Double acting Double Oscillator

Discussion in 'A Work In Progress' started by Brian Rupnow, May 24, 2018.

Help Support HMEM by donating using the link above.
  1. Jun 22, 2018 #121

    Brian Rupnow

    Brian Rupnow

    Brian Rupnow

    Well-Known Member Project of the Month Winner

    Joined:
    May 23, 2008
    Messages:
    10,420
    Likes Received:
    3,137
    Amvolk--a number of years ago I designed and built a " Steam Donkey Winch" I wanted a valve which would control the speed of the twin "steam engines" so I designed one that worked very well. If you follow the red line coming out of the boiler you will see the valve in place on the line. It worked very well, and gave great control over the engine speed. (And if those twin engines look a bit like a Cretors popcorn Engine" there is a very good reason for that.)
    [​IMG]
    [​IMG]

    [​IMG]
     
  2. Jul 7, 2018 #122

    Brian Rupnow

    Brian Rupnow

    Brian Rupnow

    Well-Known Member Project of the Month Winner

    Joined:
    May 23, 2008
    Messages:
    10,420
    Likes Received:
    3,137
    Today I was bored, so I decided to go back and address the subject of "running something" with my oscillating engine. I took 20 minutes to machine a pulley and added it to the crank arm on one side, then set up my "Crazy Joint" for a demo video.
     
    Anatol likes this.
  3. Jul 8, 2018 #123

    Anatol

    Anatol

    Anatol

    Well-Known Member

    Joined:
    Jan 22, 2018
    Messages:
    136
    Likes Received:
    15
    Gender:
    Male
    Location:
    Los Angeles
    that 'crazy joint' is special! :)
     
  4. Jul 8, 2018 #124

    Anatol

    Anatol

    Anatol

    Well-Known Member

    Joined:
    Jan 22, 2018
    Messages:
    136
    Likes Received:
    15
    Gender:
    Male
    Location:
    Los Angeles
    This is a quick general question about PTO solution. In the old days, they used big flat belts. Why wouldn't/couldn't you cut a V in the flywheel for a V belt? Is is just matter of gearing? Or aesthetics :)
     
  5. Jul 8, 2018 #125

    Brian Rupnow

    Brian Rupnow

    Brian Rupnow

    Well-Known Member Project of the Month Winner

    Joined:
    May 23, 2008
    Messages:
    10,420
    Likes Received:
    3,137
    O rings are cheap and easy to access. They don't need any fussy groove in the pulleys they run on, and they transmit power very well, and will also bend in many different planes if they are required to. They are stretchy, so you don't need any specially calculated centers between pulleys. Flat belts are not easy to access and require a certain amount of "fiddling" with to be sure that they track well and don't run off the pulleys. V belts are difficult to access in the size required for these small engines, and require a great deal more precision when machining the grooves in the pulleys.
     
  6. Jul 9, 2018 #126

    Brian Rupnow

    Brian Rupnow

    Brian Rupnow

    Well-Known Member Project of the Month Winner

    Joined:
    May 23, 2008
    Messages:
    10,420
    Likes Received:
    3,137
    If anybody would like to build that crazy joint, I have a complete set of drawings for sale for it. Contact me at brupnow@rogers.com
     
  7. Jul 9, 2018 #127

    Brian Rupnow

    Brian Rupnow

    Brian Rupnow

    Well-Known Member Project of the Month Winner

    Joined:
    May 23, 2008
    Messages:
    10,420
    Likes Received:
    3,137
    I've had a few questions about the "crazy joint". I modelled it in 3D, then animated it. It's kind of hard to get your head around it even when you see it in operation. And--whatever camera effect makes the stage coach wheels revolve backwards is still in play. I would have thought that would be overcome by now, but apparently it hasn't.----Brian
     
  8. Jul 10, 2018 #128

    JohnBDownunder

    JohnBDownunder

    JohnBDownunder

    Member

    Joined:
    Mar 1, 2012
    Messages:
    11
    Likes Received:
    2
    Great model and a fascinating action Brian. The action does not get any clearer (to me anyway) looking at this video of a real one in action here
    or here where I noticed an inset coloured pic of one. http://newsm.org/steam/almond-right-angle-drive/
    John B
     
  9. Jul 10, 2018 #129

    vederstein

    vederstein

    vederstein

    Must do dumb things....

    Joined:
    Feb 26, 2011
    Messages:
    480
    Likes Received:
    321
    It's a neat mechanism, but someone originally invented it and produced the mechanism. Which leads to a pertinent question:

    What's the advantages / disadvantages of this mechanism over bevel spur gears? The gears must have been better in some way since they are still used and this mechanism is part of the kinematic design scrap heap.

    ...Ved.
     
  10. Jul 10, 2018 #130

    Brian Rupnow

    Brian Rupnow

    Brian Rupnow

    Well-Known Member Project of the Month Winner

    Joined:
    May 23, 2008
    Messages:
    10,420
    Likes Received:
    3,137
    From what I discovered, there is a very small "dead spot" at two places on the rotation. That is why the flywheels have to be moderately heavy to get the mechanism over that flat spot and keep it turning smoothly.
     
  11. Jul 10, 2018 #131

    Ghosty

    Ghosty

    Ghosty

    Well-Known Member Project of the Month Winner

    Joined:
    Sep 21, 2016
    Messages:
    305
    Likes Received:
    279
    Looking at the video the input and output rotate in the same direction, gears would rotate in the reverse from in to out.

    Cheers
    Andrew
     
  12. Jul 11, 2018 #132

    Charles Lamont

    Charles Lamont

    Charles Lamont

    Well-Known Member

    Joined:
    Mar 24, 2011
    Messages:
    489
    Likes Received:
    127
    The mechanism might be easier to make if you have no way of milling gear teeth. It is likely to be quieter than straight-cut gears. On the other hand, it will be less efficient because of all the sliding bits. On the basis of judgment rather than analysis, I think it would be possible to balance the mechanism at least moderately well, but in most instances that will not have been done, so there would be vibration when running at much of a speed.

    I don't see any kinematic reason for a dead spot, but to avoid binding at some point I think it would need to be either exceptionally accurately made,
    or to incorporate enough slop to compensate.
     
  13. Jul 12, 2018 #133

    Brian Rupnow

    Brian Rupnow

    Brian Rupnow

    Well-Known Member Project of the Month Winner

    Joined:
    May 23, 2008
    Messages:
    10,420
    Likes Received:
    3,137
    A heads up to all of you who are currently building this engine from my plans. When I designed the pulley which fits over the crank arm, I put a set screw in it, but failed to realize that with the pulley in place there was no way to access the set screw in the crank arm. So, a clearance hole has been added to the pulley to allow access to the crank arm set screw.---Brian
    [​IMG]
     

Share This Page