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converting rocking motion to rotary motion

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  • converting rocking motion to rotary motion

    Hi,

    I'm looking for a mechanism which will convert rocking motion (e.g. seesaw motion) to rotary motion (in one direction only), sort of the way old treadle sewing machine use to work. I recall there was a site that had all sort of motion conversion which was animated. Google hasn't be much helpful.

    The mechanism needs to be relatively compact.

    Thanks for your help.

  • #2
    I once played with a little engine that I saw on the web, it was called the green engine. here is a link to the web site. It might be what your looking for. http://www.greensteamengine.com/products.htm

    Mel
    _____________________________________________

    I would rather have tools that I never use, than not have a tool I need.

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    • #3
      I don't know if this will have the mechanism you envisage, but have a look here:

      http://www.flying-pig.co.uk/index.php

      It's a site that sells paper animation kits. Have a look at the tables at the bottom of the page,click on mechanisms, and then scroll through all the different animations and explanations.

      Peter

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      • #4
        Buy this book

        http://www.amazon.com/507-Mechanical.../dp/0486443604
        Non, je ne regrette rien.

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        • #5
          try looking here

          http://kmoddl.library.cornell.edu/collection-toc.php

          - Scott

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          • #6
            Is a book called, 507
            Mechanical Movements.
            May have something in it. Is available on ebay at the moment.

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            • #7
              Sounds like you're looking for a design the incorporates an escape mechanism such as used in clocks for every other wave motion.
              - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
              Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

              It is true, there is nothing free about freedom, don't be so quick to give it away.

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              • #8
                One way roller clutch.

                .
                .

                Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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                • #9
                  Too unspecific -- do you want continual rotary --- semi-intermittent? very intermittent (see SJ's reply)

                  Maybe this will help -- Got it along time ago from someone who posted it here -- pretty cool
                  http://www.mechanisms101.com/theo_jansen.shtml

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                  • #10
                    Automobile windshield wipers, only backwards. JIM
                    jim

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                    • #11
                      Didn't you describe the design of changing rocking motion to rotating motion with your description of a sewing machine treadle?
                      It's only ink and paper

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                      • #12
                        Basically the treddle is hooked to a crank pin on the input shaft. IIRC you have to spin the input shaft in the proper direction and from then on when you pump the treddle it will drive the shaft in the right direction. The link from the treddle to the crankpin is just one really long connecting rod
                        Forty plus years and I still have ten toes, ten fingers and both eyes. I must be doing something right.

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                        • #13
                          Thanks for all the replies.

                          Treadle mechanism would not be suitable because of the size and also depending on the position of the wheel, you need to get it started by spinning the wheel.

                          What's I'm trying to do is literally attach a generator to a seesaw (teeter-totter) so that when the children play, it will generate electricity and light up a string of Christmas lights. I want to have a flywheel on the generator shaft so that the lights stay on even if the rocking stops, and this necessitates that the generator spin in one direction.

                          I think one way roller clutch may the way to go. Your input would be appreciated.

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                          • #14
                            As John said.

                            This is how you make it. It can be a compact as you wish.

                            The shaft is tool steel. This one is cut to allow operation in either direction depending on where the HSS pins are installed. The gear is for illustration only as it happens to be the right size. Normally the clutch is fully enclosed with an outer roller housing that has some sort of bearings at each end. The depth of the slanted cuts and the size of the pins is calculated so that it just barely clears the ID of the outer housing by perhaps .001 or so. It is greased in operation and all parts must be hardened including the outer roller. This one is made of O6 tool steel for the shaft. The pins are drill bit shanks and the original outer shell (which I stole for something else) was hardened 1040 steel.







                            Here is one more to show the shape of the cuts.

                            Last edited by Evan; 03-23-2009, 12:09 PM.
                            Free software for calculating bolt circles and similar: Click Here

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                            • #15
                              It sounds like you want a sprag clutch, so you could buy or build. I used one in the winding arbor of a clock:


                              The pockets hold the little cylindrical pieces and the brass part fits inside the steel part. One or more of the cylinders will bind in the space between the parts when turned in one direction while none will bind when turned in the other direction. Saab used a similar design in their free wheeling mechanism in the '50s.

                              The simplest one way clutch is a spring, wound so it is a snug fit over a shaft with one end anchored to the output disk which mounts on the shaft via a bearing. When turned one way the friction tightens the spring onto the shaft and locks the output disk to the shaft. Turned the other way, friction expands the spring so it slips, unlocking them. More frictional losses than the scheme above but super simple. Used frequently in line printers.

                              John

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