CCDL Permit Prep

Vehículos combinados · página 2 de 3

Preguntas de Vehículos combinados 21–40

Parte del banco de 58 preguntas de Vehículos combinados. Cada respuesta cita el Manual CDL de FMCSA o la norma federal de donde proviene.

Practicar estas en una sesión cronometrada

  1. Traducción en revisión. Se muestra el contenido actualizado en inglés. How do you test that the trailer emergency brakes work?

    • AApply the foot brake at speed
    • BCharge the system, pull the air supply control, then pull gentlyCorrecta
    • CSet the parking brake and rev the engine
    • DDisconnect the electrical cord

    Charge the trailer air brake system and confirm the trailer rolls freely. Stop, pull out the trailer air supply control, then pull gently with the tractor to check that the trailer emergency brakes are on.

    FMCSA Commercial Driver License Manual · Section 6.5.2: Test Trailer Emergency Brakes · verificado 2026-09-07

  2. Traducción en revisión. Se muestra el contenido actualizado en inglés. After positioning a sliding fifth wheel, what must you verify before travel?

    • AThat all locking pins are present and locked in placeCorrecta
    • BThat the trailer paint lines up with the tractor
    • CThat the brake timing changes
    • DThat the trailer lights are unplugged

    A sliding fifth wheel must have all locking pins present and locked in place. Also verify the position allows the tractor frame to clear the landing gear during turns.

    FMCSA Commercial Driver License Manual · Section 6.5.1: Sliding Fifth Wheel · verificado 2026-09-07

  3. Traducción en revisión. Se muestra el contenido actualizado en inglés. After coupling, how should you check the connection is locked?

    • ACheck the tire pressure on the trailer
    • BLook at the trailer's rear doors
    • CSound the horn and listen for rattles
    • DPull forward gently against the trailer brakesCorrecta

    A gentle pull against locked trailer brakes checks that the connection resists separation. Secure the tractor and also inspect for no plate gap, jaws around the kingpin shank, and a secured locking mechanism. The tug does not replace those visual checks.

    Oregon DMV Commercial Driver Manual · 6.2.4 Air-lines; 6.2.5 Hose Couplers; 6.4.1 Coupling; 6.4.2 Uncoupling · verificado 2026-09-07

  4. Traducción en revisión. Se muestra el contenido actualizado en inglés. Before uncoupling, what must be done with the landing gear?

    • AKeep it raised until the tractor leaves
    • BLower it to firm support on suitable ground, following the loaded or empty trailer procedureCorrecta
    • CRemove the crank handle before lowering
    • DLeave the legs above the ground

    Support the trailer before withdrawing the tractor. Use firm ground contact and the applicable loaded/empty procedure; maximum extension is not the goal. Check support again with the tractor frame partly underneath.

    Oregon DMV Commercial Driver Manual · 6.2.4 Air-lines; 6.2.5 Hose Couplers; 6.4.1 Coupling; 6.4.2 Uncoupling · verificado 2026-09-07

  5. Traducción en revisión. Se muestra el contenido actualizado en inglés. Why is a loaded combination vehicle more likely to roll over than a car?

    • AIts steering is geared more quickly
    • BIts brakes apply on fewer axles
    • CIts center of gravity sits much higherCorrecta
    • DIts tires are narrower per axle

    With more cargo piled higher, the combination vehicle's center of gravity moves higher from the road and the vehicle becomes easier to turn over. Drive slowly around corners and on ramps, and avoid quick lane changes, especially when fully loaded.

    FMCSA Commercial Driver License Manual · Section 6.1.1: Rollover Risks · verificado 2026-09-08

  6. Traducción en revisión. Se muestra el contenido actualizado en inglés. What causes a trailer jackknife?

    • ATrailer wheels lock and the trailer begins to swing aroundCorrecta
    • BThe kingpin releases while driving
    • CThe landing gear drags on the road
    • DThe steer tires lose air pressure

    When trailer wheels lock, the trailer can swing around because the locked wheels lose traction. The manual advises releasing the brakes to regain traction; once the wheels grip the road, the trailer can begin to follow the tractor and straighten.

