NY CDL Air Brakes flashcards
NY CDL Air Brakes · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Compressor governor
- A device that controls when the air compressor pumps air, cutting in at about 100 psi and cutting out at about 125 psi to maintain system pressure.
- Air dryer
- A component that removes moisture and oil from compressed air before it enters the storage tanks, helping prevent freeze-up and corrosion in the air brake system.
- Slack adjuster
- The lever connecting the brake chamber pushrod to the brake camshaft; it converts pushrod force into camshaft rotation that applies the brake shoes.
- Safety valve
- A valve on the air tank that opens at about 150 psi to release excess pressure and protect the system if the governor fails.
- Brake chamber
- A device that converts compressed air pressure into mechanical force, pushing a rod that moves the slack adjuster and applies the brake.
- Foot valve
- The treadle valve operated by the brake pedal; it meters air pressure from the tanks to the brake chambers in proportion to pedal travel.
- Dual air brake system
- A system with two separate air circuits fed by one compressor, so that a failure in one circuit still leaves the other circuit able to stop the vehicle.
- Primary circuit
- In a standard dual air brake system, the circuit that operates the rear brakes; it has its own reservoir and check valve.
- Secondary circuit
- In a standard dual air brake system, the circuit that operates the front brakes; it is separate from the primary circuit so one failure does not disable both.
- Spring brake
- A parking brake held applied by a strong spring and released by air pressure; it applies automatically when air pressure is lost.
- Check valve
- A one-way valve that allows air to flow in one direction only, preventing air from flowing back and draining a circuit or the compressor.
- Pressure differential valve
- A device that senses a significant pressure difference between the two circuits and triggers a warning to the driver.
- Static leak test
- With the engine off and system charged, hold the brakes and watch the gauge; pressure should not drop more than 3 psi per minute for a single vehicle.
- Low pressure warning test
- With the engine off, pump the brakes to reduce pressure; the warning light and buzzer must activate by 60 psi or the manufacturer's specified pressure.
- Spring brake pop-out test
- Continue releasing air pressure until the parking brake knob pops out; this must occur between 20 and 45 psi on most systems.
- Pushrod stroke check
- With brakes released, mark the pushrod, apply the brakes fully, and measure travel; stroke must not exceed the manufacturer's limit, commonly 1 inch.
- Build-up time check
- With the engine at fast idle, the system should build from 85 to 100 psi within the manufacturer's specified time, typically about 45 seconds.
- Leak detection method
- Apply soapy water to fittings and lines; bubbles forming at a joint indicate an air leak that must be repaired before driving.
- Parking brake control
- The yellow diamond knob; push in to release the spring brakes and pull out to apply them. It also applies automatically when pressure is lost.
- Trailer air supply control
- The red octagon knob that supplies air to the trailer; it pops out automatically at about 45 psi, applying the trailer spring brakes.
- Engine retarder use
- An auxiliary braking device that must be turned off on slippery surfaces, because it can cause the drive wheels to lose traction; it does not replace service brakes.
- Brake pedal pumping
- Pumping the pedal on an air brake vehicle releases air and can reduce braking force; the driver should hold steady pressure instead.
- Trailer hand valve
- A control that applies only the trailer brakes; it should not be used for parking and can cause a jackknife if used while the vehicle is moving.
- Governor cut-in point
- The pressure at which the governor restarts the compressor, about 100 psi, so the system recharges after air has been used.
- Low pressure warning
- A light and buzzer that must activate before pressure drops below 60 psi, warning the driver to stop safely before the spring brakes apply.
- Automatic spring brake application
- As pressure falls to about 20-45 psi, the spring brakes apply automatically, stopping the vehicle if the driver has not already stopped.
- Pressure gauge monitoring
- The driver should check the gauge frequently; a rapid drop while driving indicates a leak or failed component requiring immediate attention.
- Warning system purpose
- A safety device that alerts the driver before air pressure reaches a dangerous level; it supplements but does not replace the pressure gauge.
- Sudden air loss response
- Hold the wheel, keep the vehicle straight, and let the spring brakes slow it while steering to the shoulder; warn traffic with flashers and triangles.
- Service brake failure
- If the service brakes fail, the driver can apply the parking brake gradually to slow the vehicle, being careful not to lock the wheels and skid.
- Frozen air line
- Moisture in the system can freeze and block air flow in cold weather; air dryers and alcohol evaporators help prevent this condition.
- Wet brake drying
- After driving through water, apply light brake pressure at low speed to dry the linings; wet brakes may pull to one side or fail to stop the vehicle.