trailer brakes won't hold

Discussion in 'Freightliner Forum' started by BHarbinson74, May 5, 2022.

  1. BHarbinson74

    BHarbinson74 Bobtail Member

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    Posting on behalf of someone else and it's got me scratching my head too.
    Thought I'd pick the brains of those more knowledgeable.

    Truck: 2012 Cascadia 125 day cab
    Issue: Trailer brakes have been measured and are adjusted correctly. If trailer brakes are set he can pull forward and the wheels still spin. They don’t feel like they are working right while driving either. He has replaced the tractor protection valve and it didn’t fix the issue. The truck doesn't have a Johnny Bar so he hooked the trailer to a different truck with a Johnny bar and the brakes work like they are supposed to. This would indicate that the issue is on the truck side. Any suggestions?
     
    truckdriver31 Thanks this.
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  3. Big Road Skateboard

    Big Road Skateboard Road Train Member

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    Maybe a quick release valves on the supply line isn't exhausting air, or the supply line is kinked.

    Have him release the brakes, let it air up thr trailer, then set. Remove the red glad hand and see if there's air
     
    Oxbow Thanks this.
  4. GYPSY65

    GYPSY65 Road Train Member

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    Didn’t read the entire post and it answered my thought
     
    Last edited: May 6, 2022
  5. Shawn2130

    Shawn2130 Heavy Load Member

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    Sounds like an issue we are trying to fix with one of our dump trucks.

    Doesn’t park right and doesn’t brake right.

    Brakes are adjusted and there’s 3/4 lining left.

    It’s been an on going issue that’s never been solved yet.
     
  6. truckdriver31

    truckdriver31 Road Train Member

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    Are airlines hooked up correctly. Red to red blue to blue
     
  7. Around the block

    Around the block Bobtail Member

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    May 6, 2022
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    Might have a broken brake chamber spring or two... Would explain why the hand valve will hold it back, but dynamiting them won't. Not uncommon. Smack the chamber with a hammer and listen for anything rattling in there.
     
    truckdriver31, Shawn2130 and lester Thank this.
  8. gentleroger

    gentleroger Road Train Member

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    Does it have a trailer hold switch?
     
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  9. North Pole Nightmare

    North Pole Nightmare Light Load Member

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    Did you find the problem?I normally start at the wrong end of the truck and check everything,until I find it,so I'm not much help on this one.
     
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  10. BHarbinson74

    BHarbinson74 Bobtail Member

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    Oct 7, 2020
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    there is air coming out of the red line as well as the blue when you press on the brake
     
    truckdriver31 Thanks this.
  11. BHarbinson74

    BHarbinson74 Bobtail Member

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    Oct 7, 2020
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    Yes, the air lines are hooked up right.
     
    truckdriver31 Thanks this.
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