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  1. #1
    Join Date
    Jun 2005
    Location
    St Petersburg, Florida
    Posts
    114
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    synchronous belt and sprocket conversion on air handler

    Recently I was tasked with helping on a weekend for a supposed sheave change that turned out to be a whole lot more. Being as the intended outcome is energy savings is why I post here.
    On an 18 year old 5) C V belt sheaves and belt drive with VFD drive. The sprockets supplied to us had no flange and no tensioners existed to retain the belt, and the motor carriage has only one bolt for adjustment with four cornered retainment bolts on the motor.
    Yippee. We had no laser and the system hasn't been accurately balanced in years and I couldn't get the belt not to walk off the sprocket. I failed and can not see this working without superb balancing and dead accurate alignment.
    The smart guys came Sunday with lasers and got it to stay somewhat. Monday they adjusted down to the 5/1000th according to the tech I helped and still it will not ride comfortably centered and not change in a few hours.
    Anyone else been doing these?

  2. #2
    Join Date
    Dec 2006
    Location
    Vancouver, B.C.
    Posts
    753
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    I doubt I would have any experience to input anything helpful but would like to see pictures if you got them.


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  3. #3
    Join Date
    Nov 2004
    Location
    up in the hizzy
    Posts
    3,389
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    A salesman from Trane showed up in our account and try to talk our customer to convert their AHU to synchronous belts promising all sort of energy savings, the AHU's already have VFD's and cogged belts, we told the client to challenge Trane to produce any evidence of savings and 3 local references, they did not hear from Trane again.
    There is not better place for the working men than the union! 100% UA the only HVAC union!

  4. #4
    Join Date
    Apr 2003
    Location
    St. Louis
    Posts
    1,269
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    Heres a link to abb just scroll down to literature HT500 drive system. Supposed to be 98% efficient. Something has to be moving like motor or blower bearings have excessive play. Base of the motor blower not stiff enough flexing. Never played with this drive system.

  5. #5
    Join Date
    Jun 2016
    Location
    Saavannah GA
    Posts
    12
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    Why would these sprockets run with no shoulders? to me that seems like just setting it up for failure. I realize alignment is critical, as is structural stiffness, but no shoulder just seems doomed to failure. I'm very curious to hear anything about this since this idea has been floated for my buildings since I have multiple units that need sheave replacement anyway and we are getting down to the small stuff in our energy program.

  6. #6
    Join Date
    Apr 2003
    Location
    St. Louis
    Posts
    1,269
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    Have you talked to the local rep or called the factory tech? Have you checked alignment with a string and with the belt under tension because theirs play in bearings.

  7. #7
    Join Date
    Feb 2016
    Location
    Louisburg Kansas
    Posts
    3,827
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    Did you check for a bent shaft?
    No man can be both ignorant and free.
    Thomas Jefferson

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