CCDL Permit Prep

Frenos de aire · página 4 de 4

Preguntas de Frenos de aire 61–67

Parte del banco de 67 preguntas de Frenos de aire. Cada respuesta cita el Manual CDL de FMCSA o la norma federal de donde proviene.

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  1. Traducción en revisión. Se muestra el contenido actualizado en inglés. What does a modulating control valve let a driver do?

    • ADrain the wet tank from the cab
    • BRaise the governor cut-out pressure
    • CApply the spring brakes graduallyCorrecta
    • DDisconnect the trailer air supply

    FMCSA Section 5.1.15 says a modulating control valve lets the driver apply the spring brakes gradually, including when the service brakes fail.

    FMCSA Commercial Driver License Manual · Section 5.1.15: Modulating Control Valves · verificado 2026-09-08

  2. Traducción en revisión. Se muestra el contenido actualizado en inglés. About how much distance does brake lag add at 55 mph?

    • ANone, lag affects only parked vehicles
    • BRoughly 4 feet
    • CRoughly 200 feet
    • DRoughly 32 feetCorrecta

    Air takes about half a second to travel the lines and act on the brakes, and at 55 mph the vehicle covers around 32 feet in that time. Hydraulic brakes on a car have no equivalent delay.

    FMCSA 2005 CDL Testing System Model Manual (July 2014) · Section 5.4.4 — Brake Lag; Oregon Manual § 5.4.4 cross-check · verificado 2026-09-19

  3. Traducción en revisión. Se muestra el contenido actualizado en inglés. Why can repeated air-brake applications with little release time become dangerous?

    • AThey can consume air faster than the compressor replaces itCorrecta
    • BThey cool the drums too quickly and crack them
    • CThey force the governor into permanent cut-out
    • DThey reverse the flow through the check valves

    Each application uses reservoir air. Excessive repeated applications can lower pressure and reduce the reserve needed for braking; compressor recovery is not guaranteed.

    Oregon DMV Commercial Driver Manual · 5.1.7 The Brake Pedal; 5.4.7 Low Air Pressure · verificado 2026-09-07

  4. Traducción en revisión. Se muestra el contenido actualizado en inglés. During the static air-leak test shown, which stated limits are correct?

    • ALess than 3 psi in one minute for a single vehicle; less than 4 psi for a combination vehicle
    • BLess than 5 psi in one minute for a single vehicle; less than 8 psi for a combination vehicle
    • CLess than 2 psi in five minutes for any vehicle, single or combination
    • DLess than 2 psi in one minute for a single vehicle; less than 3 psi for a combination vehicleCorrecta

    For the static test, the manual states less than 2 psi in one minute for a single vehicle and less than 3 psi for a combination vehicle. The applied test has different limits: 3 psi for a single vehicle and 4 psi for a combination vehicle.

    FMCSA-hosted Commercial Driver License Manual (July 2014) · 5.3.3 — Test Air Leakage Rate · verificado 2026-09-29

  5. Traducción en revisión. Se muestra el contenido actualizado en inglés. The low-air warning shown activates while driving. You must:

    • AStop safely before the spring brakes applyCorrecta
    • BContinue to the next truck stop
    • CPump the brakes to rebuild air
    • DShift to neutral and coast

    Stop safely while you still have controlled braking. Continued air loss can cause spring-brake application. Do not wait for the automatic application or pump the brakes to try to build air.

    Oregon DMV Commercial Driver Manual · 5.3.3 Final Air Brake Check; 5.1.11 Low Air Pressure Warning · verificado 2026-09-07

  6. Traducción en revisión. Se muestra el contenido actualizado en inglés. With a fully charged system, engine off and parking brake released, the air pressure loss for a single vehicle should be less than how many psi in one minute?

    • A2 psiCorrecta
    • B3 psi
    • C5 psi
    • D10 psi

    The manual says the loss rate should be less than two psi in one minute for single vehicles and less than three for combination vehicles.

    FMCSA Commercial Driver's License Manual (July 2014) · 5.1.x Test Air Leakage Rate (Section 5.3.3 test uses different conditions) · verificado 2026-09-25

  7. Traducción en revisión. Se muestra el contenido actualizado en inglés. What does an air compressor that never cuts out suggest?

    • AA governor or system fault needing repairCorrecta
    • BA correctly loaded air system
    • CCold weather operation of the dryer
    • DNormal behavior on a long grade

    The governor should unload or stop compressor pumping at the vehicle's specified cut-out pressure. Pressure that keeps rising or a compressor that never unloads indicates a governor or air-system fault that needs repair before driving.

    FMCSA Commercial Driver License Manual · 5.1.9 and 5.3.3 — Air Compressor Governor · verificado 2026-09-07

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