    FMCSA Commercial Driver License Manual · Section 6.1.5: Prevent Trailer Skids · verificado 2026-09-08

  7. Traducción en revisión. Se muestra el contenido actualizado en inglés. When backing a tractor-trailer, which way do you steer to move the trailer left?

    • ATurn the wheel left throughout
    • BTurn the wheel right at firstCorrecta
    • CHold the wheel straight and reverse
    • DAlternate quickly left and right

    When backing a trailer, the steering wheel moves the trailer in the opposite direction. To move the trailer left, initially turn the wheel right; as the trailer starts to turn, steer the other way to follow its path and make corrections slowly.

    FMCSA Commercial Driver License Manual · Section 6.1.7: Backing with a Trailer · verificado 2026-09-08

  8. Traducción en revisión. Se muestra el contenido actualizado en inglés. What must you check about the trailer's air line connections?

    • AThat the lines are pulled taut
    • BThat the couplers are painted
    • CSeals seat firmly and lines have enough slack for turnsCorrecta
    • DThat one line is left open

    Air lines must be properly connected to the glad hands, have no leaks, and be secured with enough slack for turns. Air and electrical lines also must not hit moving parts or show damage.

    FMCSA Commercial Driver License Manual · Sections 6.4.1 and 6.5.1: Air and Electrical Lines · verificado 2026-09-07

  9. Traducción en revisión. Se muestra el contenido actualizado en inglés. Why must you allow more space and time when a combination vehicle changes lanes?

    • AIts trailer brakes release late
    • BIts mirrors sit lower on the door
    • CIts engine responds more slowly
    • DIt is longer and its rear units amplify movement during the lane changeCorrecta

    Combination vehicles are longer, and a quick steering movement can create rearward amplification, so the trailer's movement can be greater than the tractor's. Allow room for the whole unit and steer gently and smoothly.

    FMCSA Commercial Driver License Manual · Section 6.1.2: Steer Gently · verificado 2026-09-08

  10. Traducción en revisión. Se muestra el contenido actualizado en inglés. What does the trailer air supply valve do?

    • ACharges the trailer and releases its brakesCorrecta
    • BApplies the tractor brakes only
    • CAdjusts the fifth wheel position
    • DControls the trailer lights

    FMCSA Section 6.2.3 says pushing the trailer air-supply control in supplies air to the trailer; pulling it out shuts off the air and applies the trailer emergency brakes. The control may be a knob or lever depending on the vehicle.

    FMCSA Commercial Driver License Manual · Section 6.2.3: Trailer Air Supply Control · verificado 2026-09-08

  11. Traducción en revisión. Se muestra el contenido actualizado en inglés. What must you check underneath the trailer after coupling?

    • AThat the mudflaps are removed
    • BThe color of the underside
    • CThat the axles are freshly greased
    • DNo gap between the fifth-wheel plate and the trailer apronCorrecta

    A visible plate gap indicates an improper coupling; a kingpin sitting on top of closed jaws is one possible cause. Do not drive until corrected and rechecked. Inspect engagement around the shank and the locking mechanism too.

    Oregon DMV Commercial Driver Manual · 6.5.1 Combination walk-around inspection; 6.5.2 brake checks · verificado 2026-09-07

  12. Traducción en revisión. Se muestra el contenido actualizado en inglés. What should you look for when inspecting the locking jaws?

    • AClosed around the shank, not the head, of the kingpinCorrecta
    • BOpen wide for airflow
    • CPainted a contrasting color
    • DLoose enough to rotate

    The locking jaws must close around the shank, not the head, of the kingpin. The release arm must be seated and the safety latch or lock engaged.

    FMCSA Commercial Driver License Manual · Section 6.5.1: Coupling System Areas · verificado 2026-09-07

  13. Traducción en revisión. Se muestra el contenido actualizado en inglés. What is the electrical pigtail on a combination vehicle?

    • AThe cable for the trailer's radio
    • BThe line carrying brake air
    • CThe cable powering the trailer's lightsCorrecta
    • DThe chain securing the dolly

    FMCSA Section 6.4 says to plug the electrical cord into the trailer, fasten its safety catch, and check the electrical line for damage and clearance from moving parts. The cord provides the trailer's electrical connection.

    FMCSA Commercial Driver License Manual · Section 6.4.1: Coupling Tractor-Semitrailers, Step 14 · verificado 2026-09-08

  14. Traducción en revisión. Se muestra el contenido actualizado en inglés. After adjusting a trailer's tandem release, what should you confirm?

