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Old 07-18-2010, 03:08 AM
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rickoff rickoff is offline
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The Swinging Gym - model for an effective gravity wheel?

I initially made reference to this device in the F.M. Chalkalis thread in the following three posts:

F.M.Chalkalis gravity system a donation!

F.M.Chalkalis gravity system a donation!

F.M.Chalkalis gravity system a donation!

I see that David (Matos de Matos) has started a thread (Magnetic pumping gravity assisted wheel) to explore the possibility of magnetically simulating weight shifting movements in a gravity wheel design, and I think that's fine, but the apparatus and movements shown in that thread do not at all follow the stated objective of building "a prototype of a mechanical mimic of a Swinging Gym.” David's ideas and methods may prove to be useful, however I thought that I would start this separate thread for those who find the elements of the Swinging Gym particularly interesting, and who would like to explore the possibility of building a device modeled after the actual design parameters of the Swinging Gym.

The Swinging Gym, for want of a better description, is basically a large scale human powered gravity mill. Having personally participated in successfully rotating this device at a rate of more than 1 revolution per second, I can attest to the fact that this gravity mill really works, and that it develops tremendous power. For those not already familiar with the Swinging Gym, here is a video of some inexperienced users making a go of it.
YouTube - Dennis Barber Swinging Gyms Hanbury Steam Rally Stoke Prior Fair 19th September 2009
The object, of course, is to swing the cage back and forth until it finally goes "over the top," and continues rotating. It can easily sap all your strength to reach the top, even if you understand how to get it there (which the fellows in the video obviously don't), but once over the top it takes relatively little effort to keep the rotation going, and not much more than that to accelerate it.

As you can see, the human occupant, or occupants, enter a cage at ground level that is suspended in such a way as to always keep the cage in a vertical position, and this is unlike any other gravity wheel design I have seen, where routinely the suspended item or items either swing freely or become inverted at some point in the rotation. I believe this is one key factor that makes rotation with the Swinging Gym possible. Another factor is the positioning of the six suspension arms and counterweights. This becomes evident in the two photos shown below. The first photo shows the Swinging Gym about half way between the bottom and the top of a cycle, while the second shows the unit closer to the ground.

http://q6k4yq.blu.livefilestore.com/...231.jpg?psid=1

http://public.blu.livefilestore.com/...232.jpg?psid=1

Upon examining the two photos, one can see that each side of the cage is suspended from 3 pivot points (one at the top of the support frame, and two further down, to form a triangle pattern. The two lower support arms are attached one at the front, and one at the rear, of the cage side at the bottom. The upper support arm is attached to the centerline of the cage side somewhere near shoulder height of the occupants (depending on their actual height of course), and I believe this height of attachment is also a factor that contributes to success. The final contributing factor of the build is the positioning and weight values of the six diamond-shaped counterweights seen at the ends of the support arms. Without the counterweights, it would probably be impossible to ever get over the top and rotate. Now of course there must be a"perfect" setting to counter the weight of the cage and its occupants that would allow for best performance, so in a scaled build of this device it would be best to allow a method of sliding the counterweights and locking them in place. I can attest to the fact that I had much better luck operating the device when I was 13 years of age than when I was in my early 30's, even though at the later date I was far more stronger and had more weight for weight shifting purposes. Because of my additional 35 pounds or so, the stationary counterweights were inadequate in weight. It should be noted that the full amount of the counterweights is less than the weight of the cage alone, and that, for this reason, the cage will always seek ground level if left alone. Therefore, there is an initial imbalance, which becomes an even more pronounced imbalance when weight is added to the cage. The imbalance factor is important to retain to some extent, as it enhances the inertial thrust at the rotational arc perimeter.

A human can rotate this device, either alone or with a companion, through use of cleverly and properly timed weight shifting within the cage, so the question becomes whether or not the correct and necessary human weight shifting movements can be simulated by other means that would allow for continuus rotation. Such other means might include mechanical, magnetic, electromagnetic, hydraulic, gravity, or inertial actuated means, or a combination of these, or possibly other, methods. If anyone reading this has the opportunity to use one of these Swinging Gyms, and to take video of one rotating successfully this summer at an amusement park or carnival, please do so and post links here so that we can study the required weight shifting movements in detail. I can tell you that the trick is to always maintain a position within the cage that is closely adjacent to to the outer perimeter of the rotating arc, as this develops the greatest inertial thrust both going down and going up. The operator's position within the cage must begin to shift from one side to the other close to the top, and again near the bottom, of the rotation, in order to keep weight distribution close to the arc perimeter. Also, the operator needs to bend their knees to keep their weight low as they near the bottom, and then extend the body mass to a full height while going up. You can see that either side of the cage has bars that the operator can hold onto. If going down, you are holding the bar at one side, and if going up you are holding the bar on the opposite side. When shifting weight from one side to the other, you hold onto the side you are on with one hand as you step to the middle and reach out to grasp the opposite handlebar. At this point, which should be within 10 degrees or so of the top or bottom of a cycle, you should be holding both bars, and should then continue deliberately leaning and moving quickly to the side you are aiming for. In your arms and hands, it feels like you are actually "pulling" the cage lower as you approach the bottom, and then "lifting" it higher, as you begin to move upward. This cannot be so, of course, but it does give you the feeling that this is what you are doing when you move correctly. And believe me, even when you know the right way to move, this activity can quickly leave you feeling totally exhausted, and will greatly increase your heart rate. My second trial, in my early thirties, left me feeling like I was going to have a heart attack. I was in great physical shape at that time, and a non-smoker. I gave it all I had, which was a bit too much, and had to lie down for about an hour afterwards to recuperate. So let that be a warning. You are much better off to take along a strong young teenage boy of about 100 to 120 pounds, to whom you have thoroughly explained how to achieve rotation, and to videotape his attempt, than to try this out yourself if you are over thirty years of age, over 150 pounds of weight, or not in great physical shape. It is hard to find these machines nowadays, because many states outlawed them after some serious accidents occurred. These were caused by inexperienced users who failed to keep a firm hand hold, and who lost their balance and were buffeted around inside the cage. One can fall against the cage side or bottom with enough force to receive a serious concussion if balance is lost and a firm grasp is not maintained by at least one hand at all times.

