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Re: [multimachine] Mike, a big favor

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  • David G. LeVine
    ... Be sure to have guards on the chain, getting stuff caught can be bad, having chain chunks flying at high RPMs can make for an uncomfortable trip. Timing
    Message 1 of 9 , May 9 10:56 AM
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      On 05/08/2013 04:25 PM, HB wrote:
      > The jack shaft/sprocket system provides two purposes, first to be able
      > to achieve the required rotation for the propeller, and second to be
      > able to have the most efficient propeller and motor rotational speed
      > matching.

      Be sure to have guards on the chain, getting stuff caught can be bad,
      having chain chunks flying at high RPMs can make for an uncomfortable trip.

      Timing belts are better (they don't make as much noise, they don't
      require lube, etc.), but the sprockets are harder to get (although for
      1:1, 2:2 AND 1:2 ratios timing gears work well) and they have lower
      losses. Poly-v (aka multi-rib, etc.) are a really good choice (low
      losses, low cost, etc.), but need tensioners and the pulleys must be
      machined (with an MM, it is pretty easy.) Timing belts are used instead
      of timing chains to lower costs and improve efficiency, poly-v belts are
      used for the same reasons. Tensioners are not cheap, but prolong belt
      life, automotive belts should be fine up to about 7 HP, the narrow
      Toyota belts should be good to 3 HP. CV belts are good for 100+ HP with
      long life.

      Dave 8{)

      --

      "A word to the wise ain't necessary - it's the stupid ones that need the
      advice."

      Bill Cosby
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