Air Brake leakage PSI's

Discussion in 'Questions From New Drivers' started by dogchimp, Feb 22, 2013.

  1. dogchimp

    dogchimp Medium Load Member

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    Ive noticed my manual, and the practice tests all appear to have different rates for what is acceptable for how fast air brakes should leak, I believe for a dual system combination vehicle, it should be no more then 4 psi per minute, can some one post this info to help me out?
     
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  3. 379exhd

    379exhd Road Train Member

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    Dual air combo brakes applied 4psi with the truck off. And 3 psi with no brake applied and the truck off single is 3psi applied truck off and 2 psi truck off no application
     
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  4. chopper103in

    chopper103in Road Train Member

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    [FONT=Arial,Bold][FONT=Arial,Bold]Test Air Leakage Rate.
    [/FONT]
    [/FONT]
    [FONT=Arial,Bold][FONT=Arial,Bold][/FONT][/FONT]With a fully-charged air
    system (typically 125 psi), turn off the engine,
    release the parking brake, and time the air
    pressure drop. The loss rate should be less than
    two psi in one minute for single vehicles and less
    than three psi in one minute for combination
    vehicles. Then apply 90 psi or more with the brake
    pedal. After the initial pressure drop, if the air
    pressure falls more than three psi in one minute for
    single vehicles (more than four psi for combination
    vehicles), the air loss rate is too much. Check for
    air leaks and fix before driving the vehicle.
    Otherwise, you could lose your brakes while
    driving.
     
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  5. dogchimp

    dogchimp Medium Load Member

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    Aha I can see clearly now where I got confused, thanks guys!
     
  6. 379exhd

    379exhd Road Train Member

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    #### cdl book quotes. I just push the pedal down and hold it. Idt i can put 90 psi to the brakes in my 2000 with the pedal hell pulling the trolly bar all the way down with 135lbs in the tanks i can only get 100 lbs back to the trailer brakes if that. And dogchimp in my comment when i said single i ment single vehicle like a straight truck or a bob tail rig. Hell who checks the air brakes durning a pretrip anyways i mean you only need your brakes to stop...and theyll automatically stop you if the compressor fails so who cares about pretriping them lol. Thats sarcasm i check mine everytime i pretrip my truck...it fails because i have an air leak in my abs valve but the brakes themselves function fine and she stops quick when she needs too
     
  7. tinytim

    tinytim Road Train Member

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    I'd like to meet the person that can tell if that little dial moved 3 psi.
     
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  8. 379exhd

    379exhd Road Train Member

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    Lmfao good point:biggrin_25514:
     
  9. dibstr

    dibstr Road Train Member

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    And I am still in Pursuit of a truck-tractor/trailer that the pressure does not drop more than the allowable when you release the park brakes.

    Best regards
     
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