Practice Test Geeks(310t) Truck and Coach Technician Certification Practice Test
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Air Brakes and Braking Systems Flashcards

7 cards from real 310T practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Air Brakes and Braking Systems flashcards as text

  1. What type of valve modulates air pressure to each wheel independently during ABS activation?

    Answer: Modulator valve (ABS solenoid valve)

    ABS modulator (solenoid) valves cycle between hold, dump, and reapply modes to control wheel slip at each monitored axle end.

  2. In a dual-circuit air brake system, which reservoir is pressurized first by the compressor?

    Answer: Wet (supply) tank

    Air from the compressor flows first into the wet (supply) tank where moisture collects, then through check valves into the primary and secondary circuit reservoirs.

  3. What is the minimum air pressure at which the low-pressure warning device must activate per FMCSA regulations?

    Answer: 60 psi

    FMCSA (49 CFR 393.51) requires the low air pressure warning to activate before reservoir pressure falls below 60 psi.

  4. A relay valve is used in air brake systems primarily to:

    Answer: Shorten brake application and release time for remote chambers

    Relay valves use a small control signal from the brake treadle to open a local large-volume air supply to remote brake chambers, reducing lag time.

  5. On a combination vehicle, which valve automatically closes to protect the tractor air supply if trailer air pressure drops rapidly?

    Answer: Tractor protection valve

    The tractor protection valve senses a sudden drop in trailer supply line pressure and shuts off air flow to the trailer, protecting tractor system pressure.

  6. What is the function of the inversion (fail-safe) valve used with spring brake chambers?

    Answer: Inverts the pressure signal so spring brakes apply when service pressure is lost

    An inversion valve routes service brake air to release spring brakes when the park circuit fails, using the inverse relationship between circuits to maintain brake control.

  7. Brake fade on a heavily loaded truck descending a long grade is MOST likely caused by:

    Answer: Heat buildup reducing friction between lining and drum

    Sustained braking generates heat that raises drum and lining temperatures, reducing the coefficient of friction and causing fade.