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Author Topic: overbalanced chain drive  (Read 56250 times)

oscar

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overbalanced chain drive
« on: June 03, 2009, 06:50:13 AM »
 :-*
In order to understand the concept that is presented below, you may want to first have a look at the overbalanced chain drive featured on the web page http://www.besslerwheel.com/murilo/index.html

Before proposing some changes to that original idea I want to first analyze it a little.
On the left side of the mechanism there are more chain-links than on the right side. That makes the left side heavier.
So I will refer to the side with more chain-links as "the downward moving side or heavier side" and to the side with less chain links as "the upward moving side or lighter side".
Since the weights on the heavier side are pressing down onto the lower transport sprocket, that sprocket will start to turn, transporting chain-links to the lighter side.

The main requirement for perpetuity of that motion is the following:
The upper and lower transport sprockets need to be synchronized, so that while the lower transport sprocket turns and 1 chain-link is moved from the downward moving side to the upward moving side, the upper sprocket must do the same in reverse to refill the heavier side.
Both sprockets have to transport the same number of weights during each timespan so that the weight difference between the two sides is maintained.

Murilo Luciano's design on the quoted website aims to achieve this by means of two sprockets which are in contact with the same number of chain links and turn at the same speed/rpm.

To achieve the synchronized rotation of the sprockets, he employs a special chain. Each link of this chain has a little "strut" which is automatically engaged while on the upward moving side. The struts prop up the chain links when they are unfolded and keep them in an extended state. The struts prevent the links on the upward moving side from collapsing/folding.
In this way a tower is built on the upward moving side, with all the weight of the stacked links resting on the lower ones and all together on the lower sprocket.
Since the number of links on the underbalanced side is less than on the downward moving side, the design seems valid.

The struts disengage when the chain links are transported to the heavier side. Consequently they will fold. The height they occupy is now less than when they were in the propped up state.

If this basic idea is valid, the main technical challenge is to achieve reliable operation of the struts, that is of their automatic engagement and disengagement.

Since I had difficulties to envision this mechanism working reliably I have tried to alter the idea, so that no struts are needed.

In the design proposed here (see drawing below) the upper transport sprocket will (hopefully) pull up the extended chain from the underbalanced side at the required synchronized speed.
This is supposed to work like this:

The upper and lower transport sprockets are of the same size but the number of chain links they are in contact with is different, since the links transported by the lower sprocket are folded, whereas they are extended when they pass around the upper sprocket.

So the two transport sprockets need to turn at different speed/rpm, yet in a synchronized manner.
They are synchronized by use of an additional normal chain (bicycle chain) or a timing belt, indicated in magenta.

The bicycle chain drive is meant to be powered by the lower sprocket, driving the upper sprocket at the required speed.

The gear ratio for the bicycle chain drive in the depicted setup has been determined as follows:
The two transport sprockets in the sketched example have the same number of teeth (24).

- The behavior of the lower transport sprocket:
When it turns 1/24th of a full revolution, it transports 1 link to the other side.
In other words: when it goes round once, it will have transported 24 chain-links.

- The behavior of the upper transport sprocket:
In order to transport 1 chain link to the other side, it needs to turn 5/24th, that is ca. 0.2 of its circumference.
In order to transport 24 chain links, it will have to turn 5 times.

So the gear ratio (turns of lower sprocket vs. upper sprocket) needs to be 1:5.
This can be achieved with a lower sprocket of 100 teeth and an upper one having 20).

Known issues:

-issue1:
the proposed design needs guides (guide rails) on the downward moving side to prevent weights/links from being squeezed out to the side due to pressure from others resting above them.

-issue2:
smooth feeding process of down pressing links to the lower sprocket

-issue3:
it must be ensured that the "connection plates" of the chain links fold outward (i.e. away from the machine) when the chain links come off the upper transport sprocket.

I am contemplating to build something along this line as a proof of concept.

If anyone who has experience with mechanics instantly spots that I overlooked something and/or that this can never work because ....,
or if I can save myself some trouble if I take other important facts into account ...
please make yourself heard in this thread.

I have attached the .dxf-file which was used as a base for the image.

