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Author Topic: My Invention  (Read 106747 times)

TinselKoala

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Re: My Invention
« Reply #75 on: August 20, 2012, 11:33:46 PM »
@johnny: some research terms for you:

Moment
Arm
Moment arm
Torque

You might also like to take a look at a book called "Statics and Dynamics: Vector mechanics for engineers" by Beer and Johnston (get a used copy if you can find one) and their "supersite" here:

http://www.mhhe.com/engcs/engmech/beerjohnston/

You do have some calculus under your belt, I hope.

keep building, cheers....
--TK

zoelra

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Re: My Invention
« Reply #76 on: August 20, 2012, 11:53:58 PM »
Sorry, I posted before finishing my thoughts.  This build will assume the bob has already been trapped by the cord and will test the falling of the counter weight and lifting of the bob.  I plan on testing different pulley positions, bob heights, and counter/bob weights to see if I can find the right combination.  The way the two weights are interconnected with the cord, this looks to be a basic 1:1 pulley setup.  As the counter weight falls, the bob is lifted.
 
I hope to complete a few tests this evening.

johnny874

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Re: My Invention
« Reply #77 on: August 21, 2012, 01:48:59 AM »
  Rick,
 with something like this, modifying things shouldn't be to difficult.
 It may be lifting at a 2:1 ratio might work.
 One thing I thought of is that when the pendulum swings outward, it landing on a ramp might help. It would be some what of a trade off.
 It would lose some force because the ramp would be pushing it further out. But as long as it has more force than the counter weight, then that's okay. It could be that it would take a two step process.

zoelra

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Re: My Invention
« Reply #78 on: August 21, 2012, 03:57:24 PM »
James,
 
The first test I wanted to do was a 1:1 setup to see if the 2.5lb counter weight would lift the 2.5lb bob.  One end of the cord is fixed to the center of the counter weight and the other end to the center of the bob.  Well there was no lift with this setup.  In fact the bob actually pulled down slightly raising the counter weight.  However, when I added some weight to the counter weight, the reset action ocurred as you predicted.  I need to take the mechanism off the wall and drill new holes to get the setup close to your specs.  I also need to adjust the pulley mechanisms as the cord kept getting caught between the bearings and the side washers.  See my second post for a short video of this first test.
 

zoelra

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Re: My Invention
« Reply #79 on: August 21, 2012, 04:15:47 PM »
The video is too large to attach.  I will work on reducing the size.

zoelra

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Re: My Invention
« Reply #80 on: August 21, 2012, 04:59:15 PM »
Ok, here is the video.
The first part of the video is with the weights being even.  You can see the mechanism drops slightly on the bob side.  When weight is added to the counter weight, that side becomes heavier and the mechanism moves to reset the bob.

johnny874

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Re: My Invention
« Reply #81 on: August 21, 2012, 06:36:33 PM »
Ok, here is the video.
The first part of the video is with the weights being even.  You can see the mechanism drops slightly on the bob side.  When weight is added to the counter weight, that side becomes heavier and the mechanism moves to reset the bob.

  Rick,
 There is something I have thought of. Can you try running the line from the pulley on the left to directly to the swinging weight.
 It won't lift it As high, but it would pull it in the direction it is swinging. And this would be with  one to one weight.
 
                                                                                                                                                   Jim
 
edited to dd; it should lift the swinging weight close to a 45 degree angle.

zoelra

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Re: My Invention
« Reply #82 on: August 21, 2012, 07:05:17 PM »
I know the angle of the pendulum shaft is not at 45 degrees, but is the cord run correctly?
 
Also, I'm sure you had a chance to view the video, with a little extra weight on the counter weight side, the reset works.  I have to go back and read my original post to you, but I may have misspoke about the weight and distance relationships.  My early tests used a 5lb weight for the counter weight and a 2.5lb weight for the bob.  I dropped the pendulum from a level position.  At the bottom of the pendulum swing, the down force was
 
5lb (CF of 2X weight of bob) + 2.5lb (weight of bob) = 7.5lb
 
This lifted the counter weight of 5lb.
 
What I am getting at here is if the counter weight weighs more than the bob, the reset looks like it could work in this scenario.  I guess moving the cord attach position from the center of the counter weight to a position closer to the main lever pivot point would also increase the force, but it would also reduce the distance traveled.  A future test will show this.
 
Anyway, your reset approach is looking good !!!!

zoelra

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Re: My Invention
« Reply #83 on: August 21, 2012, 07:07:49 PM »
I need to make a YouTube account so I can post so longer running videos.

johnny874

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Re: My Invention
« Reply #84 on: August 21, 2012, 07:34:51 PM »
  Rick,
 You might be pleasantly surprised. By pulling the pendulum with the pulley over tbe counter weight, it could move the pendulum further.
 I do like your set up. I'm kind of surprised someone hasn't thought of a test set up like yours before now.

