pic: VEX High Reduction Gearbox
 

Check out videos at:
http://www.youtube.com/watch?v=l5OQ8LdEcvo

Re: pic: VEX High Reduction Gearbox
 

This is something goofy I made which is inspired by the concept of a millennium clock. I've made plenty of things which spin really fast, but I've never made something which spins VERY slow; I think this qualifies.

I use it as a lesson for Robowrangler students. I ask them to calculate some things as a way of proving they learned their gear theory.

I thought maybe someone here would think it is cool.

-John

Re: pic: VEX High Reduction Gearbox
 

Hmm... I'm suddenly tempted to add a year hand to my LEGO clock.

Re: pic: VEX High Reduction Gearbox
 

Is it even possible to turn the little wheel by hand?

This is one of the most ridiculous/amazing things I've seen recently.

Re: pic: VEX High Reduction Gearbox
 

Thanks!

No, it takes a lot of effort to turn even the 4th 60t gear from the input. I've had this gearbox sitting on my desk for a few months and every so often someone gives it a spin. Even after all this time we've been unable to advance the small wheel a noticeable amount (you can see the sharpie line we added when I first built the gearbox on the top of that wheel.)

-John

Re: pic: VEX High Reduction Gearbox
 

Wow... with that kind of gear reduction... I bet you could move the Earth!

...well... provided the gears don't explode first... :o

Great nonsensical gizmo. I think I'll dub it the Neunian Reduction Box for my memory.

-q

Re: pic: VEX High Reduction Gearbox
 

If my 24 hours of lemons team took this with us driving from Detroit to San Francicso, strapped on the back of the back of the race-car for the full length of the race, and then drug it back to Detroit, the little wheel would have only turned about 40 degrees.

Another way of looking at this is 1 JVN small wheel degree is equal to about 168 miles. In order words, our trip to Atlanta this spring is only 4.5 JVN small wheel degrees. That doesn't sound so bad.
:yikes:

Re: pic: VEX High Reduction Gearbox
 

This is the kind of goofy stuff I make my students calculate.
It is an awesome learning aid. It makes a pretty cool piece of desk art too.

Re: pic: VEX High Reduction Gearbox
 

How's that Fluids studying going? ready for the final?

Neat gearbox...in the old days cars used to have mechanical odometers. The cable driving it turns 1000 revolutions per mile. The odometer has 6 digits, the first one turns one revolution per mile. I guess it's a similar concept.

Re: pic: VEX High Reduction Gearbox
 

Reminds me of something the artist Tim Hawkinson made once. A ridiculous gear reduction, where the input spun at several thousand RPM, and the output would take hundreds of years to make one revolution.

Re: pic: VEX High Reduction Gearbox
 

haha... I was just yesterday teaching our new team members about planing a good reduction gear assembly. I'll show them this picture ;)

Re: pic: VEX High Reduction Gearbox
 

dang you got busted !!!!!!

thats really cool john

Re: pic: VEX High Reduction Gearbox
 

I think this is awesome. I think I am going to borrow the idea for my team, but we are going to make a "Shipdate countdown clock" So Whatever day they build it they will have to calculate the right ratio for a ~60 day output cycle.


Now the real question, has anyone ever run a vex controller for 60+ straight days using a power supply?

Re: pic: VEX High Reduction Gearbox
 

I think the makes it reasonably possibly to accelerate the larger wheel to the speed of light.

Re: pic: VEX High Reduction Gearbox
 

If not for that pesky friction....

Re: pic: VEX High Reduction Gearbox
 

Also inertia :(

Someone please correct me if I am wrong but wouldn't you be fighting a force of 1/12(mass)(3*radius^2 + height^2) * 244140625 Newtons to get it started? Now, maybe if you put a crazy long lever arm on the small wheel's shaft you could over come that.

Of course, even that number is almost nothing compared to the real number because you would have to account for starting the gears rotating too. This could be an interesting problem for more advanced students, What is the max length of a lever arm you could attach a 100 kg weight to and still not have the large wheel move? Have them run it both ways.

But very cool John.

Re: pic: VEX High Reduction Gearbox
 

What I want to know is what the backlash is at the input gear. It has to be several thousand full revolutions of the input shaft. Which amuses me to no end, given I'm usually working with gearheads that measure backlash in minutes of arc....

Re: pic: VEX High Reduction Gearbox
 

Now try replacing all those medium gears with the large gears. :D

Re: pic: VEX High Reduction Gearbox
 

Cool gearbox, JVN!

We had a guy call us this past summer, wanting to use a Toughbox and a low power motor to slowly move a parabolic solar panel so that it follows the sun.

So... we found a small gearmotor package from Dayton, and used that as an input to the Toughbox. We bench tested this assembly and found out that the output shaft of the Toughbox was doing 1 revolution in about 18 minutes. Of course, this is much faster than the Earth is spinning, but it was a good way to use a very low power motor to move a 12 foot long solar panel.

AB

Re: pic: VEX High Reduction Gearbox
 

Now lest see you "back-drive" that!

Re: pic: VEX High Reduction Gearbox
 

Have you seen the mini jet engines that are in the fancy rc planes? Some of those spin up to around 150,000 rpm. At that rate it would take a little over a day to turn the wheel.