FreeEnergy

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Re: overbalanced chain drive
« Reply #1 on: June 03, 2009, 06:57:13 AM »

Cloxxki

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Re: overbalanced chain drive
« Reply #2 on: June 03, 2009, 08:56:46 AM »
@Oscar:
Thank you for bringing this idea back under the attention. I already liked its simplicity, but you've taking it to the next level!
On technical obstacle you might save yourself, is the 5:1 ratio. Go 1:4 or 1:6, to be able to pin the weight chain links with a little bicycle chain like bushing, which also fit over the upper weight sprocket's teeth. Now your chain seems to have a floating pivot point. It can certainly be done your way, but perhaps not as practical as you might.

Must say I'm impressed with you heavy side guide rails. I would propose to make the out one taller, to further enhance smooth transition. The inner might even be curved with the sprocket.

I have been looking at using an existing $3 bicycle chain as weight chain. NOt very far yet, but if feasible, it would aid replication.
Imagine we manually fold the chain as it would rest on the heavy side. We could be as modest to make the stack only 2 links wide, but more seems better here, why not 6 links wide?. You'll see the pins will not all 180 degrees. But that's fine. Just weld the "flat" ones shut. Leavint the outer pins to pivots as they're used to. Providing sufficiently welded, the chain would (with tapering guide rails encosing the whole stack from upper sprocket to top of stack and then parellel to botom of stack?) nicely fold as we first designed it to do.
On the light side, a guide box would for the chain in its extended position. The welds are supporting it laterally, it can't do anywhere.
Being a regularly pinned bicycle chain, the action on the upper sprocket will be more awkward. But, the light side box containing the extended links might aid the timing. Most complicated will be the lower sprockets, but if this chain drive is to work, even a welded bicycle chain can be made to work.
Alternative to the welds, someone with plastic fabrication technology to his/her disposal, might be able to product "toy" quality plactic strutsturning a standard $3 bicycle chain into a "welded" one, once this idea works, for international implementation, science fairs, etc.

I can't fault the chain drive, and it baffles me the thing is not better documented (dozens of failed devices is what one would expect, it being so incredibly obvious). FE instinct says "it will jam" but where?

I hope this thread will deserve the attention and support it deserves, or someone will soon offer the reason we are missing as to why this one also will not work.

Regards,

J

quartz

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Re: overbalanced chain drive
« Reply #3 on: June 03, 2009, 12:23:06 PM »

helicalred

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Re: overbalanced chain drive
« Reply #4 on: June 03, 2009, 04:09:20 PM »
The difference in the number of links (mass) on either side is not the only consideration. The links on the right must be accelerated to five times the velocity of those on the left. It appears to me that the system would be in equilibrium.

Regards, Bill

Cloxxki

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Re: overbalanced chain drive
« Reply #5 on: June 03, 2009, 05:12:44 PM »
The difference in the number of links (mass) on either side is not the only consideration. The links on the right must be accelerated to five times the velocity of those on the left. It appears to me that the system would be in equilibrium.

Regards, Bill
That's what came to me earlier today as well, that acceleration... Then, the chain is also "slamming down" on the heavy side, one might argue. Can the total weight even be used, if it only lowers 1 chain link at a time?

TinselKoala

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utilitarian

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Re: overbalanced chain drive
« Reply #7 on: June 04, 2009, 05:37:32 AM »
I hope this thread will deserve the attention and support it deserves, or someone will soon offer the reason we are missing as to why this one also will not work.

Regards,

J

Even if you assume no friction anywhere and everything slides past each other like well oiled cupcakes, there is no energy gain to be had. 

I think Simanek probably explains it best, but in sum, each little descending link on the heavy side has to push up a link on the light side.  But if you add up the weights of the links on the heavy side, they will produce exactly as much energy in their descent as is required to balance the lighter side, not an ounce more.  This is because they have to push the lighter side a greater distance. 

The heavy side is all bunched up, and can only descend a little bit.  The light side has only a few links, so they have far to travel, compared with the heavy side.  So everything is still even steven.