    • AThe kingpin releases
    • BThe trailer becomes lighter
    • CThe tractor loses its brakes
    • DThe locking pins are locked and the release arm is securedCorrecta

    FMCSA Section 11.4.2 says to make sure the tandem locking pins are locked in place and the release arm is secured after the tandem assembly is adjusted.

    FMCSA Commercial Driver License Manual · Section 11.4.2: Side of Trailer (Tandem Release Arm/Locking Pins) · verificado 2026-09-08

  15. Traducción en revisión. Se muestra el contenido actualizado en inglés. What should you confirm after sliding the tandems?

    • AThe locking pins are fully engagedCorrecta
    • BThe trailer doors are open
    • CThe mudflaps are level
    • DThe pigtail is disconnected

    FMCSA Section 11.4.2 says to confirm that the tandem locking pins are locked in place and the release arm is secured after the tandem assembly is adjusted.

    FMCSA Commercial Driver License Manual · Section 11.4.2: Side of Trailer (Tandem Release Arm/Locking Pins) · verificado 2026-09-08

  16. Traducción en revisión. Se muestra el contenido actualizado en inglés. Before uncoupling, why must the driver check the parking surface?

    • ATo make sure it can support the trailer's weightCorrecta
    • BTo help the paint cure evenly
    • CTo make the trailer lights brighter
    • DTo reduce tire wear during the stop

    Before uncoupling, make sure the parking surface can support the trailer's weight. Keep the tractor lined up with the trailer because pulling out at an angle can damage landing gear.

    FMCSA Commercial Driver License Manual · Section 6.4.2: Uncoupling Tractor-Semitrailers · verificado 2026-09-07

  17. Traducción en revisión. Se muestra el contenido actualizado en inglés. When trailer wheels lock up and the trailer swings around, what is this type of jackknife called?

    • AA parking jackknife
    • BA trailer jackknifeCorrecta
    • CA tractor-only jackknife
    • DA reversing jackknife

    FMCSA Section 6.1.5 says that when trailer wheels lock up, the trailer tends to swing around; this type of jackknife is often called a trailer jackknife.

    FMCSA Commercial Driver License Manual · Section 6.1.5: Prevent Trailer Skids · verificado 2026-09-08

  18. Traducción en revisión. Se muestra el contenido actualizado en inglés. How do you correct a beginning tractor jackknife?

    • AApply the trailer hand valve
    • BBrake harder to stop sooner
    • CSteer sharply into the skid
    • DRelease the brakes so the wheels rollCorrecta

    FMCSA Section 2.19.2 says to stop braking so the rear wheels roll again, then counter-steer as the vehicle returns to course. Follow the manual's direction and regain control only when safe.

    FMCSA Commercial Driver's License Manual (July 2014) · 2.18.5 ABS on the Tractor Only or Only on the Trailer · verificado 2026-09-25

  19. Traducción en revisión. Se muestra el contenido actualizado en inglés. When traveling near other vehicles, what does the FMCSA manual recommend?

    • AAvoid driving alongside others when possibleCorrecta
    • BStay beside them through a lane change
    • CAssume the other driver can always see you
    • DKeep no space so traffic cannot pass

    FMCSA Section 2.7.3 says commercial vehicles have little side space. Avoid driving alongside others when possible. If you must, keep as much space as possible and adjust position so the other driver can see you.

    FMCSA Commercial Driver License Manual · Section 2.7.3: Space to the Sides · verificado 2026-09-08

  20. Traducción en revisión. Se muestra el contenido actualizado en inglés. What should you check about the trailer's mudflaps?

    • ARemoved for highway use
    • BPainted to match the trailer
    • CPresent, secure and not draggingCorrecta
    • DFolded up when loaded

    FMCSA Section 11.2.6 says to check that splash guards or mud flaps are not damaged and are mounted securely. Section 2.1.5 also says they should be present, properly fastened, not dragging, and not rubbing tires.

    FMCSA Commercial Driver License Manual · Section 11.2.6: Rear of Vehicle (Splash Guards); Section 2.1.5: Rear of Vehicle · verificado 2026-09-08

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