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Unread 01-12-2007, 01:27
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Re: Position idlers to get better chain wrap -- a question about good practices.

Quote:
Originally Posted by AdamHeard View Post
oh man.... dont have my book with me, but that much wrap on plastic rod seems like a lot of friction. No wonder.
Actually if they did it right there might not have been much friction at all. The trick is to install the rod in such a way as to make sure the chain is tight and then let it "wear in" a slot on the plastic rod. You migh want to pre-wear a groove in the rod to make sure the chain stays put, but it probably is not necessary. Once the tight chain wears into the rod a little bit it will go slightly slack. It will then cease to wear and the friction will be negligible.

Another approach is to not use tensioners at all. We have done this the past few years. In this case you need to be able to locate the sprocket axles precisely. You need to design the chain loop to have an integer number of links and preferably an even integer.

If there's interest I can do a white paper on how to do this.

Chris
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Christopher H Husmann, PE

"Who is John Galt?"