Let me know if any of you are interested in building a scaled down replica that could be used as a test prototype. If so, the first step would be to approximate the measurements of the full size version shown in the video, so as to show the scaling dimensions of the build parameters in diagrams. The next step would be to produce an animated demonstration showing the unit in rotation, and then to show the movements that are required by a human operator to achieve rotation. All of this must be defined clearly before anyone can start thinking about possible methods of achieving continuous rotation through other than human powered methods.

I'm already stretched quite thin between my Pipe Dream project and summer rehab projects at my home and cottage (the summer season is short here in Maine), but will attempt to answer any questions, and help to steer others in the right direction. I will also help to approximate dimensions using my own recollections, as well as the video and still pictures, and will try to give a basic starting reference for that in my next post.

Best to all, Rick

Last edited by rickoff : 07-24-2010 at 04:51 AM. Reason: sp
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Old 07-18-2010, 07:21 AM
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Here's an original advertisement for a mobile swinging gym setup of the type that is most commonly found at traveling carnivals that go from town to town during the summer.



These are of a somewhat smaller scale than some stationary units found at amusement parks, since they must be built to clear bridge underpasses on highways. The first time I tried one, at age 13, was at an amusement park in New Jersey some 52 years ago. We estimated that the top of the cage was 30 feet above ground at its highest point in the rotation, and the ride operator said our estimate was just about right. The units in the above photo are constructed a bit differently than the ones shown in the video of my previous post, but the triangular support framework and triangular pattern of the pivot points is closely related. The main difference in this suspension is that the upper pivot arm is connected to the top center of the cage side, rather than at shoulder height as shown in the video, and I believe that makes rotation more difficult, although it adds more stability to the suspension. This photo does show more clearly, however, the actual connections of the pivot arms to the cage. It also shows two important human weight shifting attributes.
1. In the cage closest to the viewer there are two boys. Both should be in the position maintained by the boy on the right side of the cage. The cage is moving downward, and will soon be at the bottom of the arc. The boy at the right side is bending his knees to shift his weight lower in the cage while "pulling" on the bar at the right side as the cage moves down, and is just beginning to reach for the handle bar at the other side of the cage. Ideally, he should have his body weight lowest at bottom dead center (BDC), and be holding both bars at that point, but also leaning more to the left and moving quickly in that direction, and should begin to extend his body as the cage passes BDC and moves upwards, very much like the boy who is already at the left side. These boys are actually working aginst each other. Now look at the fellow in the highest cage. He is centered in the cage, at a full standing height, and with both bars being held. If he is already rotating, then he appears to be rotating counter-clockwise, and is about to make his move to the left side of the cage. This move should begin somewhere around 30 degrees from the top, and the final lurch to the left should occur at about 10 degrees. While going down, it is most advantageous to keep the body as close to the cage side as possible, but to also begin turning the body so that you will be able to step towards the other side near the bottom.

Now if we reasonably estimate the cage height at 7 feet from top to bottom, then the cage scales to about 7ft x 3.5ft x 2ft, approximately. The pivot arms are each about 8 ft in overall length, including the counterweights, and are about 5 ft between their pivot points. The supporting triangular framework is about 11 ft high from its base to the uppermost pivot point, and perhaps 5 to 6 ft wide at the base. The base is slightly obscured in the photo, but the width of the trailer is stated as 7ft 10 inches, and this would be measured at the widest part, where the wheels and fenders protrude. The cage would be suspended so that the bottom of the cage would be close to the ground or base level, perhaps just 6 inches above. So, if the distance between pivot points on the pivot arms is about 5 ft, then the lower pivot points on the triangular frame are about 5 ft + 6 inches, above the base. These are just rough guesstimates, of course, but not very far from actual measurements, so gives a reference to draw up some construction diagrams of the parts, which can then be scaled down to a manageable experimental build. A frame height of perhaps 2 to 3 ft from base to upper pivot point would be quite adequate for experimental purposes, and at 2.2 ft would represent a 1/5 scale model.
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Old 07-18-2010, 08:12 AM
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Here's another still photo that shows a different, but more stable setup. Notice the bars extending from the framework to the ground, where they are likely anchored well. You could rightly say that this is an improved version. Stability is important where you have an out of balance condition. As you can see, three cages are reaching the top nearly in unison. If all four were doing this then the combined thrust could lift the base off the ground if not anchored down sufficiently. The pivot arms appear to be longer on these units than in the previous post's photo, perhaps around 9.5 ft overall length, which would place the counterweights where they would relieve more of the human burden, and that's why these people seem to be doing so well. The designer probably assumed that by making the ride easier, more people would choose to go on it, and to also go on repeat rides, and that makes sense. The green and blue cages are rotating counter-clockwise. The person in the blue cage has just cleared top dead center (TDC), while the woman in the green cage is about 15 degrees or so past TDC, starting to bend knees, and preparing to turn her body so that she will be facing towards the opposite direction near the bottom of the rotation. The fellow in the yellow cage is standing in the wrong place unless he is rotating clockwise and is in the process of making his move from the left side of the cage to the right side as he goes over the top.


