MA CDL Air Brakes study plan

Label every major component of a dual-circuit air brake system (compressor, governor, reservoirs, check valves, foot valve, relay valve, brake chambers, slack adjusters) on a blank diagram you draw yourself, scoring at least 90% accuracy.

Explain in writing how the compressor and governor cycle between cut-in and cut-out pressure, including the typical pressure range and what happens when the governor fails.

Trace the path of air from the compressor to a front and a rear brake chamber, naming each component and valve the air passes through and its function.

Describe the difference between service, parking, and emergency brake application in terms of which air circuits and springs are involved.

Compare the two separate air circuits of a dual air brake system: identify which components each circuit typically supplies and why the circuits are isolated.

Explain the role of check valves, the inversion valve, and the spring brake priority valve in protecting against a total or partial air loss.

Describe how a spring brake chamber applies and releases, including what happens when air pressure is lost or the parking brake is set.

List at least five safety features of dual systems (e.g., low-pressure warning, spring brakes, isolation) and state what each protects against.

Build a written pre-trip checklist for air brake components in the correct inspection order, from engine off to final brake test.

Demonstrate aloud (record yourself) the air brake portion of a pre-trip inspection, including checking slack adjusters, push rods, brake chambers, hoses, and drums.

Identify at least three common defects visible during inspection (cracked hose, loose chamber clamp, excessive push-rod travel) and state the correct rejection criteria.

Explain how to check that the parking brake and service brakes hold, and what you would do if a defect is found.

State the standard static leak test procedure and the acceptable pressure-loss limits for a single vehicle and for a combination vehicle.

Describe the applied-pressure leak test: how to perform it, what gauges to watch, and the maximum allowable loss.

Explain the low-pressure warning test: at what pressure the warning must activate and how to verify both the audible and visual warnings.

Describe the spring brake (parking brake) test and the correct sequence for the complete air brake inspection sequence used during a skills test.

Explain the correct technique for normal stops with air brakes, including how to avoid over-braking and how to use light, progressive pressure.

Describe how to check brake response after starting the engine and before moving, and why a brake check is required after any long stop.

Explain how to use the trailer hand valve and why it should not be used for parking.

Describe how to judge stopping distance at highway speed and how load weight and road surface change it.

Explain the correct technique for descending a long downgrade: gear selection before the descent, use of engine braking, and controlled service brake application.

Describe the danger of continuous brake application (brake fade) and how to recognize and recover from it.

State the correct action when brakes fail on a downgrade, including use of emergency escape ramps and engine braking.

Describe how to use the trailer supply valve and spring brakes in an emergency stop situation.

List the warning devices on an air brake system (low-pressure warning buzzer/light, gauges, wig-wag) and state the exact conditions that trigger each.

Explain what to do when the low-pressure warning activates while driving, including safe stopping and the decision not to continue.

Diagnose three common malfunctions (compressor failure, governor failure, leak in a circuit) from symptoms and state the safe response for each.

Re-run the full leak and pressure test sequence from memory and score yourself against the limits from week 4.

Complete a full-length timed practice exam across all seven domains and score at least 85%.

Review every missed question, write the correct reasoning, and re-test those items until you answer them correctly twice.

Recite the pre-trip air brake sequence and all leak-test limits without notes.

Complete a final verbal walkthrough of a downgrade and an emergency brake failure scenario.