Questions and Answers
What should you do before starting the brake bleed down process?
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?
3 PSI
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?
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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?
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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.
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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.