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Old 07-18-2010, 02:52 PM
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I can tell you that the trick is to always maintain a position within the cage that is closely adjacent to to the outer perimeter of the rotating arc, as this develops the greatest inertial thrust both going down and going up. The operator's position within the cage must begin to shift from one side to the other close to the top, and again near the bottom, of the rotation, in order to keep weight distribution close to the arc perimeter. Also, the operator needs to bend their knees to keep their weight low as they near the bottom, and then extend the body mass to a full height while going up. You can see that either side of the cage has bars that the operator can hold onto. If going down, you are holding the bar at one side, and if going up you are holding the bar on the opposite side. When shifting weight from one side to the other, you hold onto the side you are on with one hand as you step to the middle and reach out to grasp the opposite handlebar. At this point, which should be within 10 degrees or so of the top or bottom of a cycle, you should be holding both bars, and should then continue deliberately leaning and moving quickly to the side you are aiming for. In your arms and hands, it feels like you are actually "pulling" the cage lower as you approach the bottom, and then "lifting" it higher, as you begin to move upward. This cannot be so, of course, but it does give you the feeling that this is what you are doing when you move correctly.

Best to all, Rick
Hi Rick:
Your experience is for sure, more trustful than my mental exercise of riding a machine that I never saw.
I see the swinging gym pumping mechanism similar to pumping a swing.
In the swinging gym, ideally, would be that the counter weights where the same mass of the cage and with same arm length.
That would give equilibrium at 90º, with fulcrum in the midpoint between the cage and counter weight, horizontally.
We have to pull the cage to the vertical position, to get in, but the system will be more efficient, and with little effort you can pump your own weight up, like pumping a swing.
It is like a lever, that when you move closer to the fulcrum, you go up, if you had a balancing counter weight on the other extreme.
The clips at this page, Pumping of a Swing - Physics | Grinnell Collegeshows that, as you shorten the path on the way up, reducing the time where kinetic changes to potential energy, and reducing the work of gravity, some kinetic energy is left over to pump the swing.
Did you see my last thread where I am using rotating Halbach permanent cylinders as weights and as pumping mechanisms?
Mechanical Parametric Oscillator
It may be a perpetual machine of the third kind.

David
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Old 07-18-2010, 06:33 PM
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Hi Rick:
Your experience is for sure, more trustful than my mental exercise of riding a machine that I never saw. I see the swinging gym pumping mechanism similar to pumping a swing. In the swinging gym, ideally, would be that the counter weights where the same mass of the cage and with same arm length. That would give equilibrium at 90º, with fulcrum in the midpoint between the cage and counter weight, horizontally. We have to pull the cage to the vertical position, to get in, but the system will be more efficient, and with little effort you can pump your own weight up, like pumping a swing.
True, it would require less exertion if you start out with a fully balanced system, where the counterweights balance out the weight of the cage and its occupant, when the occupant is positioned at the center of the cage. This may well be the situation where we would like to begin testing at, since it will allow for the least exertive forces possible. On the other hand, closely balancing the system will greatly reduce the inertial momentum, which is a very important factor in attaining and maintaining rotation with this device. Remember that, in your swing example, there is no counterweight. You have the full weight of the suspended swing and rider providing inertial thrust. Now suppose that instead of hanging that swing from rope or chain, that it was suspended from rigid bar stock. You would still have the same swinging pendulum effect. But what if you extended the bars an equal distance above the pivot point and placed a weight there equal to the swing rider's weight? The system would then be balanced, and should be ideal according to your reasoning. In actuality, though, this removes all inertial thrust except the slight amount that can be gained by the rider through body positioning, and it is quite unlikely that the rider could gain a high arc position, let alone go over the top and rotate.

As shown in my previous post, extending the counterweights of the Swinging Gym does make it easier in that it requires less exertion from the rider. So there definitely is a positioning of the counterweights that would prove ideal for the load of the cage and its contents. That ideal will not be a balanced load, though. Instead, it will be an unbalanced situation that provides for strong inertial thrust, but which does not require exhaustive exertion by the rider. For the Swinging Gym, this imbalance is designed to be always greater than the rider's weight, but it certainly could be optimized for whatever the rider's weight might be. An optimized imbalance, with rider aboard, might be somewhere in the neighborhood of, let's say, 100 pounds. If set up this way, the rider would find operation relatively easy, but it would still allow for good inertial thrust. I'm certain that, set up this way, I could rotate the machine with relative ease for an extended period of time, and that mimicking the required weight shifting movements by other than human means would be quite possible.

I hope you can find one of these Swinging Gyms this summer and try it out for yourself, and then this will all be much clearer. What state are you located in? In the northeast US there are numerous town and county fairs where traveling carnivals make the rounds, and where you would most likely find one of these machines.

Best 2 U David,

Rick
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Old 07-18-2010, 08:25 PM
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Remember that, in your swing example, there is no counterweight. You have the full weight of the suspended swing and rider providing inertial thrust. Now suppose that instead of hanging that swing from rope or chain, that it was suspended from rigid bar stock. You would still have the same swinging pendulum effect. But what if you extended the bars an equal distance above the pivot point and placed a weight there equal to the swing rider's weight? The system would then be balanced, and should be ideal according to your reasoning. In actuality, though, this removes all inertial thrust except the slight amount that can be gained by the rider through body positioning, and it is quite unlikely that the rider could gain a high arc position, let alone go over the top and rotate.

I hope you can find one of these Swinging Gyms this summer and try it out for yourself, and then this will all be much clearer. What state are you located in? In the northeast US there are numerous town and county fairs where traveling carnivals make the rounds, and where you would most likely find one of these machines.

