When I let off brake peddle, trailer brakes still have pressure applied

Discussion in 'Trucks [ Eighteen Wheelers ]' started by BigRod2015, Aug 16, 2016.

  1. BoxCarKidd

    BoxCarKidd Road Train Member

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    It is not dumping the control pressure fast enough for some reason ( blue line). The service brake valve-valves should dump air when the pedal is released. Some trucks have a inline dump valve at the back of the cab to help. As others have said tractor protection valve, foot valve etc. Other people talk about stuff a lot newer than I know much about but start with the simple stuff. Dirt around the plunger on top of a foot valve has cost a lot of money.
     
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  3. DustyRoad

    DustyRoad Road Train Member

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    Primary and Secondary air guages.....are not brake pressure guage....and yes, the bp should aver 50lbs unless a hard brake then its 90lbs....time for someone to point out where the owners manual is there for a reason.

    Anyone driving a truck should at least know which guage does what.
     
  4. DustyRoad

    DustyRoad Road Train Member

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    Obviously this is a safety issue, the driver is not a mechanic. Call a shop near you and take the the truck in for a inspection by a certifed air brake tech....it would be suicide to play with the air system if you know nothing about the guages.
     
  5. BigRod2015

    BigRod2015 Bobtail Member

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    I never said the primary and secondary gauges were brake pressure gauges. And yes i have a brake pressure gauge that shows how much pressure is applied.
     
  6. BigRod2015

    BigRod2015 Bobtail Member

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    Nor did I ask for a safety lecture. If you can't help with the question, then move on. I just asked for ideas on things to look for to correct the issue. And I found it. My return line had a kink in it under the spring by the glad hand.. and I fixed it...
     
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  7. DustyRoad

    DustyRoad Road Train Member

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    Great, now you are a mechanic....just like the million of other truckers that came before you...I was getting concerned you were one of those steering wheel holders.

    BTW...what kind of tractor is it?
     
  8. Blackshack46

    Blackshack46 Road Train Member

    Not sure if that's towards me, but I was being a ######## in my comment. I was implying the OP was looking at air pressure gauges, thinking they're brake pressure gauges. Nobody, I mean nobody else questioned that. Hence I asked if anybody actually read the post or skimmed it.
     
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  9. Blackshack46

    Blackshack46 Road Train Member

    But you did, and I quote Screenshot_2016-08-17-19-01-49.png
    Say that you have a trailer air pressure gauge which just happens to be about normal operating pressure of a primary or secondary air pressure gauge.

    You will never have 120-130 brake psi unless you put your foot through the floor.
     
  10. BigRod2015

    BigRod2015 Bobtail Member

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    After cleaner out filter and replacing return line, it started back doing it again.. I crawled around umfer the truck and could hear a small air leak. I tracked it down to a rust spot on the secondary tank, between the tank and cross member of which there is a man made hole there I put my finger in and could feel the air. So now I have to get a new tank or have this one fixed. Would this small air leak cause such a delay in the air dumping when I let off the brake peddle? Or could I now be looking at two different issues? 20160817_191754.jpg 20160817_191542.jpg 20160817_220341.jpg
     
  11. Skate-Board

    Skate-Board Road Train Member

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    It's the relay valve on the trailer. I went through the same thing. @Cat sdp knew my problem. Also, your trailer may be on the recall list to get it replaced for free.

    Here's the list and link below.

    http://www.overdriveonline.com/more...drive&ust_id=2d01cfda13dc3c84bd8153c464618afe


    • 2016 Manac flatbed
    • 2017-2018 Manac van trailer
    • 2014-2016 Polar Tank DOT 406 tank trailer
    • 2014-2016 Polar Tank DOT 407 tank trailer
    • 2014-2016 Polar Tank DOT 412 tank trailer
    • 2014-2015 Polar Tank MC 331 tank trailer
    • 2014-2016 Polar Tank non-code tank trailer
    • 2014-2016 Heil crude trailer
    • 2014-2016 Heil dry bulk trailer
    • 2014-2016 Heil flatbed
    • 2014-2016 petroleum pull trailer
    • 2014-2016 East flatbed
    • 2014-2016 East flatbed tipper
    • 2014-2016 East frame dump
    • 2004-2016 Hyundai Translead chassis
    • 2004-2016 Hyundai Translead container
    • 2004-2016 Hyundai Translead van reefer
    • 2004-2016 Hyundai Translead van trailer


    • 2015-2017 Brenner liquid tank
    • 2015-2016 Cheetah Bridgemaster chassis
    • 2016 Cheetah curtainside flatbed
    • 2015-2016 Cheetah extendable chassis
    • 2015 Cheetah flatbed
    • 2014-2016 Cheetah gooseneck chassis
    • 2015-2016 Cheetah straight frame chassis
    • 2015-2017 Fontaine Revolution
    • 2015-2017 Great Dane dry van
    • 2015-2017 Great Dane reefer
    • 2015-2017 Great Dane flatbed
    • 2014-2016 Hackney beverage trailers
    • 2014-2016 Kindron reefer trailers
    • 2015, 2017 Strick tandem axle van trailers
    • 2015-2017 Transcraft platform trailers
    • 2014-2016 Utility dry van trailers
    • 2014-2016 Utility flatbed trailers
    • 2014-2016 Utility reefer trailers
    • 2015-2016 Vermeer TR620
    • 2015-2016 Vermeer TR626
    • 2014-2016 Vermeer DT6
    • 2014-2016 Vermeer HG4000
    • 2014-2016 Vermeer HG6000
    • 2014-2016 Vermeer HG8000
    • 2014-2016 Vermeer TG5000
    • 2014-2016 Vermeer TG7000
    • 2014-2015 Vermeer TG9000
    • 2014-2016 Vermeer WC2300XL
    • 2015-2016 Vermeer WC2500XL
    • 2015-2017 Wabash National van trailers
    • 2015 Wilson CD-1080
    • 2015 Wilson DWH-550
     
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