Show HN: Sketch, connect and simulate gears and chains

Great arrangement! It will work. Whether it will be financially feasible to construct such a large system of gears, deploy it in extreme weather, keep it well oiled and maintain it, and then transport the generated power to a usable location are entirely different questions.

1. How is that calculated?

2. Is there a ready way to simulate it?

Of course it would "work". So would a lever - ask Archimedes:

http://en.wikipedia.org/wiki/File:Archimedes_lever_(Small).j...

Think about how large the forces will be at the first tooth interface at the left (or in the rack). How strong does that tooth need to be?

Alternatively, you can use it the other way. Connect the gear at left to a tectonic plate. Rest your finger on the gear at right. Voila! You can exert a force great enough to stop the tectonic plate's motion. Plausible?

When Archimedes said, "Give me a lever long enough, and a place to stand, and I'll move the Earth.", he actually meant something more like, "Give me a lever long enough, and a place to stand, and I'll change the momentum of the Earth very very very slowly. Unless that lever is incredibly strong and I have access to a considerable source of energy."

There's an art/science experiment piece on display at the Exploratium (unfortunately I can't remember what it's called) that has a similar construction. The gear at one end is turned at a steady pace by an electric motor, and each successive gear attenuates the motion until you get to the last gear, which is set into solid concrete (iirc). If it were free to move, it would take a fantastic span (billions or trillions of years?) to make a full rotation.

Edit: Thanks to bockris for pointing out the name. Turns out the last gear rotates once each 13.7 billion years.

no because speed is nothing without torque.

The right wheel would spin fast, but anything put there to leverage that momentum into energy, be it simple magnetic generator, would be enough to halt the whole system by equalizing the opposing forces, since whatever minimal force it has, will go trhu the same powers that create the initial speed.

So the total gear ratio of that gearchain comes out to something like 1119:1, though that's lower than you intended I suspect because you geared it down with a 9:57-or-so ratio on the end. The penultimate axle is geared at 7089:1 with respect to the first axle.

Now while that implies a rotation of one degree of the first axle is accompanied by a rotation of the penultimate axle through 20 or so revolutions, in practice that's not going to happen, because of that ton of friction you pointed out. The friction force acting to stop the last axle turning gets fed back as resistance to your pushing the first wheel, and it gets multiplied back up through the gearchain by the same factor - so the resistance to your turning the first wheel is 7000-times the resistance of turning the last wheel - plus 2000 times the resistance of turning the wheel before it, plus 918 times the resistance of the wheel before that... in total, assuming all friction forces are equal, you're fighting against a force 12000 times the force you need to turn just one gear - just to beat the friction. Okay, so you posit some frictionless maglev bearings in a vacuum, perhaps. But you still want to get these wheels into motion, so then the same multiplier gets applied to the force you need to accelerate the mass of each gear into (rotational) motion in the first place. Getting all those gears spinning requires 12000-times the acceleration to get one of them turning, so 12000 times the force.

And forget about putting a useful load on the end axle - let's put this thing in a car, say, and use it to drive the rear axle. We'll lift up the rear axle and get the engine up to 5000 RPM. Your engine is going to get that axle spinning 7,000 times for every engine RPM - 35 MILLION revs per minute! But when you drop your 1-ton car to get some traction, the engine's going to act like the car weighed 7000 tons...

You could also think of it in terms of energy. If that last gear spins at thousands of RPM, its got a huge amount of kinetic energy from somewhere. It must have come from your 'tiniest push'. Your tiny push has to transfer all that energy - so it can't be that tiny.

tl;dr: no.

It would work, but it would probably not be practical in terms of materials - any significantly huge gear ratio driven from the low-motion side will run into problems with the strength of the gears and the degree of friction involved (and the steady-state static friction pressure & friction loss per second of the fastest gears being sufficiently large to make it impossible to move the slowest gears at all)- and even if you have an impossibly strong frictionless gearbox, the strength of the contact patches with the objects themselves becomes the weak point - the pressure will impress a hole right through the tectonic plates, rock, or glacier you're dealing with, rather than spinning the gears.

Totally the first thing I thought of as well. Great idear.

Absolutely what I was about to post. For a mouse user, mimicing the circle construction mechanics (with preview!) used in the geometry construction puzzle app that was linked a few weeks back [1] would be the bee's knees.

1: http://www.sciencevsmagic.net/geo/

Agreed, and some controls that allow you to specify the radius of a gear instead of drawing it would help, too. I spent a long time trying to draw two gears with the same number of teeth on my ^#$(@#! trackpad. :)

Also, there's a UI limitation with snapping concentric gears together: you can snap a small gear onto a larger one, but not the other way around. This seems to make it impossible to add a pair of concentric gears whose smaller gear is meshed with the edge of an existing gear.

But overall, great project with very pleasant casual interaction. Would be interesting to see what you plan to do with it.

Rods and cams would be the next logical step.

Will probably send a pull request just to be able to draw gears by the diameter or radius instead of the perimeter.

can't even draw a square with the clitmouse...

In case you're interested, here are two of the best video's I've seen describing how a watch works ( http://www.youtube.com/watch?v=OiCPu0SjEW4 ) and how a differential works ( http://www.youtube.com/watch?v=K4JhruinbWc&t=1m50s )

Don't let their old school-ness throw you off. They are both extremely well done and demonstrate in clear and simple language from first principles to finished object.

Hah, the first thing I did was build a going train. I had to use belts for the second, third, and fourth wheels because the planarity was difficult or impossible to manage.

It was of course more like an electronmechanical clock since there isn't a way to build a balancewheel and escapement, but since I had to eyeball the gear sizes and draw them with my mouse anyway, it now appears to be approximately 0:65:101am.

Drawing a slash through a gear seems to delete it. I'm not sure whether or not that is intentional

draw a slash though the gear to delete.

I learned a bunch by watching the demo (big ? on the right)

I tested it on my 2010 android phone and it just barely works on that. More recent android tablets should be able to run it quite smoothly.

I just tried it on Chrome on desktop and it is usable. I think the touch just makes the experience better.

Using it with a touchpad is far from ideal, but you should be able to manage it by drawing the chain very widely around the gears. The chain will be tightened automatically.

Same problem on my Galaxy Nexus, I tried all combinations of placing a belt, and it just wouldn't work.

You need to create two gears, a big one and a small one, then place the small one directly in the center of the big one. You can then attach a chain around a gear. Took me forever.