   Jim

edited to add; yep, I've seen your video. I think I'm going to build something like you have to do some tests with.

zoelra

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Re: My Invention
« Reply #85 on: August 21, 2012, 08:30:49 PM »
I see what you are saying about the force being less because of the angle.  In one of my ealier posts, I suggested a higher drop position because the force would be less near the top (also because of the angle).  Same idea as your suggestion, except the weight would have to be "pushed up" rather than "pulled up".  I like higher drop points because I want greater CF at the bottom of the swing, hopefully to do more work.
 
Mounting on a wall does have it's advantages.
 

johnny874

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Re: My Invention
« Reply #86 on: August 21, 2012, 09:25:58 PM »
I see what you are saying about the force being less because of the angle.  In one of my ealier posts, I suggested a higher drop position because the force would be less near the top (also because of the angle).  Same idea as your suggestion, except the weight would have to be "pushed up" rather than "pulled up".  I like higher drop points because I want greater CF at the bottom of the swing, hopefully to do more work.
 
Mounting on a wall does have it's advantages.

  Once you get to know me, you'll find sometimes I can just enjoy doing the math. I am hoping this weekend to build a test fixture.
 One thing about lift is once the angle goes over 45 degrees, the amount of work is greater than the cf it would generate. An example of this is a 1 lb. weight could lift a 2 lb. weight to 45 degrees. And if 2 one lb. weights are used, it should lift the pendulum a little higher.
 That's when they ( a 2 lb. and a 1 lb. weight) would be in equilibrium. And if you look at the shift in balance, going with 45 degrees, if the bob is 10 in. from it's fulcrum, it would shift 14 inches.
 How they translates into useable force, not really sure. But what is known is that once the weight is beneath it's fulcrum, it would have shifted 7 inches. That would mean the counter weight could possibly be in closer about 3 1/2 inches.
 What I like about your set up is that it can probably give a good idea if it's worth pursuing. I think it can test most of the parameters to see if the potential for maintaining a single oscillation pendulum is possible.
 
edited to add; @All, i have asked Stefan to change the name of this thread to single oscillation pendulum.

johnny874

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Re: My Invention
« Reply #87 on: August 22, 2012, 12:09:54 AM »
  one thing I figured out is a 10 lb. weight would have about 12 ounces of cf if it swung from a height of about 12 inches.
 If the pendulum is 12 incnes long, a 30 swing equals 6 inches. If the pendulum is 18 inches from center, it lessens the force of the weight by about 1/3rd. This is where tbe most potential might be able to be realized.

johnny874

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Re: My Invention
« Reply #88 on: August 22, 2012, 02:24:21 PM »
  zoelra,
 to try for a perpetual pendulum, what needs to be known is how much motion it loses swinging from one side to the other and back again. then the question would be when the cross beam tilts to the cw side, can it lift the pendulum sufficiently to compensate for it's entropy.
 if the pendulum is pulled up from a 45 degree angle, the hoist can probably be over driven with a 1.5:1 ratio.
 the pendulum can be caught at it's inner most swing limiting how much the cross beam would need to tilt.
 will be relaxing so I'll be ready to go this weekend.
 of course, some would say God gave this to me because it's what I need when what I wanted was a family.
 
edited to add, zoelra, here is a video of a weight swinging with little resistance. as one person mentioned, can't tell angles without calculus. wish I would have known that sooner.
 
 
http://www.youtube.com/watch?v=iFS1so_sccI&feature=youtu.be
 
edited to add; maybe tinselkoala can do some calculus to mark the swing from one side to the next and back again to find it's entropy. as he said, it's over my head. And if you pull the pendulum's weight from an angle of 45 degrees, it can move the weight 1 1/2 times more than the cw while the cw weighs half as much. I'm sure somewhere they can say a book says that but it would have to be in other terms like w=md, but then, how is that in literal mechanical motion or application ?
 love it when someone links all sorts of material but is vague as to what it says and where it says it. means they didn't read the book they're quoting, only heard of it.
         any way, do need to take a break. my medical situation is my life. it's better than trying to work around idiots who are to lazy to consider something. seems then it's more of a control issue. you know, someone is doing something and they aren't the lead dog. then again, I thought that was why Stefan started this forum, so people would have a place to discuss idea's that might not be main stream.
« Last Edit: August 22, 2012, 03:40:27 PM by johnny874 »

zoelra

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Re: My Invention
« Reply #89 on: August 22, 2012, 04:18:51 PM »
The attached video shows the results of running the cord along a 45 degree path to the pendulum bob.  The counter weight raises instead of falling which says there are other forces in play.  My guess is this is due to a portion of the weight of the bob still being applied to the pendulum shaft and then the mail lever.