Pre-trip Inspection Procedures Flashcards
6 cards from real Air Brake Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Pre-trip Inspection Procedures flashcards as text
During a pre-trip air brake inspection, at what pressure should the low air pressure warning signal activate?
Answer: Before air pressure drops below 60 psi
The low air pressure warning device must activate before pressure falls below 60 psi, giving the driver time to stop safely before spring brakes engage at approximately 20–45 psi.
What is the correct procedure to test the spring brakes during a pre-trip inspection?
Answer: Charge the system, chock wheels, release service brakes, pull the parking brake knob, and attempt to move the vehicle
With wheels chocked, fully charged system, and service brakes released, pulling the parking brake control should firmly prevent any vehicle movement — confirming the spring brakes are functioning.
How do you test the tractor protection valve during a pre-trip inspection?
Answer: Close the shut-off valves on the rear, reduce trailer air pressure to trigger the valve, and confirm it closes
The tractor protection valve is tested by reducing trailer air pressure (by closing shut-off valves and draining air) until it drops to the activation range, confirming the valve closes to protect tractor air.
What is the acceptable pressure drop rate with service brakes applied during the pre-trip air brake leak test?
Answer: Less than 3 psi per minute for single vehicles; less than 4 psi per minute for combination vehicles
FMCSA/CVSA standards allow a maximum leak rate of 3 psi/min for singles and 4 psi/min for combinations with service brakes applied; anything above is cause for repair.
When inspecting the air compressor belt during a pre-trip, what should you check for?
Answer: Cracks, fraying, proper tension, and correct alignment
The compressor drive belt must be inspected for cracks, wear, fraying, proper tension, and correct alignment to ensure the compressor will maintain adequate air pressure.
During a pre-trip, you notice the air pressure gauge is fluctuating rapidly and erratically. What could this indicate?
Answer: A faulty gauge, a failing compressor governor, or a significant air leak in the system
Rapid erratic gauge fluctuation can indicate a malfunctioning gauge, governor problems causing rapid cycling, or a large leak that makes pressure unstable.