Best 2 U David,

Rick
Hi Rick:
My apologies but I have to disagree with you.
A robot battery powered child in a fixed rod will rotate 360º and accelerate at each swing with amplitude less than 360º and after each revolution if exactly mimic as showed on the picture.
The sketch below shows that any unbalanced gain will be used on the other side going up.
I am not aware of other mechanical pumping of oscillators other than direct push or the change of center of mass shortening the up trajectory of the bob.
The design of the unbalanced swinging gym, with such a heavy cage, in my opinion is to difficult the rider and make him work.
Remember how easy is pumping a swing?
I live in Luanda, Angola, the most expensive city in world. Typical African capital of an oil reach country.
We import bottled water and vegetables.
I couldn´t find anywhere in the Country simple permanent magnets. I order and import them.
That is the reason of not presenting physical prototypes, I just can´t make them.
Well, everybody is invited to prototype them

David


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Old 07-19-2010, 07:26 AM
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Hi Rick:
My apologies but I have to disagree with you.
A robot battery powered child in a fixed rod will rotate 360º and accelerate at each swing with amplitude less than 360º and after each revolution if exactly mimic as showed on the picture.
The sketch below shows that any unbalanced gain will be used on the other side going up.
I am not aware of other mechanical pumping of oscillators other than direct push or the change of center of mass shortening the up trajectory of the bob.
The design of the unbalanced swinging gym, with such a heavy cage, in my opinion is to difficult the rider and make him work.
Remember how easy is pumping a swing?
Okay, you can disagree with me, but about what, exactly, are you disagreeing with? And what is this "robot battery powered child in a fixed rod?" I have absolutely no idea what you are talking about, David, as I simply can't visualize that.

So are you saying that a swinging gym would be optimized for performance if the total of the counterweights equaled the weight of the cage plus the rider? If so, then it looks like we will simply have to agree to disagree and leave it at that. Yes, I have pumped many a swing in my younger years, and remember that quite well. And yes, it is relatively easy to pump a swing, but that's because you have inertia working for you both when swinging downward and swinging upward through the arc. Remember, a swing is unbalanced - there is no counterweight above the pivot point. As I said in my last post, if you suspended the swing from rigid metal rods that were extended an equal distance past the pivot point, and fastened counterweights there to equal the total weight at the bottom of the swing (including the rider), then you would have an almost impossible time trying to pump the swing. Don't believe that? Well then, try it and let's see.

Exactly balancing out the Swinging Gym would prove just as futile. You really do need a good amount of inertial thrust to swing, and rotate the device. Yes, the standard Swinging Gym is purposely engineered so that it is not that easy to get over the top, Some are easier than others, as my last post with photo shows. The counterweights are extended further out on that build, which relieves some of the operator burden, and they could certainly be extended even further out. At some point of extension you would find the ideal setting to allow for operator ease while also leaving enough imbalance to provide good inertial thrust. In my last post, I suggested that perhaps a 100 pound imbalance might be ideal. That would be much less imbalance than a standard Swinging Gym setup, but should still allow for adequate inertia. The extension would have to be made adjustable, of course, to provide the same 100 pound imbalance for varying cage loads (riders of different weights, and multiple riders).

Too bad you don't live where you could try out a Swinging Gym, but you could certainly build a full scale one almost entirely from junked parts. And a small one, with a 2 to 3 foot high frame could also be quite useful for experiments, even though it won't allow you the experience of riding it over the top.

Best regards to all,

Rick

Last edited by rickoff : 07-19-2010 at 07:39 AM.
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Old 07-19-2010, 11:43 AM
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So are you saying that a swinging gym would be optimized for performance if the total of the counterweights equaled the weight of the cage plus the rider?

Best regards to all,

Rick
Hi Rick

I didn’t say “plus the rider”.
What I am trying to say is that doesn’t matter how many counter weights you add to a pendulum, gravity will always look for the equilibrium, and that any gain on the descend will be used on ascending.
To pump a pendulum, with amplitudes less than 180º or over (full rotation) you have to change the center of mass. (or give it a push)
The energy gain when pumping is proportional to the mass moved around.
Anywhere you add mass to unbalance the system, it will only change the equilibrium position and increase the mass to be pumped, with your little mass moving up and down.
The picture shows the battery operated robot that bends the knees on the bottom and rises then on the top.
I would like to see one of those. And will accelerate for sure.
David
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Old 07-19-2010, 11:47 AM
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[quote=Matos de Matos;104476]The picture shows the battery operated robot that bends the knees on the bottom and rises then on the top.
[quote]

It is the other way around:
The picture shows the battery operated robot that raises the legs on the bottom and bends the knees on the top.
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Old 07-20-2010, 08:26 AM
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The picture shows the battery operated robot that bends the knees on the bottom and rises then on the top.
Hi David,

I'm well aware of the attributes and functional parameters of a pendulum, so no need to cover that again. I'm glad to hear that you would not suggest counterbalancing the full weight of the cage plus the rider, and so it seems you would agree that a useful Swinging Gym type of device does need at least some amount of imbalance. By useful, of course, I mean a device capable of doing work, such as pumping water or generating electricity. A fully balanced sytem would not be a useful device. True, just one gram of imbalance added to the top of a balanced system could theoretically cause the unit to rotate downwards, but the developed torque would be insufficient to accomplish any useful work. To do that we need an appropriate weight of imbalance working for us, and that's why I suggested perhaps allowing for a 100 pound imbalance after taking into account the weight of the cage plus the weight of the rider. This would make operation of the device quite easy, but would allow for plenty of useful torque development as well. Would you not agree?

