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scorpion2nz
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Joined: 27 Apr 2008
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Location: Hawkes Bay NZ
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 Posted: Sat Apr 07, 2012 8:02 pm Post subject: |
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thank you for your explanation and dissection. it looks like my theory was not to far off track but I have 1 question
when you rotate the piston on the conrod does it move up and down ?it will not be much but if my thoughts are right it will be noticeable
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kno3
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| Posted: Sat Apr 07, 2012 8:17 pm Post subject: |
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No, except for very little play in the ball end.
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wgreeley
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| Posted: Sat Apr 07, 2012 9:18 pm Post subject: |
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If the piston rod does not rotate and can move front to back because of the pin in the crank journal. And there are no rifling/cylinder guides.
What causes the piston to rotate 1/4 turn; allowing it to align with the steam or exhaust port?
Kno3
If you hold the crank stationary, can you get the piston to turn 1/4 by pulling the piston up and then return it to the original position by pushing the piston back down? |
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kno3
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| Posted: Sat Apr 07, 2012 9:58 pm Post subject: |
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No that doesn't work either.
I believe I have explained what makes the piston turn - it's a sort of pin device inside the piston, on the ball end. As the piston rod moves from side to side, it imparts rotational movement to the piston, via this pin or whatever it is.
It's just that I can't see without unsoldering the piston how it is exactly arranged.
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mogogear
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| Posted: Sat Apr 07, 2012 11:30 pm Post subject: |
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So a picture would be possible of the exposed piston?
And I read that you answered Dennis that the piston does not seem to extend up the rod as it rotates...or move upwards or down ..
but because I am an admitted skeptic...sorry - Did you measure this ?
So - with the piston turned one way - a total length of bottom of rod to top of piston is NOT different from the piston turned opposite way ?
Even by as little as 3mm? That could be all the lengthening we are looking for. And Archimedes drill type action is what I am suspecting as a rod - to-perpendicular gudgeon pin turns in tow inclined opposite slots in the inner piston wall.
Thanks for your indulgence of this question. My theory is getting in the way of me accepting your person observation- my apologies
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mogogear
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| Posted: Sat Apr 07, 2012 11:32 pm Post subject: |
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More doodles
I hope they are readable
Alas the subtle ghost shadows or internal dotted line of things unseen are not visible -sorry 
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Cowboy
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| Posted: Sun Apr 08, 2012 1:15 am Post subject: |
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| kno3 wrote: |
So there has to be some kind of pin inside the piston, on the ball end of the piston rod, which must slide in some shaped slot(s). What exact configuration it has still eludes me. |
I think I might understand it now. I just don't know how to explain it. Actually your explanation above is pretty good.
The piston can't move up and down on the shaft because of the ball end. But it can rotate. The rod ball has a pin through it, oriented in the same plane as the swing of the rod as the engine rotates. This pin fits in an angled slot in the piston. As the rod swings from side to side the piston is forced to rotate. At first thought it doesn't seem this would work, but when you consider that the end of the pin would change it's position relative to the top or bottom of the piston as the rod swings then it makes sense. Sort of. Well, almost. A variation of this same theme would have the pin fixed in the piston with the ball end of the rod slotted. |
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Roly Williams
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| Posted: Sun Apr 08, 2012 7:43 am Post subject: |
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| mogogear wrote: | More doodles
I hope they are readable
Alas the subtle ghost shadows or internal dotted line of things unseen are not visible -sorry |
I don't think that would work, Greg. The piston would just follow the rod up and down without rotating, just like any other engine, unless the friction in the vertical direction was much greater than the rotational friction; not likely. Also. it would not explain the ball.
I think the rotation must be caused by the sideways swing of the rod, not it's vertical motion. Cowboy's latest description sounds much more likely. That's more or less how I visualise it (given that my original understanding has been disproved).
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STEAMPROPULSION
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| Posted: Sun Apr 08, 2012 8:39 am Post subject: |
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Well done Calin.
I hope that soon some new explanations will appear, starting from what you have ascertained.
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Jean-Yves
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| Posted: Sun Apr 08, 2012 6:26 pm Post subject: Bowman Bryant valveless engine |
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I love the idea of a skewed crankpin though very difficult to build. But a skewed crankpin is not a must to rotate the piston. An other alternative (easier to build) is to put a pin in the liner guiding a groove with for instance a lozenge shape in the piston.
PS: I was following the discussion but I had lost my username and password. Just remember.
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mogogear
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| Posted: Sun Apr 08, 2012 6:37 pm Post subject: Re: Bowman Bryant valveless engine |
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| Jean-Yves wrote: | I love the idea of a skewed crankpin though very difficult to build. But a skewed crankpin is not a must to rotate the piston. An other alternative (easier to build) is to put a pin in the liner guiding a groove with for instance a lozenge shape in the piston.
PS: I was following the discussion but I had lost my username and password. Just remember. |
Jean-Yves-- good of you to join in and welcome back ! Can you draw what you describe to share?
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Jean-Yves
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| Posted: Sun Apr 08, 2012 7:27 pm Post subject: Re: Bowman Bryant valveless engine |
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| mogogear wrote: | ....
Jean-Yves-- good of you to join in and welcome back ! Can you draw what you describe to share? |
Here it is.
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Daryl Canada
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| Posted: Sun Apr 08, 2012 8:06 pm Post subject: |
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Is that a diamond shape (roughly) or square shape drawn in perspective? Would that not be a bit noisy and hard on the piston at TDC and BDC like a seriously worn bearing?
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MooseMan
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| Posted: Sun Apr 08, 2012 10:17 pm Post subject: |
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Wow, i'm late to the party! To all the good people who worry about me taking umbrage at stuff being taken from my website: never any need to worry about that, it's an honor. As for the BM engine.....once you see it working it all makes perfect sense. If anyone once a hi-rez scan of theBasil Harley source text, please drop me a pm.
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Jean-Yves
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| Posted: Mon Apr 09, 2012 6:21 am Post subject: |
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| Daryl Canada wrote: | | Is that a diamond shape (roughly) or square shape drawn in perspective? Would that not be a bit noisy and hard on the piston at TDC and BDC like a seriously worn bearing? |
It is a diamond. I know I'm bad in design. That is why I added a "developed piston" that is a cylindrical projection (as for the world maps) to show it is a diamond.
There groove must be inclined. Never horizontal (the piston movement being vertical). No major problem at TDC or BTC because there the speed is nil. Furthermore, the groove could be slightly longer (vertically) than the stroke. What matters is only the twisting movement of the piston. And I exagerated the width of the diamond. A rotation of the piston of something as 25° should suffice.
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