Cloxxki

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Re: overbalanced chain drive
« Reply #8 on: June 04, 2009, 09:14:39 AM »
Thanks! There's always something making a machine not work, isn't there? Now I know one more place not to look.

murilo

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Re: overbalanced chain drive
« Reply #9 on: June 07, 2009, 06:38:31 PM »
Hello, guys!
Thanks to you and to Oscar!
My time is too short, but I have stuffs to tell you about my avalanchedrive.
I`ll send just some tips:
- please, try to learn about exactly as shown at besslerwhell.com, where even a power-point presentation is given.
- it`s a clean diagram and everything is there. Besides mechanically to PULL is better than PUSH, this is the simplest way to prove the concept, FOR THE WHILE!
- if that ``U`` shaped stack shown in my matter, at the end, offers one side higher than the other, all the system will be validated. :)
- in this closed system, one side will cancel to the other, BUT in my conception this will hapen if you leave it to free and natural gravity fall.
- if all system is not free but HOLD in the under wheel axle, let`s say, just 50 or 40 RPM, a SURPLUS will be evident in the form of torque, or torsion. ( this is very important )
- Don Simanek didn`t understand to my conceptions and he insist in the Roberval balance... ( ? )
- he can`t see that the reverse weight to be pushed will be discharged in at least 3 hold points in the wheel, since the formed triangles will transfer it, as an armed structure.
- CASE Don Simanek is right, but he isn`t, enough will be if we enlarge the wheel`s radius to 3 or 4 times the chain`s width. :)
- OF SURE, lots of mechanical contact is all around and all them conduced by gravity... and this is a must!
- the articulated differently formed bodies, or parts, USE gravity to be stand up. There is touch and contact but it is a part of mechanism.
- only when the chain is opening and shutting is when one will find some ``active friction`` operating in those small angular axles.
- VERY IMPORTANT, when the chain is getting open state this will happen at a higher radius, outside in wheels periphery, already in the rise higher velocity - this is calculated.
- the chain MUST be hooked at that sprocket, or wheel. When sustained by the hooks ALL the mass will be applied there, casing the most clear torsion and turn.
- NOTE that all points above are mentioned without considering ANY occurrence of kinetics and any acceleration... :)
- kinetics and acceleration will be the natural gift to the system.
- the top wheel must work free and passive; not a big deal.
Later on, I`ll try to put some draws here.
Tell me where it brakes... I can`t!   
Thanks again,
best regards.
Murilo

Cloxxki

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Re: overbalanced chain drive
« Reply #10 on: June 07, 2009, 09:12:20 PM »
Hi Murilo, thanks for explaining yourself here.

I see how the outer weights on the chain at least accelerate themselves using gravity. The increased distance at 6:00 is then maintained, which is fighting gravity.
The inner weights though, increase distance right after 3:00 on the lower wheel, it seems? Do these then not accelerate after that constance wheel speed?

Please educate us how the energy transfer works.
I see that when the left stack drops 1 chain link (let's say 1cm):
- 2 weights x 1cm worth of energy is freed
- On the light side, 2 weights x (let's take) 2 cm of work is done
- On the heavy side 2 weights x 1cm are added to the stack.
This evens out, it seems?

I wonder what we are missing here.
In zero friction, I'm sure it would continue at the same pace forever. In reality though, I see it coming to a halt by lack of surplus energy.

Please enlighten us!

Thanks,

J

murilo

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Re: overbalanced chain drive
« Reply #11 on: June 08, 2009, 12:03:46 AM »
Hi Murilo, thanks for explaining yourself here.

I see how the outer weights on the chain at least accelerate themselves using gravity. The increased distance at 6:00 is then maintained, which is fighting gravity.
The inner weights though, increase distance right after 3:00 on the lower wheel, it seems? Do these then not accelerate after that constance wheel speed?

Please educate us how the energy transfer works.
I see that when the left stack drops 1 chain link (let's say 1cm):
- 2 weights x 1cm worth of energy is freed
- On the light side, 2 weights x (let's take) 2 cm of work is done
- On the heavy side 2 weights x 1cm are added to the stack.
This evens out, it seems?

I wonder what we are missing here.
In zero friction, I'm sure it would continue at the same pace forever. In reality though, I see it coming to a halt by lack of surplus energy.

Please enlighten us!