Rick

p.s. - What is it that the large circle at the bottom of your last post is supposed to represent? Also, why does the the robot have knees bent at the top and the right side, as well as the bottom of the circle? Then too, why is the circle skewed on the left side to show a solid and a dotted curve?

This isn't meant to represent a robot mimicking the human movements used with a Swinging Gym, is it? If it is then it is way off.
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Old 07-20-2010, 10:24 AM
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Hi David,

p.s. - What is it that the large circle at the bottom of your last post is supposed to represent? Also, why does the the robot have knees bent at the top and the right side, as well as the bottom of the circle? Then too, why is the circle skewed on the left side to show a solid and a dotted curve?

This isn't meant to represent a robot mimicking the human movements used with a Swinging Gym, is it? If it is then it is way off.
Hi Rick:

Did you look at the clips on this page?
It is very elucidative, specially the first, where he shows how to pump a pendulum pulling the weight inwards on ascending.

Pumping of a Swing - Physics | Grinnell College

On the picture posted earlier, the swing before the circle shows the mechanism to pump a swing, where the child, when it reaches the bottom, stands up and when reaches the end of the amplitude (stop) he lays down bending the knees. This is done both ways.

If you hang the child from a solid rod, and you drop him from the top, with the knees bend, and if he does stand up at bottom, he will pump the swing on ascending, accelerating.
On top he will have a higher velocity than when he was dropped, a full rotation can be accomplished, and on the next rotation, if he pumps again he will have higher velocity.
At each revolution he will accelerate, accelerate to a maximum allowed by his physical forces.
This is what I am trying to show with the circle picture.
The left dotted line is the trajectory of a normal pendulum, and the solid trajectory, is when the child pumps it, changing his center of mass, closer to the center (fulcrum).

This is the only way I know to pump a pendulum, or an unbalanced wheel that is a pendulum with amplitudes of 180º, (reaching the top), or over 180º, with a full revolution.

David
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Old 07-21-2010, 06:49 AM
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rickoff rickoff is offline
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Originally Posted by Matos de Matos View Post
Hi Rick:

Did you look at the clips on this page?
It is very elucidative, specially the first, where he shows how to pump a pendulum pulling the weight inwards on ascending.

Pumping of a Swing - Physics | Grinnell College
Sorry, I am at my cottage in a remote area of Maine for several days, and only have slow dial-up service here, so cannot view any clips. I can most assuredly tell you, however, that if you keep to the inward side of the Swinging Gym cage as it is ascending from the bottom, you will not make it over the top. The outward side of the cage, as it comes down, becomes the inward side going up, so it would be very easy to just stay on that side if it would work, but it doesn't. I have fully explained the body movements and timing that is necessary for successful operation, and suggest that you review those. You can show me diagrams and video clips until the cows come home, but it doesn't matter. When it comes to the Swinging Gym, which is the subject of this thread, I have the experience to know what works and what doesn't. I suggest that you draw a diagram of a Swinging Gym apparatus, and then show (inside the cage) where you think a human operator should be positioned every 30 degrees for best performance. This thread is about mimicking the successful operator of a Swinging Gym, not a swing, so let's start with the correct apparatus. You could use the attached simple image, or make your own. The attachment simply and roughly depicts twelve 30 degree positions, and does not mean to suggest that 12 cages should be suspended within one device. Let's assume that the operator is rotating the device clockwise.



Rick
Attached Images
File Type: jpg Swinging Gym at 30 degree increments.jpg (22.3 KB, 11 views)
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Old 07-21-2010, 07:25 AM
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If we were to treat the swinging gym as a parametric oscillator, could the operator simple stand up at the bottom and squat 45° later to add energy to the system?


And if we treat a pendulum as at driven oscillator, could we not simply attach a cross bar to the end and rotate it horizontal at one end of the swing action and then vertical at the other? That is, perpendicular and then parallel to the pendulum arm?

What if we used some magnets to flip that cross bar between horizontal and vertical? Could this be the secret to splitting the conservative field into non-conservative parts?

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Old 07-21-2010, 10:29 AM
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When it comes to the Swinging Gym, which is the subject of this thread, I have the experience to know what works and what doesn't. I suggest that you draw a diagram of a Swinging Gym apparatus, and then show (inside the cage) where you think a human operator should be positioned every 30 degrees for best performance. This thread is about mimicking the successful operator of a Swinging Gym, not a swing, so let's start with the correct apparatus. You could use the attached simple image, or make your own. The attachment simply and roughly depicts twelve 30 degree positions, and does not mean to suggest that 12 cages should be suspended within one device. Let's assume that the operator is rotating the device clockwise.

Rick
Hi Rick:

Sorry to come up with the swing, I thought that was the same mechanism, where the applied forces where done at same points, but in fact the change of center of mass is different, and very interesting and shall be analyzed with more time.
This is how I see it.
On the right side the body has to move down faster than the cage being in the outer (biggest radius) and when reaches the bottom has to raise the body and keep it as close to the center as possible.
It will be easier to push down the weight on the right side faster than the cage, than in the swing where you have to pull it up at the highest point.
The driven mechanism is the next issue, and if you do not mind I can post some opinions. Unfortunately, Africa my home, doesn’t let me do prototypes.

