Hypocycloidal gear train

Hypocycloidal gear train. For other physics animations like this one, please visit http://web.ncf.ca/ch865

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[Broadsmile1987]

Do You (in)put the force to small or big gear? I guess that to big, because small moves. So if You put it to the big one, why aren't the small one just rotating in place? Is it because of the teeth shape?

[PelletierPhysics]

@Broadsmile1987 There are 2 inputs. If you apply torque to the ring, and another torque to the shaft, then the small gear will have to roll.

[Broadsmile1987]

@PelletierPhysics that seems useless - what you get is a moving small gear, but you could achieve same output by reversing big gears rotation direction with another gear, and put the output on a big gear instead of a small :P This way You wouldn't overcomplicate things by dividing input into two gears plus making the second input move (imagine a steam machine sticked to the small gear, that's so stupid :D)

I can only see a room for a mathematical device, making a substraction: SG-BG=output

[PelletierPhysics]

@Broadsmile1987 This is a kinematics problem used in a physics class. You know two of of the angular velocities, you have to find the third, using relative velocities. It's makes the transition between the analysis of a rack and pinion and the analysis of a complete planetary gear set.

[cowboyvirus]

I am not familiar with the term "Hypocycloidal". It seems like a new term for an old device.

Also, in response to the question from BlondDogFunction

"What's the mechanical point of that? As in, what kind of steampunk device would use such a configuration?"

Such devices have been around long before 'modern' usage of steam. Not to patronize, but, their called clocks and watches buddy.

[PelletierPhysics]

@cowboyvirus I would say it's an old term for an old device: when Matthew Murray invented the hypocycloidal gear in 1802, he called it...hypocycloidal gear. In fact, the word is older than the device, because hypocycloid was already used in mathematics since a long time.

[BlindDogFulton]

What's the mechanical point of that? As in, what kind of steampunk device would use such a configuration?

[jasonrj8992]

what is the input? what is the output? what is causing the arm to rotate counterclockwise?

[nelsman]

Yes, seems that force is applied to both gears

[ryosvet]

Well isnt this the BASICof the BASIC of Rotary engine?

[kabivose]

@cowboyvirus Not wishing to patronise but I think you mean "they're called..." :-)

Yes, I'm English so my spelling is "patronise".

[SuperRafi1997]

small comment is lonely

[TomCollins519]

@Broadsmile1987 its not useless! a kitchen aid stand mixer would use it to have an attachment(attached to the small gear) go around mixing bowl while also rotating.

[Mrpsychotehpyro]

This WAS USED !

A parallel motion can be made from such a gear configuration by slight changes.

And that brings us to the hypoclycloidal pumping engine, a 19th century steam pump that uses this thing instead of a normal crank.

Just google the term...

[gushee44]

@ all youtube vid-nappers: oh you marvelous fools, who so readily criticize the output of others. and what do you bring to the world, but your bad additude? my guess is that the additude itself originates from the fact that you have nothing meaningful to put forth, it is a sort of grumpy jealousy, which only helps to illuminate the ultimate absence of value in your inherently meager minds! muahahahaha!!!!

[Broadsmile1987]

also, a bonus:

mathpuzzle (a dot) com/LoonyGearsAnimation.gif