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Trailer brakes not releasing

Discussion in 'Trailers' started by suladas, Dec 13, 2017.

  1. heymccall

    heymccall Senior Member

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    My two cents worth...
    On my tagalong trailer brakes, my number one issue with dragging brakes is the inner camshaft bushing. Looking much like a tennis ball, it is held in place by a left and right cover plate. Corrosion effectively squeezes that bushing until no amount of grease can allow smooth action. That includes rust scale inside the covers, and the bore of the axle bracket.
    Anytime I have doubts, I fully assemble the camshaft without shoes in place, and ensure that I can 360° rotate the cam EASILY.
     
  2. suladas

    suladas Well-Known Member

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    S-cams and bushing are brand new a month and 200 miles ago. That’s why I’m so stumped on what it could be.
     
  3. heymccall

    heymccall Senior Member

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    Again, that inner bushing has been the source of 80% of my brake dragging problems. Call the tennis ball bushing to have, let's say, a 2" OD. The axle bracket on all of mine had, say, a 1.95" ID after years of rust. I had to open up that bracket bore, to, say, 2.05" before the bushing didn't deform when installed. And, the bushing cover plates HAD to be replaced.
     
  4. heymccall

    heymccall Senior Member

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    Since you're still dragging, disconnect the slack adjuster clevis pin and cycle the camshaft with a pipe wrench. Smooth and fluid with a pipe wrench it should be.
     
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  5. funwithfuel

    funwithfuel Senior Member

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    Ok, let's go back. When you took your trailer to the shop, they replaced a single spring brake chamber correct? When the center seal fails on a spring brake it can be a real PITA to find. They are inconsistant. Sometimes they fail hard and always leak. Here's the problem, they don't leak where you can hear them. It slowly or lightly applies air to the service side. That's why your stroke was good and even. Did you purchase new spring brakes as part of your brake job? Did you just get foundation brakes replaced. If I were you I would not worry one bit about my bearings. If your seals weren't leaking when they went in there to replace the brake chamber you should be just fine. Unless that hub got so hot that it blistered the paint off of the surfaces I would not be worried one bit.
    Something else about your statement kind of caught me. You said you only use it 3 maybe 4 times a year. That is a long time for oxidation to occur and grab ahold of the S cams also does push rods in the brake chamber are steel the housing of the brake chambers aluminum corrosion is going to occur there as well. If nothing else just hook up to it once a month and exercise the brakes just to break loose any corrosion. Honestly if I were the Tech helping you I would have just put on a brake chamber and left it at that.
     
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  6. DMiller

    DMiller Senior Member

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    Get the wheels/hubs(ALL) off the trailer, remove the brakes, make certain ALL the rotating mechanisms are free and roll/swing easy. Apply air to the parking side of the chambers with the service side line disconnected, should be NO Air issuing, connect everything back then release the park system operate the service air(Wheels/hubs still off), the Quick Release valves HAVE to dump immediately and if don't will hold air on the service brakes where the one with closer adjustment or weaker return springs will drag.
     
  7. suladas

    suladas Well-Known Member

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    They did not replace any brake chambers. They replaced s-cams, shoes, s-cam bushings, bearings, and seals. It didn't take any paint off, but like 4 hours later the wheel/hub was still hot enough to pretty much melt snow on contact, i'm no expert but in my opinion I believe that had to have negative effect on the bearings. Apparently they just blew out the brake chamber, and that was the only problem. Claiming everything else is fine and wasn't damaged. We'll see I guess. I used the trailer 3-4 times in the month since it was fixed. It sits for maybe 2 weeks tops at a time, usually used once a week though.
     
  8. RZucker

    RZucker Senior Member

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    Bingo... "truck was recently rigged to pull a trailer on air"... Has this shop tested your trailer with YOUR truck? I have seen so many hack jobs when straight trucks were converted to pull trailers by people that thought they knew what they were doing. A 1 or 2 psi leak to the blue line is all it takes to drag a brake.
     
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  9. Junkyard

    Junkyard Senior Member

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    Or a restriction that won't let blue line exhaust properly.....
     
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  10. RZucker

    RZucker Senior Member

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    Like Bugs in a TP valve?
     
