Practice Test Geeks(310t) Truck and Coach Technician Certification Practice Test
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Air Brake Systems Diagnosis 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 Brake Systems Diagnosis flashcards as text

  1. A truck's air dryer purge valve is constantly exhausting air. What is the MOST likely cause?

    Answer: Excessive compressor oil carry-over clogging the desiccant

    Excessive oil carry-over from a worn compressor saturates the desiccant cartridge, reducing its efficiency and causing the purge cycle to vent continuously.

  2. During a brake application, the left front wheel locks up while the right front remains normal. This symptom MOST likely indicates:

    Answer: A stuck open ABS modulator valve on the left front

    A stuck open ABS modulator inlet valve prevents pressure release to the affected wheel, causing it to lock while the ABS system fails to cycle.

  3. When performing a static leakage test on a straight truck, the maximum allowable pressure drop per minute for the service brake system is:

    Answer: 3 psi

    FMCSA regulations allow a maximum of 3 psi drop per minute for single-vehicle service brake systems during a static leakage test.

  4. A driver reports that the spring brakes apply automatically when going downhill on a long grade. The MOST likely cause is:

    Answer: System air pressure dropping below the low-pressure warning threshold

    If sustained brake application drains the reservoir pressure below approximately 60 psi, the spring brakes automatically apply to prevent brake fade.

  5. What tool is used to accurately measure the push rod stroke of a brake chamber to determine if it exceeds the adjustment limit?

    Answer: Steel ruler applied at full brake application

    A steel ruler placed against the chamber body with the push rod at full application gives the stroke reading that is compared to the maximum stroke limit.

  6. A quick-release valve fails to exhaust air from the brake chambers quickly. Which symptom will the driver notice?

    Answer: Brake drag due to slow pressure release

    A restricted quick-release valve slows pressure exhaust from the chambers, delaying brake release and causing brake drag after the pedal is released.

  7. An S-cam brake assembly shows uneven lining contact, with the leading edge of the lining worn more than the trailing edge. This MOST likely indicates:

    Answer: Weak or broken return springs allowing the cam to over-rotate

    Weak return springs allow the S-cam to rotate beyond its normal position, causing excessive contact at the leading edge and uneven lining wear.