Sorry Rick, but I have to answer the off topic subject bring by Harvey.
I am trying to open a discussion on the parametric oscillator and did open a few threads with different ideas, but unfortunately, people are not responding, and what they see is if works or not and the “thinker” mathematical and academic status.
I am not seem any “Ifs”
I know that some proposals are “physically” impossible, but they are only ideas that when talked and though about will lead to better ones.
Please check the treads that I have where instead of a bar I have a sliding magnet.
Thank you
David
Physics Quest
Mechanical Parametric Oscillator
Magnetic pumping gravity assisted wheel
Pendulum hydro pump and double pendulum hammer
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Old 07-22-2010, 06:08 AM
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Originally Posted by Matos de Matos View Post
Hi Rick:

Sorry to come up with the swing, I thought that was the same mechanism, where the applied forces where done at same points, but in fact the change of center of mass is different, and very interesting and shall be analyzed with more time.
This is how I see it.
On the right side the body has to move down faster than the cage being in the outer (biggest radius) and when reaches the bottom has to raise the body and keep it as close to the center as possible.
It will be easier to push down the weight on the right side faster than the cage, than in the swing where you have to pull it up at the highest point.
The driven mechanism is the next issue, and if you do not mind I can post some opinions. Unfortunately, Africa my home, doesn’t let me do prototypes.

Attachment 6085
Hi David,

I saw where you filled in some circles inside the "cages" of the drawing. I was hoping for some stick figure bodies, but the circles are a good start. I am assuming that each circle represents a weight, rather than a body, and that the placement of each circle is where you expect that the weight will have the optimum effect on rotation of the Swinging Gym. You partially have it correct on the right half of the rotation, but the left side is way off. What you show would actually provide rotation if this were a Bessler type wheel built with multiple cages. Those who attempt Bessler wheel builds always wrestle with the problem of somehow having the weights outward on the way down, and moving them inward on the way up. The idea being, of course, that the outward weights will have enough leverage to lift the inward weights. The Swinging Gym cage suspension solves that problem by automatically shifting the outward weight to the inside on the way up. With wide enough cages, the weights could be kept very close to center on the way up. So there you have it - the solution to the Bessler wheel dilemma. As to the single cage Swinging Gym, though, it's an altogether different story. In the Swinging Gym, you want to be standing at full height against the right side of the cage for the 3 o'clock position. Why? Because this distributes your weight as close as possible to the outer arc perimeter, where it will have the most leverage. Only after you pass 3 o'clock should the knees begin to bend, and this is because you want to maintain your body weight as close to the arc perimeter as is possible. At 4 o'clock and 5 o'clock, the right side of the cage is moving further and further away from the arc perimeter, while the bottom of the cage is moving closer, so the knees continue bending to bring the rider's weight closer to the cage bottom and the arc perimeter. At 6 o'clock, the bottom of the cage is closely aligned with the arc perimeter, and the rider should be positioned at the center of the cage with knees bent the maximum amount. As the rotation continues, to 7 and 8 o'clock, the rider is progressively straightening the knees and moving to the left side of the cage in order to maintain a position as close to the arc perimeter as is possible. At 9 o'clock, the rider is standing at full height and pressed against the left side of the cage, where body weight is most evenly distributed as close as possible to the arc perimeter, just as in the 3 o'clock position. The reason for staying close to the arc perimeter on the way up, as well as on the way down, is to provide leverage and inertial thrust. Now there is a point in the upward half of the rotation where maintaining weight at the left side of the cage becomes a liability. As the cage moves on to the 10 and 11 o'clock positions, the left side of the cage is moving further and further away from the perimeter, and the rider is already standing at full height, so cannot get any closer to the arc perimeter unless he jumps up and grabs the top of the cage and lifts his knees up toward his chest. That would be too difficult, and too dangerous, for a Swinging Gym rider, so at about 10 o'clock the rider instead begins moving quickly towards the right side of the cage, making it to the middle by 11 o'clock, and fully to the right by 12 o'clock. This is the precise method used by any experienced rider to rotate the Swinging Gym. And, being an experienced rider myself, I assure you that this works quite well. Therefore, any proposals for mimicking the necessary human movements should provide not only for up and down weight shifting, but also shifting along a horizontal plane from cage side to side at the correct timing points.

Rick

Last edited by rickoff : 07-22-2010 at 06:14 AM. Reason: sp
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Old 07-22-2010, 08:36 AM
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Thanks David,

I'll check into that when I get back.
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Old 07-22-2010, 02:29 PM
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Hi David,

You partially have it correct on the right half of the rotation, but the left side is way off.

The reason for staying close to the arc perimeter on the way up, as well as on the way down, is to provide leverage and inertial thrust.

That would be too difficult, and too dangerous, for a Swinging Gym rider, so at about 10 o'clock the rider instead begins moving quickly towards the right side of the cage, making it to the middle by 11 o'clock, and fully to the right by 12 o'clock. This is the precise method used by any experienced rider to rotate the Swinging Gym. And, being an experienced rider myself, I assure you that this works quite well. Therefore, any proposals for mimicking the necessary human movements should provide not only for up and down weight shifting, but also shifting along a horizontal plane from cage side to side at the correct timing points.

Rick

Hi Rick:

In fact double fulcrums increase the radius substantially, compared with a single fulcrum.
I am assuming that your purpose is to mechanical mimic the swinging gym.
If we have an acrobatic and fast rider, I think the next picture shows your experience.

7 aaaaaaa.JPG

Ideally, in my opinion would be like this.

8a.JPG

If my opinion is right, the rider stays all the time on the right side of the cage, clock wise rotation and on the left if reversed.
I centered the cage, and limited the movement to up and down.
Thank you
David

6a.JPG
1a.JPG
4a.JPG
3.JPG
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Old 07-23-2010, 05:47 AM
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If we have an acrobatic and fast rider, I think the next picture shows your experience.

Attachment 6100
Actually, no. This is not what I described. I thought I had explained it clearly, but I guess not. Your attachment shows the rider standing at full height at the bottom, and that is just the opposite of what I stated. When I get back home probably next Tuesday) I will make a drawing clearly showing the rider positions.

Quote:
Originally Posted by Matos de Matos View Post
Ideally, in my opinion would be like this.

