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Trailer brakes not releasing

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

  1. suladas

    suladas Senior Member

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    Lost two tires on my trailer today, just dropped off track hoe everything was fine, not 5 blocks away and i'm getting pulled over cop behind me and watched my 2 tires blow out from brakes not releasing. I recently got the trailer, no idea on history, but 5 tires were in rough shape, 2 of the ones that blew, so pretty sure this was not the first time brakes had an issue.

    What could possibly be the issue? Only one side did it, and even getting it home after, the brake on that wheel never released, but the 5 or so times i've pulled it it's been fine. The shoes/drums are in pretty good shape. It was well above freezing here today so not just a frozen brake. The ABS light is also on.

    Trailer is a 2012 BWS 25 ton tag.
     
  2. DMiller

    DMiller Senior Member

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    Need to know Air, air/hyd or electric brakes?
     
  3. funwithfuel

    funwithfuel Senior Member

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    Forget to release the Johnny brake, maybe?
     
  4. hvy 1ton

    hvy 1ton Senior Member

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    I've had s-cams stick before. Gave the brake can side the tappy-tap-tap treatment and i tried not to use the brakes the whole way home. Took it all apart, replaced the slack adjusters and covered the s-cams and myself in anti-seize.
     
  5. Junkyard

    Junkyard Senior Member

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    Well.... there's a couple things it could be. Trash in the relay valve preventing release. Could be that a couple are far enough out of adjustment they'll roll. Could be an s-cam bushing has the cam hung up where it won't release. Could be broken springs on the shoes themselves. Plugged airline from relay valve to offending parking brake chamber (if so equipped).

    Simple process of elimination. If it has a fancy ABS relay valve they're kinda spendy. Make sure all the cams turn easy, no springs are missing on the shoes, no air lines plugged, chambers are good etc.

    If there's a restriction in the blue line where it won't exhaust properly it will cause them to drag. Might double check there isn't a gladhand shutoff or a quick connect somewhere plugged up.

    That's all assuming air which on a 25 ton I'd imagine that's what you have.
     
  6. 92U 3406

    92U 3406 Senior Member

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    I've seen the clevis pins seize to the slack adjuster too and cause dragging brakes.
     
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  7. Junkyard

    Junkyard Senior Member

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    Forgot about that one, yeppers that'll do it too. I've had to cut the darn clevis off before to get the offending slack adjuster out and we hardly see any salt or chemical down here.
     
  8. suladas

    suladas Senior Member

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    Sorry yes air brakes. The trailer also appears to have been sitting for awhile too, and quite a bit of dirt underneath. The truck I’m pulling it with is virtually new, was just rigged up to pull trailer on air recently. The brakes work good when loaded, and doesn’t pull one way or the other so not really far out of adjustment. Yes trailer has ABS.

    Trailer seems to have lots of air available to tilt deck and move ramps up/down if that makes a difference.
     
  9. DMiller

    DMiller Senior Member

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    I would start looking at clevis pins, anchor pins and s-cam bushings. Could have great shoes with thick blocks but drums could be too oversized, that will allow cam to reach a high point during a hard impact application as parking, any distortion as a flat spot on a cam head can do this too.
     
  10. suladas

    suladas Senior Member

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    Well after a lot (I mean a LOT) of swearing I finally got this thing disassembled. Like 8 trips to the city, first a 3/4" impact, then 1/2" hose, removing regulator and anything else I could think of to put out more air from my 20 gallon compressor, to getting fed up and buying a 60 gallon compressor, then buying the most powerful 1" impact they had because even with the bigger compressor the 3/4 impact wasn't doing it.

    Ending up spinning 2 nuts, I stopped as soon as they spun, hopefully I can get new ones in, the hub looks ok, and tearing the threads apart on one more. No idea how the lugs where so seized, put penetrating lube on them 3 days in a row and wire brushed them and the 1" impact rated at 2500 ft/lbs still struggled a lot to get them off, going to replace all studs and nuts though.

    Anyway I was able to cage the brakes and they released fine not sure if that eliminates the brake pod? (although I guess it wouldn't eliminate a possible air problem to it?) I attached pictures but both brakes shoes are worn much more on the backside which doesn't seem normal? Thankfully the drum is in good shape, going to replace the shoes though. There is some kind of metal piece broken by the s-cam though? I'm no expert but other then that and the shoes worn funny everything looks fine to me? There is no wobble in the s-cam, or would I need to remove shoes to verify that?
     

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  11. suladas

    suladas Senior Member

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    Forgot the most important one, of the s-cam.
     

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  12. crane operator

    crane operator Senior Member

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    All the dried up gunk on everything is a good indicator that the shaft is dried up and not turning free also. I would probably just get a set of rollers and springs when you get the pads, and clean up the shaft to get it turning. Drums really aren't that expensive and then you would have all new.
     
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  13. 92U 3406

    92U 3406 Senior Member

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    That metal piece is a retainer clip that holds the roller in.

    Not seeing any funny wear on the shoes though?
     
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  14. 63 caveman

    63 caveman Well-Known Member

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    suladas,
    Your stuff looks good to me. I think that the cam bushing are dry and chances are the slack adjusters are just as dry. I would pull it apart now clean and grease everything (including shoe anchor pins). without drums on you should be able to set park brake and then release it and shoes, slack adjuster, and camber push rod return on their own (just shoe return spring tension). I think that sitting has got things stiff.
     
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  15. Truck Shop

    Truck Shop Senior Member

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    Those s-cams are as dry as a pop-corn fart. Typical of equipment trailers.

