on uneven ground creates significant risks, primarily the unpredictable movement or rolling of the trailer, which can cause serious accidents.

• Increases risk of trailer runaway.
• Makes alignment difficult.
• Can damage equipment.

Memory trick: Level ground for a secure sound.

During uncoupling, the landing gear must be fully cranked down to firmly support the trailer's weight before disconnecting air/electrical lines and moving the tractor.

• Ensures trailer stability.
• Prevents trailer nose drop.
• Critical safety step.

Memory trick: Gear down, then lines out, no trailer doubt.

Ensuring the fifth wheel plate is fully in contact with the trailer's apron after the kingpin is locked, indicating a secure and safe coupling.

• Prevents high coupling.
• Confirms kingpin is seated correctly.
• Essential safety check before moving.

Memory trick: Always Double Check Connections Before You Roll.

During uncoupling, after the landing gear is down, chocking the trailer wheels is an essential safety measure to prevent unintentional trailer movement once the tractor is separated.

• Prevents rolling on slopes or uneven ground.
• Backup for trailer brake failure.
• Performed before releasing fifth wheel.

Memory trick: Gear, Disconnect, Chock, Release.

A safety procedure during coupling where the tractor is gently pulled forward against the trailer's set brakes to confirm the kingpin is securely locked in the fifth wheel.

• Confirms mechanical connection.
• Performed after kingpin engagement.
• Crucial safety step.

Memory trick: Pull to prove the lock is true.

After securing the trailer on its landing gear and disconnecting utilities, the fifth wheel release handle must be pulled to disengage the kingpin, allowing the tractor to separate.

• Release handle opens fifth wheel jaws.
• Must be done before moving tractor.
• Ensures kingpin is free.

Memory trick: Lower, Disconnect, Release, Drive.

A bent kingpin is a critical structural defect that compromises the safety and integrity of the tractor-trailer coupling, rendering the vehicle unsafe for operation until professionally repaired or replaced.

• Kingpin is the primary coupling point.
• Bending indicates severe stress or damage.
• Compromises secure lock with fifth wheel jaws.
• Immediate out-of-service condition.

Memory trick: Bent Kingpin = Broken Link, Don't Risk, Don't Think.

The act of detaching the glad hands (air lines) and the electrical cable that connect the tractor to the trailer, a crucial step in the uncoupling process.

• Prevents damage to lines.
• Must be done before pulling away.
• Ensures trailer brakes remain applied (if emergency line disconnected first).

Memory trick: Gear Down, Lock Off, Lines Out, Then Pull.

The angle of the fifth wheel plate, which should be tilted slightly down towards the rear of the tractor to facilitate proper kingpin entry during coupling.

• Aids kingpin entry into throat.
• Ensures proper seating for locking.
• Prevents 'high coupling' or missed connections.

Memory trick: Tilt it down, so the kingpin slides all around!

Corrosion on glad hands can lead to improper sealing of air lines, resulting in air leaks and reduced airflow, compromising trailer brake system effectiveness.

• Affects air line integrity.
• Causes air leaks.
• Impairs brake system functionality.

Memory trick: Corroded glad hand, air escapes from your hand.

When driving a combination vehicle with Anti-lock Braking Systems (ABS), the proper technique for emergency braking is to apply firm, steady pressure to the foot brake pedal.

• ABS prevents wheel lock-up automatically.
• Do not pump the brakes with ABS.
• Allows the driver to maintain steering control.
• Works on all axles with ABS.

Memory trick: ABS is your steady friend, press the pedal, to the very end.

Safety chains or cables are essential connections between a converter dolly and the lead trailer to prevent separation in the event of a pintle hook or drawbar failure, ensuring the dolly remains attached.

• Required for all converter dollies.
• Must be securely attached and crossed.
• Prevents runaway dolly/trailer.
• Checked during coupling and pre-trip inspection.

Memory trick: Dolly's ready, but don't just dash, first secure the chains, a safety flash!

When the foot brake is applied in an air brake system, a temporary drop in air pressure is expected as air moves from the reservoirs to the brake chambers to apply the brakes.

• This is a normal operational characteristic.
• The pressure should then stabilize.
• Excessive or continuous drop indicates a leak.

Memory trick: Air power for brakes means pressure will bow, but then it will hold, steady and slow.

This test checks the air compressor's ability to quickly build air pressure from a specified minimum to maximum within a set time limit, ensuring adequate air supply for braking.

• Engine at operating RPM.
• Pressure build-up from 85 to 125 psi.
• Maximum allowable time is typically 45 seconds for combination vehicles.
• Failure indicates a problem with the compressor or leaks.

Memory trick: Compressor's quick build-up, safety's strong hold, less than 45 seconds, a story untold.

A bulge in an air brake line indicates a compromised hose structure, where the inner layers have failed. This is a critical defect that can lead to sudden hose rupture and loss of air pressure.

• Indicates imminent hose failure.
• Can lead to sudden loss of brake function.
• Requires immediate vehicle removal from service.
• Never attempt temporary repairs like taping.

Memory trick: A bulging hose, a silent scream, for safety's sake, halt the dream.

The emergency air line (red) connects the tractor's emergency air supply to the trailer's emergency brake system, allowing for automatic braking if air pressure is lost.

• Always connect red to red.
• Supplies air to release trailer spring brakes.
• Activates trailer brakes if pressure drops or lines separate.

Memory trick: Red-to-red, blue-to-blue, keeps your trailer braking true.

After the trailer is supported by its landing gear, the air lines and electrical cable are disconnected to sever the operational link between the tractor and trailer.

• Ensures trailer stability before disconnection.
• Prevents damage to lines if tractor moves prematurely.
• Part of a systematic uncoupling procedure.

Memory trick: Park, Prop, Pull the Plugs, then Part ways.

After coupling, the fifth wheel release arm must be fully pushed in and often secured with a safety latch or clip to prevent accidental activation and trailer separation.

• Prevents accidental uncoupling.
• Often involves a safety latch or pin.
• Critical final check before driving.

Memory trick: Lock the Latch, Lest you Crash.