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BEAR View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BEAR Quote  Post ReplyReply Direct Link To This Post Posted: 13 October 2017 at 14:36
The primary sheave is centrifugally operated and engages the trans-mission belt when the engine speed reaches approximately 2700 rpm.When the engine is rotating at idle speed or below 2700 rpm, the trans-mission belt rides on a ball bearing between the halves of the primarysheave assembly (see Fig

As the engine speed increases, centrifugal effect forces a garterspring in the end cap outward against the contour of the end cap and axially against the movable sheave half. The profile of the end cap causes the engagement.  As the sheaves are broughttogether the transmission belt is forced outward to ride on a larger diameter of the primary sheave assembly, increasing belt speed (seeFigure 3-8). Since the belt length remains constant, the secondarysheave halves spread apart, allowing the belt to ride on a smaller diameter (low gear).  As the belt climbs between the cone pulley assembly the gear ratio decreases (high gear).


If the torque rating is increase above the rated torque,  the movable sheave will rotate at a speed slower than the outer primary sheave (input speed).  this will causes the garterspring to move at this slip rate, and wear against the wear  disk and/or the  end cap.

The assembly also includes a wear disk.  Which I assume is to compensate for undesred wear, but is very limited.  The wear would be preferred to be on the softer wear plate than the garterspring or the end cap.

If you know the HP of the VW and its top rpm, along with the HP of the snowmachine and it's top speed the max torque of each is easily calculated.
D,  you always have the most interesting  and thought provoking issues.  BEAR 





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Post Options Post Options   Thanks (0) Thanks(0)   Quote BEAR Quote  Post ReplyReply Direct Link To This Post Posted: 13 October 2017 at 14:50
If this helps your thinking.

60 hp @ 3000 rpm means max torque output of VW engine is   105 Ft lbs.

The Snowmachine   40 hp engine, if it was made to run at say 5000 rpm (just a guess for a 2 stroke)  would have a shaft max output torque of  42 ft pounds.

These are MAX calculations.   Only a test will tell.

Where is the extra chain drive transmission you installed?  between the vw engine and the SM clutch?  between the SM clutch and the prop?

Remember the VW engine will only put out enough torque to match the prop load. 

 Propeller loads increase with the square of the speed.  So if you double the speed of the prop...you need 4 times the torque.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote d4570 Quote  Post ReplyReply Direct Link To This Post Posted: 13 October 2017 at 18:21
The chain is after the clutches. To the prop. I can change it easily if needed
Right now it is 1 to 1.
The clutch starts at 3 to 1 and finishes at .70 to 1, a little over drive...
The prop is made to run at 3100 rpm and with max pitch takes 55 hp to turn it at that speed according to the prop people.
THATS the reason for the torque converter. 
Normally a 1600cc can't get it turning that fast because there max hp is at 3000 rpm, that is with out a reduction , but then you need to run your motor at 4000rpm + to get to the max on the prop..
 It's like chasing your tail.
Remember: Four boxes keep us free ,the soap box, the ballot box, the jury box, AND the cartridge box
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BEAR Quote  Post ReplyReply Direct Link To This Post Posted: 14 October 2017 at 08:51
The prop required torque to reach 3100 rpm would, if my slide rule is still working, be    93.5 foot pounds of torque.  
   
Sounds to me you are very close, on the torque ratings.  your CV, Continuous Variable transmission, is centrifugally controlled, sort of an automatic.  And I suspect the bell housing curve is profiled for the snowmachine thread load and a 2 stroke.  So you might not get to top speed the fastest, BUT it should take you there.

Still looking like a sound project D.

We are anxious for the test results on run up.
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