Thanks,

J
Hi, J.
Thanks for your time.
At 3h the inner weights will open, assuming the straight line, almost without take any energy out of the system.
As you said, it would work forever with zero friction... and I say it will because the friction is really small if compared to the falling mass.
Remember, the falling mass is hang, or suspended, by the wheel`s periphery hooks, which axle points are supported by ground.
This means that for the opening of small axles at 9h to 7h, it doesn`t mind the total weight of that condensed pile.
The liberation of the chain will also ``cost`` a little when compared to the applied masses.
Many times I ask myself about ``what are we forgetting here``.  Since there are no responses, I say it will turn free and cold for long, as any other mechanical device... :)
The mechanical situation is similar to the act of hold a balance plate that ``wants`` to fall down... with no rest!
Remember the point where I said that the fall velocity will be hold by a charge, or break, as wished, at wheel`s grounded axle and that the acceleration will come to be a plus( ~1m for first second).
This is a good puzzle, isn`t it?
Cheers! Murilo

Cloxxki

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Re: overbalanced chain drive
« Reply #12 on: June 08, 2009, 12:57:27 AM »
Thank you for your elaboration Murilo.

As much as I want to believe in the strength of that heavy side...I see that for each link it's lowered, the light side has to rise that same weight much higher.
Perhaps you'll end up being right. That the fact that the heavy side is being kept heavy prevent equilibrium to be reached.

Have you ever started creating this wheel?
However smart your high-tech collapsing links are, I think that to test the idea, a simple bicycle chain with some changes will work just fine.

You brought me to an alternative idea.
In stead of your collapsing links, there are now springs. Just a V shaped spring steel rod to start with, weights at each point.
The springs totally fold under 5+ links of weight, but expand when the load comes off (after 6:00) So, the increased distance between the light side's weights now come from springs. It remains the light side, again due to the strictly timed upper and lower cogs.
Trick: we'd need spring (systems) that collapse prograssively under load, allowing the heavy stack to be the same height while housing more stacked weights. I suppose the springs ends (tops of V) would have to be sliding down incresingly curved slopes. Above the maximum load to be attained on the right side (say, 4 increasingly but yet far from completely collapsed springs), the collapse is so great vertically that the height is reduced to less than the light side. A quick slap would collapse the light side too, but we're not doing that.
When the load on a spring (bottom of heavy side reaches 5 weight, the spring collapses completely. The thin weight resting on each other. 7 heavy side weights (3 collapsed, 4 partially would take the equivalent height of 4.4 or so on the light side. Smart gearing might overcome that difference already. More complicated sping-linking might allow the 2nd weight in a stack of 5 (normally only bottom one collapsed) to also collapse. Like domino game. But, only after the 5th weight is added, it collapses from the bottom. Like a demolished building.
Which only room for 4 on the light side, collapse doesn't happen.
As long as the springs once passed at 6:00 do indeed fold open to full height again, I do see a way for this to work. Please show me where I'm wrong :-)

helicalred

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Re: overbalanced chain drive
« Reply #13 on: June 08, 2009, 12:03:58 PM »
Murilo,

I tried this thought experiment: I imagined your machine lying horizontal and stationary. Then I imagined it being tilted into a vertical position when gravity should have come into play and started it moving. But I'm sorry to say I just couldn't visualize it starting to move of its own accord.

- NOTE that all points above are mentioned without considering ANY occurrence of kinetics and any acceleration... :)
- kinetics and acceleration will be the natural gift to the system.

Yes, - well OK - but sooner or later you do have to consider kinetics and acceleration but in my opinion they wont be much of a gift. I don't doubt that your system is capable of movement given some applied external force and that in the absence of friction etc it would then rotate for ever, but then, so would a flywheel. 

Regards, Bill

fletcher

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Re: overbalanced chain drive
« Reply #14 on: June 08, 2009, 11:49:30 PM »
I should imagine that it would temporarily work if the gearing were NOT in sync - then the side with more compressed links would slowly lower its CoM [compared to the other side] - the result would be the the entire CoG of the device would find its lowest level i.e. lowest position of PE - then it would stop [much like a chain driven pendulum clock needs the drive weight lifted periodically after gravity has acted on it] - as soon as the gearing is in sync [so that no Pe is lost (no height lost)] then all forces would probably be in equilibrium & the work done [fxd] would be the same on both sides of the vertical axis, as has been said.

A simple test might be to build a simple elevator system with pulleys top & bottom - have this geared to a separate pulley arrangement - 4 weights falling [under gravity] 1  unit of distance attempting to lift 1 equal weight 4 units of distance at 4:1 gearing ? - then change the gearing ratio up or down & see that one or other side wins depending on the new ratio.