LA CDL Air Brakes study plan

Label each major component of a typical air brake system (compressor, governor, reservoirs, check valves, foot valve, relay valve, slack adjusters, chambers, parking/emergency spring brakes) and state its function in one sentence each.

Trace the path of compressed air from compressor intake through the supply reservoir, foot valve, and brake chambers, and explain what happens at each stop.

Explain the governor's cut-in and cut-out pressures and why the compressor must unload rather than keep pumping.

Describe how the parking/emergency spring brakes apply automatically when air pressure drops, and name the pressure range where the spring begins to overcome air pressure.

Define the normal operating pressure range for a CMV air brake system and write it from memory without notes.

Explain the difference between the supply reservoir and the primary/secondary (dry) reservoirs and why check valves sit between them.

Describe the function of the low-pressure warning device and identify the pressure at which it must activate.

Explain how a leak in the primary circuit affects the secondary circuit and why isolation valves matter.

Identify the components that are lubricated or drained during routine maintenance and state how often each service is typically performed.

Explain what an alcohol evaporator or air dryer does and why moisture control protects the system from freeze-up and corrosion.

Perform and narrate the full in-cab pre-trip air brake check in the correct order: build pressure, check for leaks with engine off, test the low-pressure warning, test the spring brakes, and test the service brakes.

State the acceptable pressure-loss limits for a static leak test (single vehicle and combination vehicle) and the time interval used.

Demonstrate the compressor build-up test and state the minimum pressure build rate required.

Identify the pressure at which the low-pressure warning must sound and the pressure at which the spring brakes must fully apply.

List the visual pre-trip items outside the cab: slack adjuster travel, pushrod angle, chamber condition, hose chafing, and drain valve operation.

Explain what a brake adjustment check measures and describe how to measure pushrod travel on a typical chamber.

Describe how to test the service brakes at low speed and what a pull to one side or a delayed stop indicates.

Explain how load affects stopping distance and why the same pedal pressure does not produce the same deceleration empty and loaded.

Describe proper braking technique on long downgrades, including snubbing and the reason for not riding the brakes.

Explain how brake fade develops from overheating and what the driver should do when it begins.

Describe how to use the parking/emergency spring brakes for parking and explain why the system must not be relied on for routine stopping.

Explain how to check that the system is holding pressure while driving and what a slow pressure loss in motion signals.

List the warning signs of an air brake problem: low-pressure buzzer or light, pressure dropping under braking, hissing, slow build-up, and a spongy or long pedal.

Explain what to do if the low-pressure warning activates while driving, including downshifting, using engine braking, and finding a safe stop.

Describe the procedure for a total air loss and explain why the spring brakes apply rather than release.

Perform the static leak test on a real or simulated vehicle, record the pressure drop over the required interval, and compare it to the limit.

Distinguish between a leak that only appears with the brakes applied and one that appears with the brakes released, and explain what each suggests.

Describe how to locate a leak by sound and by soap solution, and list the common leak points (fittings, hoses, drain valves, chambers, foot valve).

Explain how a failed compressor or governor causes chronic low pressure and what symptoms the driver notices first.

Describe when a vehicle must be placed out of service for an air brake defect and why a driver should not simply add air and continue.

Re-explain each component and each inspection step from memory, filling any gaps found in earlier weeks.

Explain the relationship between the governor, compressor, and low-pressure warning as one continuous system rather than separate facts.

Describe how a failed slack adjuster or a stuck relay valve changes braking behavior and which warning sign appears first.

Walk through a combination-vehicle pre-trip air brake check, including the trailer protection valve and trailer spring brake test.

Answer 40 practice questions across all five domains and identify which domain produced the most errors.

Re-drill the weakest domain identified in week 7 until practice accuracy exceeds 90 percent.

Recite the full in-cab air brake inspection and the emergency procedures from memory under time pressure.

Review all pressure specifications, leak-test limits, and warning thresholds in a single consolidated sheet.

Complete two full-length timed practice exams and compare scores to confirm readiness.

Write a final list of any remaining uncertain facts and resolve each one before test day.