    Truck Shop
     
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  16. DMiller

    DMiller Senior Member

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    Based on what I can see of the S-cam with the block thickness you have recently installed shoes (couple years anyway) minimal use but the pattern being so far up the back of the cam tells me the drums are oversize, A LOT. Measure or have them measured against max diameter. The above statement I agree with, cams have not been lubed in a long time, would not be surprised to see the zerks on the cam support bearings sheared and the bearings slipped. And that would be a yes as to releasing the brakes and seeing the cams roll back easy, quickly. One item of note, back the slack adjusters WAY off or the cam could over roll and drop rollers in on the backside of the S. Clean all that built up gunk off the rollers and cam heads, look for ground in flat spots on all of the parts.
     
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  17. DMiller

    DMiller Senior Member

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    Ought to note, while it is sitting wheels off, have someone or yourself release the brakes and see how fast each chamber releases.
     
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  18. Junkyard

    Junkyard Senior Member

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    Don't button anything up until it takes grease nice and easy. Also, when you replace zerks think about a comfortable angle when it's fully assembled. Not only zerk angle but orientation as well. That's mainly an issue on the cam bushing zerk in the backing plate.

    Clean clean clean. If there's a shadow of a doubt on drums go ahead and do them. Use the old ones for a vice mount or something. I use my old drums for shot-put practice. If I can't throw one at least 25' I need to eat more Wheaties. Shoe wear sure looks like drums are out to me or there's a mismatch somewhere.

    Do wheel seals while you're there. No sense in soaking a fresh set of shoes. Plus if they've drug odds are there not long for this world anyway. If slack adjusters won't take grease sometimes you can soak them and get the old crap pushed out where they'll take grease and function properly.

    Even when it was my dime I usually did a complete rebuild every other set of shoes. Chambers, drums, seals, bushings etc. On my lowboys they caught so much trash, my guys weren't great about greasing and I didn't want any inspection issues. A few hundred extra now is a lot easier than paying the scale master's cousin to cornhole you for a brake job at the scale or the side of the road. Pay me now or pay me later!!
     
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  19. suladas

    suladas Senior Member

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    Thanks guys, that helps a lot.

    I have a few questions. Should I be removing the s-cams and slack adjusters regardless, or clean everything, see if I can get it to take grease, then make sure they move freely and only remove if it they don't? How do I back the slack adjusters off being that they are auto slack adjusters? I never looked but is there still that nut to turn them like the manual ones? I don't know if it makes a difference, but picture was taken with caging bolt turned all the way in.

    The drum has very little wear not where i'd say it needs to be replaced, there is a tiny ridge where the shoe ends, but not much and there is tons of thickness left, I attached a picture but don't think it will show much. I have receipt from old owner showing mid 2014 all new drums and shoes done, and last time trailer was inspected. The shoes didn't even seem that worn, just the very back of both pads, the rest had lots of life left. I measured diameter of drum and it is smaller then the max diameter. I don't know how to verify if it's the correct drum though? They are 17.5" wheels and drum says 12.25x7.5". The one thing I did notice is the receipt from old owner shows drum price at double what I was just quoted when I picked up the shoes, they quoted the drum off of me just bringing in old shoes, not seeing old drum so maybe it is a different drum? Speaking of that I attached a picture of the studs, the parts guy said they are wrong and used for aluminum wheels (mine has steel), they look funny to me because they are so long, which is why I think I had such a problem getting the lugs off because there is so much thread to get full of junk and ruin the threads. However, all 6 wheels have all the same studs so I doubt on a 2012 trailer someone would have already replaced every single stud? Considering I was told $1000 to replace all studs and nuts.

    The oil was dirty, but every wheel is full to right level, and hub turns nice, no sign of oil on shoes at all. Should I also be pulling the bearings to actually check? I was worried about having to re-torque that nut as I don't know if my torque wrench goes that high. Wheel seals would mean pulling the bearings as there's a inner and outer correct?

    I want a safe trailer that won't give me problems getting pulled over, but at the same time I might put 2,000 miles on it a year, so if I can get by with the drums i'd prefer that, instead of spending another $1000 on them. I bought new pads and hardware kits for all wheels though.

    Sorry if some of my questions are dumb, it's been about 7 years since i've done air brakes, only only ever done them once so not very familiar with the setup.
     

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  20. Junkyard

    Junkyard Senior Member

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    Snap a pic of your slack adjusters. They'll have a hex head into the side or a small rod with a clevis pin running length wise with to adjuster. If it's the hex head on the side just unscrew it and you can back it off. They make a tool to save the time of unscrewing it but it's not necessary. If they're not completely froze inside from muck and hard grease you can back them off without releasing anything, it'll take some effort and pop as you back off. Another option is to un-pin from chamber and run them on around the direction of adjustment until they're where you want them for assembly. Setting pre-load on spindle nuts isn't that hard, it doesn't take a tremendous amount of torque. Some guys torque, some use a dial to measure endplay and some just do it by feel.

    Yes if you do seals the inner and outer bearing will come out. Is there any mention of seals etc when it was worked on last. You might be lucky and just need to clean things up and grease it thoroughly. I wouldn't mess with studs, being too long doesn't hurt anything. Just anti-seize them throughly when you go back together. Also, apply some to the hub where it centers the wheel, it'll make things easier to get apart. Hub pilot wheels like to grow onto the hub!

    If you don't use it much I'd just assemble clean after verifying everything works and takes grease. You can't really over grease the brake system so don't be afraid to hit it every couple times you pull it. Especially if your roads are crap, it'll help push trash out of the cam bushing and slack adjuster. Also, any pins need anti-seize as well as the spines where the adjuster goes on the s-cam. Can't use too much of that either.
     
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