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Harman XXV makes clunk/bang when feeding

Post in 'The Pellet Mill - Pellet and Multifuel Stoves' started by deltamind106, Jan 16, 2012.

  1. deltamind106

    deltamind106 New Member

    Joined:
    Jan 16, 2012
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    Loc:
    Gilmanton, NH
    I have a Harman XXV which I have put about 4 tons of pellets through over the last 2 years. Recently the stove stopped working in the middle of the night and a quick bit of troubleshooting the next morning revealed that the problem was that the auger was not turning at all. I removed the rear cover panel to have a look and the chain that links the auger motor to the auger itself had come completely off the gears. I removed all the pellets from the hopper and fed whatever pellets where left through the auger by manually turning the auger gear with my hand. The auger seemed to spin freely and the push plate seemed to engage without any restriction. So I put the chain back on and adjusted the tension and refilled the hopper with pellets.

    The stove ran perfectly for a few hours, but then started making this periodic clunk/bang sound. It would happen every few minutes. So I removed the rear cover panel again and sat there and watched the auger motor, chain, and push plate until it made the banging sound again. The bang occurs because the push plate appears to get "stuck" momentarily, which builds up a lot of pressure on the motor/chain, until the the push plate "unsticks" and all the pressure is released and the whole auger motor assembly goes "bang". Feeding then continues normally and silently for another few minutes until it does it again.

    What would cause this? The push plate "pushes" once per auger revolution when a cam type mechanism pushes on a fork that is attached to the push plate. Usually the push plate pushes without any binding, but every once in a while it seems to get stuck until enough pressure is built up and it releases all at once, producing a clunk/bang sound. The sound is loud and causes the whole stove to shudder-- it's definitely not normal.

    When I had cleaned out the hopper after the chain fell off, the auger spun freely and the push plate never got hung up. It was only after I refilled with pellets and ran the stove again that it started happening. And it ran for several hours before the problem started.

    I think something is out of place in the push plate, but I can't see in there. What do you think? How hard is it to remove the push plate mechanism?

    TIA for any advice!

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  2. summit

    summit Minister of Fire

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    1,903
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    central maine
    maybe a gummy feeder... you will have to pull the auger and find out... 1st make sure the fines cleanout is cleaned out!
  3. Don2222

    Don2222 Minister of Fire

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    7,307
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    Salem NH
    I had the exact same problem with the chain drive in a Harman Accentra 2. I found the chain was too close to the guard on the round tension pulley. When the stove heated up the chain expanded and got caught on the guard causing the banging! ! ! So I loosened the gear on the auger motor and pulled the gear out and tighened it down. Now the chain is not near that guard on the back side of the tensioner pulley. The stove is running fine now, problem resolved! :)

    See yellow arrow in pics of guard in back of chain on top of the tension pulley below:

    Click to enlarge:

    Attached Files:

  4. Murph

    Murph Proud Grandparent

    Joined:
    Dec 13, 2011
    Messages:
    79
    Loc:
    Cape Cod
    Had to replace the auger motor on a Accentra FS due to it being ripped apart. Then had a similar call only loud noise was the issue again found the motor was being pulled apart and when I powered the motor you could see it actually flex the mounting bracket. Called Harman and was told to take the rubber grommets off the mounting that they allowed too much movement and eventually through everything out of alignment.
  5. Don2222

    Don2222 Minister of Fire

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    There were no rubber grommets on this auger motor and it still made the clunking. Is there a way to pull the gear back on the auger?

