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BEAR
Administrator Joined: 07 September 2013 Location: Appalachian Mtn Status: Offline Points: 13734 |
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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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BEAR
Administrator Joined: 07 September 2013 Location: Appalachian Mtn Status: Offline Points: 13734 |
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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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d4570
.416 Rigby Joined: 27 January 2004 Location: United States Status: Offline Points: 9403 |
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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.
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Remember: Four boxes keep us free ,the soap box, the ballot box, the jury box, AND the cartridge box
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BEAR
Administrator Joined: 07 September 2013 Location: Appalachian Mtn Status: Offline Points: 13734 |
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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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d4570
.416 Rigby Joined: 27 January 2004 Location: United States Status: Offline Points: 9403 |
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In between deer hunts...
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Remember: Four boxes keep us free ,the soap box, the ballot box, the jury box, AND the cartridge box
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Irish Bird Dog
.416 Rigby Too many Joined: 01 March 2009 Location: Midwest Status: Offline Points: 5511 |
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d I see an "adjustment" tool of some kind lying in the bottom picture near the bottom....just what do you adjust with it?????????
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Irish Bird Dog
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RobertMT
.416 Rigby Joined: 12 March 2008 Location: United States Status: Offline Points: 4413 |
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If that won't push the boat, hook a generator up and power your block.
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Want to stop Drunk Drivers, from Killing Sober Drivers? Ban Sober Drivers from Driving. That's how Gun Control Works.
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d4570
.416 Rigby Joined: 27 January 2004 Location: United States Status: Offline Points: 9403 |
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Anything I NEED to!!!!!
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Remember: Four boxes keep us free ,the soap box, the ballot box, the jury box, AND the cartridge box
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d4570
.416 Rigby Joined: 27 January 2004 Location: United States Status: Offline Points: 9403 |
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I hope the tired 60 horses in the bug motor can turn it .
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Remember: Four boxes keep us free ,the soap box, the ballot box, the jury box, AND the cartridge box
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BEAR
Administrator Joined: 07 September 2013 Location: Appalachian Mtn Status: Offline Points: 13734 |
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three blade. that will keep the ground clearance decent.
support looks rugged. I'd double bolt and pin/all nuts...vibration!
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d4570
.416 Rigby Joined: 27 January 2004 Location: United States Status: Offline Points: 9403 |
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I did a no load, no prop today.
All looked good. The clutch started to move at around 1800rpm. I did not have my laser tack on the hub but it looked slower then the drive. It starts out at 3x1. As I increased the motor RPM the clutches both moved, as expected, the clutches Topped out at 3000 RPM, right where I was hoping. I should be like .70x1 there ,I would guess around the top end for the prop, 3100RPM. I didn't run it long but It was quiet and smooth and looked to be running true. |
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Remember: Four boxes keep us free ,the soap box, the ballot box, the jury box, AND the cartridge box
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BEAR
Administrator Joined: 07 September 2013 Location: Appalachian Mtn Status: Offline Points: 13734 |
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great. keep us involved in the project.
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d4570
.416 Rigby Joined: 27 January 2004 Location: United States Status: Offline Points: 9403 |
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Well.
I did some more welding to make the prop tower absolutely ridge. I did a dry running of the prop and drive at full power. Every thing looked true and I felt no vibrations or odd sounds. I did not run it long The clutch kicked in at 1500 rpm and at 3200 it Had moved to it's extreme extent. It is supposed to start at a 3 to 1 reduction then at full it should be at near 1 to 1. I was having a problem hand working the gas ,watching the motor tack, and the lazar tack on the prop. But it looked like at 3200 motor speed it was 3100 prop speed. I was using my wooden 64" 34 prop. It spun up to speed as fast at I could move the throttle. I'm hoping the 3 blade 54" will load the motor a lot more, Or I'll need more prop. Edited by d4570 - 01 February 2018 at 15:05 |
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Remember: Four boxes keep us free ,the soap box, the ballot box, the jury box, AND the cartridge box
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RobertMT
.416 Rigby Joined: 12 March 2008 Location: United States Status: Offline Points: 4413 |
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Looking good, did it blow the door off shop?
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Want to stop Drunk Drivers, from Killing Sober Drivers? Ban Sober Drivers from Driving. That's how Gun Control Works.
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Wing master
Administrator AKA StraightShooter Joined: 10 June 2003 Location: United States Status: Offline Points: 7481 |
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That's looking good D.
I was afraid that you would have a vibration from somewhere. Most Bugs I have seen the engines don't seem real smooth. I am looking forward to seeing a video of it going across the water. Wing master
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I have always considered myself to be quite the bullshitter, But ocasionally it is nice to sit back and listen to a true professional......So, Carry on.
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BEAR
Administrator Joined: 07 September 2013 Location: Appalachian Mtn Status: Offline Points: 13734 |
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great nothing like a full RPM test.
Close with that large blade, 3 blade model will give you nice clearance. I'm in the Florida keys/everglades......air boats everywhere. None as cool as the "BUG".
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d4570
.416 Rigby Joined: 27 January 2004 Location: United States Status: Offline Points: 9403 |
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Did you have to rub it in? Like 80* there and sunny right ? I can only run it at full rpm for a few seconds It blows everything in the shop around I'm afraid something will hook up with the prop and that would be a disaster. I'll try and pull it out in to the alley and try the 3 blade. Still no way to steer it yet. You gota go NORTH to see the catrermeran style airboats.
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Remember: Four boxes keep us free ,the soap box, the ballot box, the jury box, AND the cartridge box
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BEAR
Administrator Joined: 07 September 2013 Location: Appalachian Mtn Status: Offline Points: 13734 |
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Only 72 with 5-10 MPH wind. SUNNY. wish I'd have brought my snow goggles!
Fishing is for Baracuda, maybe some Tarpon later. renting a non-airboat. I really have never seen a cat airboat except in Montana. Must be Mt has all the craftsmen and boat designers.
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Wing master
Administrator AKA StraightShooter Joined: 10 June 2003 Location: United States Status: Offline Points: 7481 |
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Without a guard on your prop, be sure not to get your arms and legs tangled up in it. That wouldn't be good either.
Wing master
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I have always considered myself to be quite the bullshitter, But ocasionally it is nice to sit back and listen to a true professional......So, Carry on.
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d4570
.416 Rigby Joined: 27 January 2004 Location: United States Status: Offline Points: 9403 |
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It'll have a cage around it next thing after I get the gas tank installed and well before it's usable.
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Remember: Four boxes keep us free ,the soap box, the ballot box, the jury box, AND the cartridge box
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