Attachment 6101

If my opinion is right, the rider stays all the time on the right side of the cage
I spent the entire summer of 1958, with a friend, perfecting the best means of rotating the Swinging Gym. It was our favorite ride at the amusement park, and we went on it several times every day, all summer long. It was a matter of trial and error, and believe me we tried everything conceivable to improve on rotational speed. We did try working the cage from just one side, as you suggest, but found it way more difficult and much less productive than when shifting from side to side. We became so adept at it that the ride operator began allowing us to ride for free, since he realized it was the best way possible to promote the ride to other people, and in the end he made a lot of money off of our efforts. This is kind of like riding a bike, in that once you get it right you never forget the method. I've shared what I learned from actual and considerable experience, regarding the Swinging Gym, and you can certainly disregard that knowledge if you feel it doesn't make sense to you. That's fine by me, but you will have a really tough time trying to convince me that the method which I have described is faulty.

Oh, and why is it that you say your country will not let you do any prototypes? Is prototype building illegal there?

Best regards,

Rick

Last edited by rickoff : 07-23-2010 at 06:01 AM.
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Old 07-23-2010, 09:20 AM
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Oh, and why is it that you say your country will not let you do any prototypes? Is prototype building illegal there?

Best regards,

Rick
I live in Luanda, angola, Southern Africa, and we lack everything.
Even if i find some parts, imported, there is no good machine shops or even skilled mechanists.
One 1.5 L botled water costs almost 2 USD and is imported.
David
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Old 07-23-2010, 05:07 PM
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Very informative thread. I have simulated some of Matos de Matos illustrations and they can spin. Even the standard pendulum rule, ie standing at 6 and crouching at 12 can make it spin.

I'm not sure what rickoff is proposing but I believe he's suggesting to use an additional dimensions namely left and right movement on top of up and down?

I could simulate them all next to each other to see which is most effective.
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Old 07-23-2010, 11:12 PM
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Your attachment shows the rider standing at full height at the bottom, and that is just the opposite of what I stated. When I get back home probably next Tuesday) I will make a drawing clearly showing the rider positions.

Best regards,

Rick
I draw it simple, but you are right, it should go like anelipse up towards the left, in the direction of centrifugal force and up.

Hi Broli

You are simulation with what tool?
Can you simulate my last thread:
Bessler wheel; how I see it
Thanks
David
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Old 08-10-2010, 05:41 PM
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Hi folks,

I spotted a possible opportunity to take some video of a Swinging Gym at the Bangor, Maine fairgrounds last week. It's a large annual fair where they have many amusement rides that could be seen from the highway as I was passing by on the way to my cottage. Hoping that they might have the Swinging Gym setup there, and having my video camera with me, I diverted course to the main entrance. Upon walking in at the main gate, I was surprised to learn that they were asking $10 simply for admittance. In earlier years I cannot remember paying a fee to get in, and only had to pay for the rides or games that I participated in. I explained that I was only there to take some video of the Swinging Gym, if they happened to have one, and that it would only take me a few minutes. I also told them that I wouldn't mind paying the $10 ticket price if I could be assured that they did have a Swinging Gym, but that I would not pay otherwise. After some haggling, and a call from them to the ride operators, they could not determine whether or not they had a Swinging Gym, so agreed to let me in for a few minutes to have a look. Unfortunately, although they did have several rotational rides set up, no Swinging Gym was to be found. I'll keep looking for one at some of the other fairs that I run across, and hopefully will find one in operation. It may be, though, as I stated earlier, that the Swinging Gym has been discontinued due to concerns over lawsuits filed by persons injured while using the apparatus incorrectly, and perhaps they have actually been banned in certain areas or states for that reason. So, back to the drawing board for the time being. I am working on some drawings that will illustrate the actual human movements used for both rocking and rotating the Swinging Gym, and will post those as soon as they are ready.

Best 2 all,

Rick

Last edited by rickoff : 08-18-2010 at 02:57 PM. Reason: sp
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Old 08-22-2010, 08:36 PM
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Swinging Gym Startup

Before the Swinging Gym can be rotated, a start-up sequence must be performed by the operator to increasingly swing the cage higher and higher until it is possible to go over the top dead center, or 0 degree mark. Thus, the operator must alternately swing the cage left and right by the method explained herein. Please refer to the following image:

http://public.blu.livefilestore.com/...tup.bmp?psid=1


Explanation of diagrams:

Figure 1: Before entering the Swinging Gym cage, the cage is at rest centered over the 180 degree mark, as shown by the dotted cage outline. Upon entering the cage, the human operator moves to the right side of cage, as shown in diagram a. Due to imbalance, the cage moves to the left to restore balance. Due to momentum, the cage will actually swing past the position of true balance before stopping, and will then reverse direction of swing. The objective is for the operator to move as quickly as possible to the other side of the cage just prior to swing reversal.

Figure 2: Diagram b shows that the operator has suddenly moved to the left side of the cage to shift weight. The cage has reversed direction, and is moving to the right. Diagram c shows the operator extending an arm in anticipation of a move towards the right side of cage as the cage nears its extent of movement. For safety reasons, it is always imperative that at least one hand is grasping a side bar firmly.

Figure 3: In diagram d, the operator has made a quick move to the right side of cage to shift weight. As the cage swings left, the operator stoops down and pulls on the right side bar while beginning to reach for the left sidebar. In diagram e,the operator moves to center of cage, has knees bent, is pulling on the right side bar, and pushing up on the left sidebar as the cage reaches the 180 degree mark. This additional effort increases the speed and momentum of the cage swing. As the cage continues swinging left past 180 degrees, diagram f shows the operator moving towards the left side of cage and standing taller while continuing to push against the side bar.