    Did taking the grommets off fix your problem Murph?
  6. dhall28

    dhall28 Burning Hunk

    Joined:
    Mar 2, 2013
    Messages:
    182
    Loc:
    Central Ohio
    I've had the exact same thing before, i didn't take the bushings off though just snugged down the four bolts alot more than they were originally which took out all that extra play and aligned the two sprockets by moving the sprocket thats on the auger motor (the sprocket on auger shaft cant be used for alignment) and haven't heard back from the customer for several months.

    if you think its the slide plate hanging up its not that difficult to remove by opening up the fines box and lifting up the fork piece till the slide plate comes out. just look for any metal burs and give the whole plate some sanding with fine grit. you can also run the motor with the slide plate out to see if that make a difference. put the slide plate in and take a hammer and tap on the fork part that is inside the fine area, this will help set the pillow blocks that it rides on.
  7. Don2222

    Don2222 Minister of Fire

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    Hi
    It is still making the banging noise but sometimes it is loader than other times.
    I did watch it and saw the motor bracket flex and the chain ride up on the sprockets when the bang occurred. Also the slide plate was not engaged at the time. Adjusting the alignment of the two sprocket gears by loosening the auger motor gear and pulling it in or out seems to be the fix most of the time but not in all cases like mine. So for my case and others, Harman makes a chain drive upgrade kit (Approx $300) with deep tapered sprockes on the gears so the chain does not ride up and cause the banging. My Harman dealer friend said it does work much better.

    Here is the video I made but the banging was not very load at this time.
  8. dhall28

    dhall28 Burning Hunk

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    Loc:
    Central Ohio
    the whole kit (with sprockets, chain, hardware, tensioner, and bracket) is around $300 but if all you need is the chain and both sprockets you should be able to get those for around $100-125, chain 3-50-06667, sprocket 2-00-06626M, and sprocket 1-10-08550W.
    i've seen the gears excessively worn on one side before and the teeth slightly bent causing the chain to want to pop off even when the sprockets are very well aligned.
  9. Don2222

    Don2222 Minister of Fire

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    Thanks for the Info ! ! ! That's great!
  10. Don2222

    Don2222 Minister of Fire

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    Good news

    The new chain and sprockets fixed the problem! Thanks again!
  11. dhall28

    dhall28 Burning Hunk

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    good, they are fairly rugged system but they are more complicated than needed and can be tricky to troubleshoot. I'm glad that they went away from them and now do only the direct drive.
  12. Don2222

    Don2222 Minister of Fire

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    Thanks, I just picked up a 98 P61 in excellet shape for $1200. Is that a good deal. Same body as the new P61a stove. I can install an ignitor update kit. That is easy. Also a guy in Maine is sending me a slightly used 50lb hopper extension for $100.
    Is it a direct drive? I have not take the back off yet. LOL

    Attached Files:

  13. dhall28

    dhall28 Burning Hunk

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    well i can tell you a brand new p61a has an msrp of $3,589, but that doesn't include all the trims on that stove, all the trims/tile piece new would be an additional $352 and a new hopper extension is $219.
    the p series stove were never chain drive. they did the chain drive on the xxv, accentra, and advance only to try to make them thinner. with a p series this was never an issue so they were always direct drive.
  14. Lousyweather

    Lousyweather Guest

    looks like a chain rise toward the end of the video, about 3/4 of the way in (watch the Top part of the chain)...this would insicated to me, binding of some sort...possible gummy stove?
  15. Don2222

    Don2222 Minister of Fire

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    It looks that way, but this video was taken after the auger was removed and cleaned completely and a brand new Gleason-Avery motor installed. The banging I heard happened when the slide plate was not engaged. Therefore it had to be a bad chain and sprockets. Replacing them fixed the problem!
  16. Don2222

    Don2222 Minister of Fire

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    Thanks for the Info. I appreciate it.
    $3589.00 P61a
    +$352.00 Trim & Tile
    +$219.00 50lb Hopper Extension
    ------------
    $4160.00 Total

    I paid
    $1200.00 P61
    + 110.00 50lb Hopper extension $95.00 + $15.00 shipping
    +$375.00 Harman Ignitor Upgrade kit. - Hope to get that in. I have done one to another stove and I know it works very well!
    -----------
    $1685.00 Total for P61a upgraded P61

    $4160.00
    -$1685.00
    ---------------
    $2475.00

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