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Old 10-21-2015, 04:28 PM   #9
Ski in NC
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City: Wilmington, NC
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
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Quote:
Originally Posted by Rustybarge View Post
Sounds like a complicated solution to a simple problem: vibration .

What's wrong with a counter weigh/damper on the crank/flywheel?
A two cylinder four stroke is an infernal machine. With two pistons moving together, firing is 360deg, but dynamic balance is HORRIBLE. Counterweights on the fw or crank can help, but they provide a rotating force, the piston force is linear along bore axis. Only way to cancel is to have a counter rotating balance shaft. Which these guys basically get with the two cranks.

Only thing with worse vibes is a single cyl, and not by much!!

Better balance can be had by a 180deg crank, with pistons moving opposite. But then firing order is 180deg/540deg which provides it's very own special flavor of shake at low rpm. Also sounds horrible. Sounds like a misfiring three cyl. And balance of the 180deg crank is better, but still sucks.

The Neander design looks like it has or nearly has perfect mechanical balance. Weights added to the CR cranks will act linear like the piston forces and should be able to nearly cancel.

I think also the low rpm shake from firing impulses is canceled too.

Maybe they could use this design for the snotty running four stroke two cyl gassers.

Only downside I see is cost. Low volume Euro stuff is expensive.
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