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Re: CVT

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  • Rob Rohde-Szudy
    Hey Kenneth, That Toro-like CVT system is pretty ingenous, and of course it s hardly a new idea. The only trick is getting it to actually WORK without flipping
    Message 1 of 4 , May 30, 2006
      Hey Kenneth,

      That Toro-like CVT system is pretty ingenous, and of course it's hardly a new idea. The only trick is getting it to actually WORK without flipping belts over and all kind of otehr weird things. I don't know, but I have a feeling the Toro engineers spent a lot of trial and error time getting it right. This is likely more than most want to do after building an entire boat. (Unless they're really poor bastards like me...)

      But you're not entirely wrong about it being possible to arrange for a reverse "gear" without moving the engine. One could use the V belts and tensioning idler just as you propose. But for reverse you'd have an idler WHEEL belted to the propr shaft. For reverse, it's mounting arm would rotate to contact a wheel on the motor's shaft. Just like Robb's system but moving two arms instead of the engine.

      On the other hand, I think it might actually be simpler to move the engine, since these aren't heavy motors we're talking about. Robb's Kubota is the heaviest I'd consider, and it's way lighter than the engine Atkin designed the hull for. I guess the only trouble is that all your engine connections have to be flexible, but I'm not sure that's all that much trouble.

      --Rob


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    • Kenneth Grome
      It is also possible to reverse the direction of rotation with a v-belt and four sheaves. My old Corvair car s fan was driven by a long V-belt that twisted 90
      Message 2 of 4 , May 31, 2006
        It is also possible to reverse the direction of rotation with a v-belt and four sheaves.

        My old Corvair car's fan was driven by a long V-belt that twisted 90 degrees on two "direction-changing" pulleys positioned in between the drive pulley and the fan pulley, thus changing the rotation from horizontal to vertical. If the belt stayed on the intermediate pulleys for an additional 90 degrees it would have resulted in a full 180 degree change in rotation.

        Kenneth Grome
        Bagacay Boatworks






        On Tue, 30 May 2006 09:06:07 -0700 (PDT), Rob Rohde-Szudy wrote:
        > Hey Kenneth,
        >
        > That Toro-like CVT system is pretty ingenous, and of course it's
        > hardly a new idea. The only trick is getting it to actually WORK
        > without flipping belts over and all kind of otehr weird things. I
        > don't know, but I have a feeling the Toro engineers spent a lot of
        > trial and error time getting it right. This is likely more than most
        > want to do after building an entire boat. (Unless they're really poor
        > bastards like me...)
        >
        > But you're not entirely wrong about it being possible to arrange
        > for a reverse "gear" without moving the engine. One could use the V
        > belts and tensioning idler just as you propose. But for reverse you'd
        > have an idler WHEEL belted to the propr shaft. For reverse, it's
        > mounting arm would rotate to contact a wheel on the motor's shaft.
        > Just like Robb's system but moving two arms instead of the engine.
        >
        > On the other hand, I think it might actually be simpler to move the
        > engine, since these aren't heavy motors we're talking about. Robb's
        > Kubota is the heaviest I'd consider, and it's way lighter than the
        > engine Atkin designed the hull for. I guess the only trouble is that
        > all your engine connections have to be flexible, but I'm not sure
        > that's all that much trouble.
        >
        > --Rob
        >
        >
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        > Yahoo! Messenger with Voice.
        >
        > [Non-text portions of this message have been removed]
        >
        >
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      • Rob Rohde-Szudy
        Hey Kenneth, True, but I don t think I d want to use up the space to do it that way. One of the advantages of Robb s system is that it is compact. Besides, I
        Message 3 of 4 , May 31, 2006
          Hey Kenneth,
          True, but I don't think I'd want to use up the space to do it that way. One of the advantages of Robb's system is that it is compact. Besides, I don't see how it's much harder to have a pivoting engine, since the motor mounts need to be relatively elastic anyhow.
          --Rob


          Message: 2
          Date: Wed May 31, 2006 12:58 am (PDT)
          From: "Kenneth Grome" bagacayboatworks@...
          Subject: Re: CVT


          It is also possible to reverse the direction of rotation with a v-belt and four sheaves.

          My old Corvair car's fan was driven by a long V-belt that twisted 90 degrees on two "direction-changing" pulleys positioned in between the drive pulley and the fan pulley, thus changing the rotation from horizontal to vertical. If the belt stayed on the intermediate pulleys for an additional 90 degrees it would have resulted in a full 180 degree change in rotation.

          Kenneth Grome
          Bagacay Boatworks



          ---------------------------------
          Yahoo! Messenger with Voice. Make PC-to-Phone Calls to the US (and 30+ countries) for 2¢/min or less.

          [Non-text portions of this message have been removed]
        • pinebaydude
          ... way. One of the advantages of Robb s system is that it is compact. Besides, I don t see how it s much harder to have a pivoting engine, since the motor
          Message 4 of 4 , Jun 1, 2006
            --- In AtkinBoats@yahoogroups.com, Rob Rohde-Szudy <robrohdeszudy@...>
            wrote:
            >
            > Hey Kenneth,
            > True, but I don't think I'd want to use up the space to do it that
            way. One of the advantages of Robb's system is that it is compact.
            Besides, I don't see how it's much harder to have a pivoting engine,
            since the motor mounts need to be relatively elastic anyhow.
            > --Rob
            >
            >
            >
            It occurs to me that one other way to do this, if you didn't want to
            move the engine up and down, would be to move the shaft up and down. A
            salvaged auto CV joint could be put on the shaft, then a simple frame
            could be welded up to support the tail shaft in pillow block bearings
            with a pivot point made concentric with the CV joint.

            Also:
            >Put a flat aluminum disc on the engine shaft, then put a rubber wheel
            on the
            prop shaft. Install the engine in the transverse position on a
            height-adjustable platform. By varying the engine height and speed so the
            rubber wheel contacts the aluminum disc at different distances from
            its center,
            you have a CVT system that provides the full range of speeds -- in
            both forward
            and reverse.
            >
            I made a drive like this for the feed on my bandsaw mill. It used a
            12v generator to spin a disc that drove a rubber tire on the cable
            feed drum. It was mounted on a sort of "tiller" handle and it gave me
            complete instantaneous feed control from full ahead to full return and
            anything in between. I'm not sure it would be the best for effecently
            driving a boat though, as it can involve a good bit of slipping and
            frictional losses.
            moT
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