Re: pic: VEX High Reduction Gearbox
 

It's going to move the large wheel if you apply any torque to the small wheel at all, the amount of torque just determines the acceleration, which will be tiny for any reasonable amount of mass. The only thing that might actually stop the entire thing from rotating is the friction in the bearings, which I don't think is very large.

Re: pic: VEX High Reduction Gearbox
 

Thanks, you can tell it has been a while since physics.

Re: pic: VEX High Reduction Gearbox
 

That is, before the thing starts melting or grinds itself into pieces...

Re: pic: VEX High Reduction Gearbox
 

Wow. This is just plain cool. =]

Re: pic: VEX High Reduction Gearbox
 

Heh - very cool. If you could "drive" the big wheel from the Earth to the Moon (at apogee, the approximate distance is 251,968 miles), the little wheel would turn only 4.1629 times.

-dave



.

Re: pic: VEX High Reduction Gearbox
 

Say we're driving on the big wheel to Mars ... how many little wheel turns?

Re: pic: VEX High Reduction Gearbox
 

At closest approach (such as during the perihelic opposition in August 2003) the Earth-Mars distance can be as small at 34,646,418 miles. In that case, the little wheel turns 572.418 times. During conjunction, such as the one just ending this week, the distance can be approximately 247,821,000 miles. In that case, the little wheel turns 4094.437 times. I would find that number to be excessive, so for a Mars transportation application I would want to add on at least one more 12:60 reduction stage. :)


-dave



.

Re: pic: VEX High Reduction Gearbox
 

I would like to thank both John and Dave for finally making me understand how far away mars is :D

Re: pic: VEX High Reduction Gearbox
 

All I can say is - we are such geeks!

Re: pic: VEX High Reduction Gearbox
 

Totally... and proud of it.

Are there people out there who don't geek out over stuff like this? Weirdos...

Re: pic: VEX High Reduction Gearbox
 

Arthur Ganson has a sculpture at the MIT museum called "Machine In Concrete" that consists of a 12-stage geartrain, where each stage reduces the speed of rotation by a factor of 50. The left end is spinning furiously at around 200 rpm; the right end is embedded in a concrete block. The end in the concrete makes one revolution every 2 trillion years or so.

Here is a partial picture of the machine from Ganson's own website:
http://www.arthurganson.com/pages/sc...te%20page.html

But to really appreciate it, you can see a video of the sculpture (and Ganson's comments about it) at the 8:30 mark in this video from the 2004 TED conference:
http://www.ted.com/index.php/talks/a...sculpture.html

Re: pic: VEX High Reduction Gearbox
 

I have always wondered how fast you would need to spin something for it to spontaniously combust.... care to give it a try??:p :p :p

Re: pic: VEX High Reduction Gearbox
 

Along these same lines anyone care to predict what the lifespan of a vex motor constantly running would be?

Re: pic: VEX High Reduction Gearbox
 

I don't know the answer, but we're certainly thinking about doing the same thing :)

Re: pic: VEX High Reduction Gearbox
 

Thanks to senior Petra Hartman LMHS now has its own version of the JVN High Reduction Gearbox to teach gear theory to 1712 members and students in the Engineering Design classes. Woot!

http://www.chiefdelphi.com/media/photos/33863?
http://www.chiefdelphi.com/media/photos/33864?

Re: pic: VEX High Reduction Gearbox
 

This gearbox was on display in the 148 pit in Atlanta this year. I noticed quite a few people playing with it.

Re: pic: VEX High Reduction Gearbox
 

I spent a few minutes playing with it, and trying to explain it's coolness to some parents, they didn't share my enthusiasm for it.

Re: pic: VEX High Reduction Gearbox
 

i think it would be fun to make one of these gear reduction towers and make it turn once every 42 days... the 42 days is completely an arbitrary number :)

Re: pic: VEX High Reduction Gearbox
 

John -

In the spirit of absurdly high gear reductions, maybe next year you should put something like this on your drivetrain as soon as it is constructed. Paired with a ratcheting rectifier, you can make yourself a pretty nifty odometer. I've always been curious to know precisely how many miles a 148 robot travels in the course of build, practice, and competition...

Re: pic: VEX High Reduction Gearbox
 

Apparently there are others outside the realm of FIRST that geek out about this too.


http://jalopnik.com/5302043/on-the-p...-transmissions

"Artist Arthur Ganson's creation called "Machine with Concrete" provides a beautiful illustration of the power of a transmission. Should you input only 1 lb-ft of torque, the other end could deliver 244 quintillion lb-ft.

Ganson's piece demonstrates the unbelievable power which can be generated through simple gear reduction. It uses an electric motor turning at a modest 200 RPM and mates it to 12 identical sets of 1/50th gear reducers for a total reduction of 1/244,140,625,000,000,000,000. Of course no material in the universe could actually deliver that kind of power without shattering into pieces and even if such materials existed, turning only one rotation at that speed would take over two trillion years. It turns so slowly that embedding the final drive in concrete will have no appreciable effect — ever. The universe itself is only about 10 billion years old, and in another 10 billion years the sun will expand into a red giant and consume the Earth anyway, the final drive having complete only 0.5% of one rotation."


My emphasis added to my favorite part.