Podcast
Questions and Answers
What should you do before starting the brake bleed down process?
What should you do before starting the brake bleed down process?
What RPM should the engine be revved to during the governor check?
What RPM should the engine be revved to during the governor check?
1200-1400 RPM
What is the maximum allowable air loss in 1 minute during the 3PSI air loss rate check?
What is the maximum allowable air loss in 1 minute during the 3PSI air loss rate check?
3 PSI
At what PSI should the low air pressure buzzer and light come on?
At what PSI should the low air pressure buzzer and light come on?
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How much air pressure should build to confirm compressor recovery in 45 seconds?
How much air pressure should build to confirm compressor recovery in 45 seconds?
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What is the purpose of tugging against the trailer parking brake during the trailer brake check?
What is the purpose of tugging against the trailer parking brake during the trailer brake check?
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What action should be performed after moving forward 5 mph during the tractor service brake check?
What action should be performed after moving forward 5 mph during the tractor service brake check?
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What should be done at the end of the brake bleed down process?
What should be done at the end of the brake bleed down process?
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The governor will cut out when the air pressure reaches between 120-125 PSI.
The governor will cut out when the air pressure reaches between 120-125 PSI.
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Pump service brake until yellow and red valves pop up between ______ PSI.
Pump service brake until yellow and red valves pop up between ______ PSI.
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Study Notes
Pre-Check Procedures
- Ensure parking brakes are engaged and vehicle placed in 1st gear.
- Keep the vehicle key in your pocket to avoid ignition.
- Use three points of contact when exiting and entering the cab.
- Remove and apply chock blocks to wheels as necessary.
- Always wear a seatbelt while in the cab.
Step 1: Governor Check
- Start engine in neutral and rev to 1200-1400 RPM.
- Build air pressure to 120-125 PSI, ensuring system is fully charged.
- Release parking brakes, observing pressure drop to 100 PSI for governor activation.
- Repeat the revving to confirm governor cut-out.
- Turn off engine, leaving key in ON position for gauge power.
Step 2: 3PSI Air Loss Rate Check
- Release parking brakes and monitor air loss.
- After an initial drop of 5-15 PSI, ensure loss does not exceed 3 PSI in one minute.
Step 3: 4PSI Air Loss Rate Check
- While holding service brake, check air loss.
- After an initial drop of 5-15 PSI, ensure loss does not exceed 4 PSI in one minute.
Step 4: Low Air Pressure Warning Check
- Continuously pump the service brake until low air pressure warning activates between 60-70 PSI.
Step 5: Spring Brake Check
- Pump the service brake until red and yellow valves engage at 20-45 PSI.
Step 6: Compressor Recovery Check
- Start engine in neutral and rev to 1200-1400 RPM.
- Check if air pressure rises from 85-100 PSI within 45 seconds.
- Continue until the system is fully charged and ensure parking brakes are set before leaving the cab.
Step 7: Trailer Parking Brake Check
- With the engine on, release tractor parking brake and attempt to move the vehicle.
- Tug against the trailer parking brake to ensure it holds.
Step 8: Tractor Parking Brake Check
- Release trailer parking brake and test vehicle movement.
- Tug against tractor parking brake to ensure it is functional.
Step 9: Trailer Service Brake Check
- Move the vehicle forward at 5 mph; engage trolley brake to test stopping ability.
- Fully release the trolley brake after the check.
Step 10: Tractor Service Brake Check
- Again moving forward at 5 mph, depress the service brake and ensure the vehicle stops without lateral movement.
After Finishing Brake Bleed Down
- Engage parking brake, shift to lowest gear, and turn off the engine.
- Take the key and exit the cab using three points of contact.
- Always close the door after exiting.
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Description
Test your knowledge on the essential steps for the Brake Bleed Down procedure in Class A CDL. This quiz covers key steps to ensure safety and compliance before operating a vehicle. Perfect for CDL students preparing for their examinations.
