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Trailer parking brakes take long to release

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by razor1983, Feb 7, 2022.

  1. Feb 7, 2022 #1
    razor1983

    razor1983 Medium Load Member

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    I recently changed the dolly on the trailer. The new one takes much longer to release the parking brakes after supplying air. Depends on how much air is left in the system, it takes 3- 6 minutes to release the trailer parking brakes.

    Is this a faulty valve? Or just how the air system was setup?
     
    razor1983, Feb 7, 2022
    razor1983, Feb 7, 2022
    #1
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  3. Feb 7, 2022 #2
    Val_Caldera

    Val_Caldera Road Train Member

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    What's The OUTSIDE Temperature?
    FULL AIR In Tractor Tanks?
    Air Tank(s)/Water Tanks BLED?
    Could Be "Faulty Valve".
    No Mechanics On Site?

    I'm Grasping.
     
    Val_Caldera, Feb 7, 2022
    Val_Caldera, Feb 7, 2022
    #2
  4. Feb 7, 2022 #3
    razor1983

    razor1983 Medium Load Member

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    Its warm outside
    With full tanks it takes 2-3 minutes, with empty tanks 5-8 minutes.
    In the winter I bleed the air tanks every night.
    Which valve could be faulty? Air distribution or quick release?

    the old trailer tandem used to release the parking brakes within seconds of air reaching 80-100 psi. So I don’t think its a problem with air supply from the truck
     
    razor1983, Feb 7, 2022
    razor1983, Feb 7, 2022
    #3
  5. Feb 7, 2022 #4
    Goodysnap

    Goodysnap Road Train Member

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    I would say you have leaks on the trailer or dolly emptying the air tanks. Install a cheap pressure gauge in the drain and see how long it takes to bleed off. Soap and water the fittings and valves/tank.

    If the tank is full- time the release and or check the pressure at the E brake valve signal line. If they are still slow, replace the valve. Most systems may fill the tank thru the valve if the valve is mounted on the tank. So, watching the pressure in the tank will tell you alot.
     
    Goodysnap, Feb 7, 2022
    Goodysnap, Feb 7, 2022
    #4
    blairandgretchen, spsauerland and razor1983 Thank this.
  7. Feb 7, 2022 #5
    spsauerland

    spsauerland Road Train Member

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    spsauerland, Feb 7, 2022
    spsauerland, Feb 7, 2022
    #5
    QUALITYTRUCK, razor1983 and Dgr Thank this.
  8. Feb 7, 2022 #6
    Dave1837

    Dave1837 Road Train Member

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    This happened to my trailer a few weeks ago, parking brakes released fine, service brakes took 10-15 seconds to supply and release. There's a valve on the back of the air can that controls air flow, it went bad. I lost all service brakes after a bit
     
    Dave1837, Feb 7, 2022
    Dave1837, Feb 7, 2022
    #6
    86scotty Thanks this.
  9. Feb 8, 2022 #7
    razor1983

    razor1983 Medium Load Member

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    so if I understand this right, changing to a “spring brake priority valve” will release the parking brakes quicker?
     
    razor1983, Feb 8, 2022
    razor1983, Feb 8, 2022
    #7
  10. Feb 8, 2022 #8
    spsauerland

    spsauerland Road Train Member

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    West Harrison, In
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    Yes
     
    spsauerland, Feb 8, 2022
    spsauerland, Feb 8, 2022
    #8
    razor1983 Thanks this.
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