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Vertical alignment mechanism on eccentric shaft

  1. Oct 26, 2015 #1
    What would be the appropriate mechanism such that when the eccentric circle is rotating about the larger center circle the table stays horizontal? The large circular is the driver (its continuously rotating)
     

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  2. jcsd
  3. Oct 26, 2015 #2

    BvU

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    You could check out some old drawings of how steam engines convert the to-and-fro of the cylinder to a rotating shaft with a flywheel...
    (Or how modern combustion engines do the same :smile: )
     
  4. Oct 26, 2015 #3

    JBA

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    Also do a web search on "scotch yoke"
     
  5. Oct 26, 2015 #4
    slot2.gif For this motion, is the rectangular prism necessary for the piston to go up and down? What would happen to the pistion motion if that part was removed?
     
  6. Oct 26, 2015 #5

    JBA

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    I need for to be a bit clearer about your question or what alternative assembly you are thinking about.

    If you rotate the assembly vertical with the table on the end of the rod and depend upon the table weight to return the pin to the bottom of the stroke then the bottom half of the yolk could be eliminated.
     
  7. Oct 26, 2015 #6
    Whats the bottom half of the yolk? Whats the yolk?

    Yes the flat table will rest on the end of that piston. My flywheel will be the driver, it will be rotating and that smaller white shaft will rotate about it (1/4" offset.) Im designing a vibrating platform that will move up 0.5" and down 0.5". The weight will be 150kg (table + box load)

    Thanks for your response
     
  8. Oct 26, 2015 #7

    JBA

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    What you call the rectangular prism in which the pin slides back and forth is generally known as the yoke.
     
  9. Oct 26, 2015 #8
    Right, so a slider(the yolk) will be necessary to keep the platform horizontal because without it, the piston can tilt.

    Is there any other method to keep the slot the eccentric cam rides in to stay horizontal?
     
  10. Oct 26, 2015 #9

    JBA

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    If you mean other than the vertical shaft, then making the yoke a rectangular plate with a horizontal slot for the pin and adding vertical rails to guide the side edges of the plate has also been used. Preferably, rollers that ride inside of slots in the guide rails are added to the top and bottom corners of the plate.
     
  11. Oct 26, 2015 #10

    JBA

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    wakadarc,
    I am going to be offline for a while; but I will check back in somewhat later today to see if you have any more questions.
     
  12. Oct 26, 2015 #11
    No problem.

    With the animation I posted, ideally I would like to keep that exact motion without having the rectangular prism (yolk). Guide rails requires precision and what not. Yes for the slot the eccentric shaft will ride in, there I will be using ball bearings.

    Thanks JBA
     
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