Air break issue

Discussion in 'Questions From New Drivers' started by sailfish27, Apr 8, 2021.

  1. sailfish27

    sailfish27 Bobtail Member

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    When I do a pre-trip on the air breaks, I lose a good amount of air with the service break depressed. Not so much if I lightly apply pressure.
    Mentioned to mechanic and boss to no avail. Not too worried, though maybe I should be? I'm driving a 6 wheel dump, manual transmission and feel safe.
     
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  3. uncleal13

    uncleal13 Road Train Member

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    Hold down the brakes ( don’t take a break ) maximum pressure, after the gauges stabilize. Time it for two minutes. If you drop more than six pounds in your tanks then you’re out of service.
     
  4. Dennixx

    Dennixx Road Train Member

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    Even less for a straight job I believe.
     
  5. AModelCat

    AModelCat Road Train Member

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    4 PSI on a straight truck I believe. 2 PSI for each additional trailer.
     
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  6. AModelCat

    AModelCat Road Train Member

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    If its just an initial pressure drop then it stabilizes, completely normal.

    Look at the size of all 6 brake chambers and then look at the size of your primary and secondary reservoirs. A full brake application will easily drop the reservoir pressure 10 or 15 PSI.
     
  7. Don379

    Don379 Heavy Load Member

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    sailfish, i noticed you using the word break alot . Did something break? If a it was a weld, i would just break out my welder and run a bead. Call it day
     
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  8. kemosabi49

    kemosabi49 Trucker Forum STAFF Staff Member

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    Our forum rules do not allow correcting other members spelling or grammar errors. Even in a sarcastic way.
     
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  9. sailfish27

    sailfish27 Bobtail Member

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    Wow can't get a little slack for a newbie. Long day really tired
     
    Last edited: Apr 8, 2021
    JolliRoger and Deere hunter Thank this.
  10. sailfish27

    sailfish27 Bobtail Member

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    Got my cdl class b less than a month ago. In school the truck I trained on would hold steady after the initial loss of air. Taught initial drop had to be between 5-15 psi and then no more than 3 psi in one minute.

    The truck I am driving will continuously lose air after the initial loss. Probably more than 10 psi in 30 seconds. In a minute it would probably lose between 20-30 psi.
     
  11. SoulScream84

    SoulScream84 Road Train Member

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    This may sound like a stupid question, but it's a common mistake when testing brakes. Are you pushing the brake completely or just applying pressure, and are you maintaining full pressure throughout the test? I've seen guys who flex their ankle/foot a little throughout the process, and that minor change will keep altering brake pressure thus draining the air more.
     
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