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  11. Junkyard

    Junkyard Senior Member

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    Sure could be. Or if it was a converted truck does it even have one? If it does has it been plumbed properly. The recently rigged part makes me wonder which dash valve setup is has. Lots of options for air supply or restriction issues.
     
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  12. suladas

    suladas Well-Known Member

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    Same shop who worked on trailer did the rig up, so either way, their problem, especially considering I paid them $2k to do the rig up, and yea it's a hack job for sure. The truck was in the shop at the same time as trailer was getting brakes done, so they had every opportunity to make sure everything worked together good.
     
  13. suladas

    suladas Well-Known Member

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    The truck had dash button from factory, and as far as I know most lines were there, just needed to be ran to the back.
     
  14. RZucker

    RZucker Senior Member

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    2k? and the money you have spent on the trailer too? Yeah they better be figuring it out for free now. Had a guy bring me a 48' flatbed 2 weeks ago, said the brakes dragged. I checked the trailer with my regulator bank and it all worked perfectly. He hooked up to it and it was dragging again... sticky brake pedal... not enough to crack the relay valve on the tractor but enough to drag the trailer. Sometimes it doesn't take much. Just saying the guys you picked might not be the right ones.
     
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  15. DMiller

    DMiller Senior Member

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    ALL trucks with air brakes have the Yellow park control, did they add a trailer red control, a tractor protection (TP) valve and or a hand control under the wheel?, lines for trailers are NOT necessarily installed on straight trucks OEM. If not they spliced into the system and it is not legally nor properly set up.
     
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  16. suladas

    suladas Well-Known Member

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    Yes $2k just for the trailer part rig up, then $6k for the repairs, then another $1.5k for 6 new tires. It's been fine since, well that part anyway.

    On monday when I tieing down my track hoe I happened to look at the brake through the hole in the deck, the clevis pin on the slacker adjuster about to fall out because the pin is gone. Thankfully I seen that. Can't believe it, that was the brake that was just dragging, the frigging shop JUST looked at that brake for not being done properly the first time.

    And another joy, a week before that when i'm stopping at a light I hit a bump go to take off from light, trailer brakes won't release. After much swearing and climbing under trailer, fitting to one of the air tanks on trailer broke off. Not placing too much blame on the shop for that, but I find it hard to believe that fitting just went like that, especially being behind the air tank. I'm guessing it was partly broken for awhile.

    Hopefully that is it, because I am really getting sick of this trailer. Can't really blame it, just the shop that is completely useless.
     
  17. suladas

    suladas Well-Known Member

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    The hand control for trailer brakes was there from factory as well as red button, and they hooked it up so it does work.
     
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  18. RZucker

    RZucker Senior Member

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    Ok... You already had the "tractor kit" on the truck and they charged 2K to run 2 air lines and install a pair of gladhands? Or did that include a hitch and plate too? Just trying to figure out how to make easy money here. (Kidding).
    I think you really need to find a shop with a balance of quality and price. I would shoot one of my guys that forgot that cotter pin, I don't mess around when it comes to brakes mainly because I don't want to be a co-defendant if a customers truck runs over a busload of kids, Nuns, and puppies.
    On the broken valve... I'm betting it's been leaking for awhile and they never put air to it to check. Had a customer bring a 40'-24' flatbed combo in last week, said the brakes dragged. The diaphragm on his hitch for the pull trailer was leaking just enough air to drop the supply pressure to the pull and drag the maxi brakes slightly. Tough leak to find.
     
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  19. Truck Shop

    Truck Shop Senior Member

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    I haven't read this whole thread but I am suspecting the brake chambers. Either an internal leak from emergency side to service side inside of air chamber or broken springs on
    park brake side and service side or the rod from air chamber to slack adjuster rubbing on air chamber where the stem passes through it. With the red trailer dash valve pushed in
    and trailer brakes released how long does it take for air pressure to drop from 120 psi to 90 psi? Install a gauge on the blue line coming from trailer by removing the blue glad hand
    and see if you have and feed back air in that line.
     
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  20. DMiller

    DMiller Senior Member

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    There is also the plight of us older Mechanics, Cannot hear the slight air leaks above the din of the tinnitus. I really have to struggle and push effort to find where air is leaking anymore, cannot always soapy water where you need to.
     
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