Figure 4: At the full extent of leftward swing, the operator is standing full height at the left side of cage in diagram g, and cage swing reverses towards the right. In diagram h, the operator begins to stoop lower, pulls on the left side bar, and begins reaching for the right sidebar. Diagram i shows the operator half way through a weight shift and pulling down on the left side bar while pushing up on the right side bar. In diagram j, the operator continues moving to the right side of cage while standing taller and pushing up on the right side bar. Diagram k shows the operator standing full height at the right side of cage as the cage reaches swing extent, just prior to reversal. The operator continues the movements shown in figure 4 until the arc of the cage swing reaches 90 degrees while swinging to the right, or 270 degrees while swinging to the left, either of which is half way to the top dead center 0 degree mark where full rotation can begin. At the 90 or 270 mark, the operator would turn to place his or her back firmly against the side of the cage while standing at full height. This increases the operator’s weight distribution advantage to maximum, while also facing the operator towards the direction of his or her next movement towards the opposite side of cage.

My next post will show how the operator continues movement past 270 degrees, and over the top to begin full and continuing rotations.

Last edited by rickoff : 08-22-2010 at 08:45 PM.
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Old 08-22-2010, 11:21 PM
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Swinging Gym rotation

My previous post showed how a human operator starts up the Swinging Gym by swinging the cage from side to side while increasingly swinging higher. To achieve rotation, and continue rotation, the human operator moves as shown and explained herein. Please refer to the following diagram, and keep in mind that there is actually only one cage involved, but that the diagram shows positions of that cage in twelve 30 degree increments:

http://public.blu.livefilestore.com/...ion.bmp?psid=1

Explanation of diagrams:

Upon reaching the 90 degree arc position, the operator turns to place his or her back firmly against the right side of cage. This positions the operator's weight for the maximum leverage avantage possible, while also preparing the operator for rapid movement towards the opposite side of cage. As the cage swings downward from the 90 degree position, the operator begins stooping lower in the cage by bending knees as shown at the 120 degree position, which places the weight concentration closer to the outer perimeter of the cage swing arc. At the 150 degree position, the operator continues to stoop lower and pulls on the cage's right side bar while advancing towards the middle of cage. At 180 degrees, the operator is centered in the cage and stooped to lowest position while pulling down on the right side bar and pushing up on the left side bar. The movements between 150, 180, and 210 degree positions are naturally more fluid than shown by the diagrams, with the operator continually leaning and moving leftward. At 210 and 240 degrees the operator is at the left side of cage and extending the knees to stand taller. At 270 degrees, the operator turns to face the opposite side of cage, placing his or her weight firmly against the left side of cage to attain a positioning of weight distributed at the outside perimeter of the swing arc. Whether the cage swings further upward, or begins swinging downward at this point, the operator is in the best position to retain or increase momentum. If the swing arc reached 90 degrees on the right side, then it should go higher than 270 degrees on the left side, so let's say the cage is now at the 300 degree position and moving towards 330 degrees. At this height, remaining at the left side of the cage becomes a liability, so he or she must begin quickly moving to the right side in order to maintain forward momentum for as long as possible. If the cage should stop, and reverse direction before reaching 360 degrees, the operator must quickly return to the left side of cage. Those who do make it to the top find that the cage will slow to nearly a dead stop as it approaches 360 degrees, and that only by throwing the body weight hard against the right side of the cage are they able to get over the top and rotate downwards. As soon as the top is cleared, the operator should turn to place his or her back against the right side of cage, and maintain a full upright position. It would be even more advantageous at the 0, 30, and 60 degree positions to jump up, grab the top of the cage, and hoist the body upwards as high as possible to get closer to the arc perimeter, but this would be too dangerous to attempt. Furthermore, once over the top, it takes less effort to maintain rotation than it did to reach the top the first time around. The operator continues a clockwise rotation by means of the body movements shown at each successive 30 degree diagram, and increases speed of rotation by exerting more emphasis on pulling down and pushing up the cage sides while stooping and extending the body.

As mentioned earlier, one can feel quite physically exhausted through the efforts it takes just to reach the top, but once over the top it is relatively easy to maintain rotation if the body movements are applied correctly. While the Swinging Gym is purposely constructed to give the operator a tough workout, it could just as well be made to ease the burden of the operator by affixing heavier counterweights on the suspension arms, or lengthening the extensions of the counterweights. For example, the cage alone, even though counterweighted somewhat, has enough weight to easily return it to bottom dead center (180 degrees) with no operator aboard. Let's say that the cage weight, minus the counterweights, is perhaps 50 pounds. If a 150 pound adult operator enters the cage, he or she must not only lift their own weight, but the extra 50 pounds as well, for a total of 200 pounds, and that requires considerable exertion. If the counterweights were increased to the point where the operator only had to lift 50 pounds, for example, the effort required by the operator would be just 1/4 of the previous amount. Reducing the effort required further below 50 pounds of lift would have a drawback, though, in that loss of weight induced momentum would make it difficult to achieve rotations capable of performing any useful work.

Hopefully, these last two posts will make it easier for all readers to visualize the methods of swinging and rotating the Swinging Gym, and to understand the human movements necessary. One could attempt to build a full size, or scaled down, version of the Swinging Gym and rig an apparatus to mimick the human movements of weight shifting, but there is another way to accomplish weight shifting on the up and down sides of rotation that would be much simpler to facilitate, and I will talk about that in my next post while explaining how and why the Swinging Gym may well be the ideal model for a self running gravity mill if adapted properly.

Best 2 all,

Rick

Last edited by rickoff : 08-22-2010 at 11:32 PM.
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