Air Brake Diagnostics Flashcards
What is the first step in diagnosing an air brake system failure?
Recognize the symptoms of failure.
Symptoms may include insufficient braking force, air pressure gauge abnormalities, audible air leaks, inconsistent braking performance, and warning lights.
List the symptoms of air brake system failure.
- Insufficient braking force
- Air pressure gauge abnormalities
- Audible air leaks
- Inconsistent braking performance
- Warning lights on the dashboard
What should be checked first during an initial system check?
Air pressure gauges to ensure the compressor is maintaining the required pressure.
This includes inspecting air tanks for proper air pressure.
What is a common problem that can cause air brake failure?
Air leaks.
Leaks can occur in hoses, valves, or seals.
What are the symptoms of air leaks in an air brake system?
- Sudden loss of air pressure
- Audible air escaping
- Brakes that don’t release properly
- Continuous compressor operation
How can you check for leaks in an air brake system?
Use a soap and water solution to spray over lines and fittings.
Bubbling indicates a leak.
What is the function of the modulating valve in an air brake system?
Helps control the pressure applied to the brake chambers.
Allows for gradual application and release of the brakes.
What are the symptoms of a modulating valve failure?
- Inconsistent braking response
- Brakes not engaging or engaging too hard
What is the function of the quick release valve?
Releases air from the brake chambers when the brake pedal is released.
This allows the brakes to disengage quickly.
What are the symptoms of a quick release valve failure?
- Brakes fail to release properly
- Air pressure loss in the system
What is the role of the safety valve in an air brake system?
Prevents excessive pressure buildup in the system.
Typically set to release air if pressure exceeds a certain threshold.
What are the symptoms of safety valve failure?
- High pressure warnings
- No pressure relief
What does the governor valve do in an air brake system?
Regulates the air compressor’s operation based on system pressure.
What are the symptoms of governor valve failure?
- Continuous compressor operation
- Erratic operation
What is the function of the brake valve (foot valve)?
Controls the flow of air to the brake chambers when the brake pedal is pressed.
What are the symptoms of brake valve failure?
- Delayed or unresponsive braking
- Air pressure inconsistencies
- Spongy pedal feel
What symptoms indicate a compressor and air dryer failure?
- Compressor fails to maintain proper air pressure
- Faulty air dryer leads to moisture buildup
What should be done during a functional and performance testing of the air brake system?
- Perform a static brake test
- Conduct a leak test
- Perform a driving brake test
What is the purpose of final checks and adjustments after diagnosing air brake issues?
Ensure all parts are properly reassembled and the system is sealed.
What should be inspected after replacing faulty components in an air brake system?
- Air pressure at various points
- Brake shoes or pads for wear
- Brake chambers for smooth operation
True or False: A faulty modulating valve can cause brakes to apply too quickly or unevenly.
True
