What Makes The Gear Go?

Hi everyone,

I like many other are trying to model gears and simulate their physics. I found the perfect example within the “physics test files”. The file is called 2_Gears_simulation.blend. Eventually I’d like to model a planetary setup but I have no idea what makes the initial gear turn. How does it work? I’ve found the rotation constraints and the physics properties but nothing that tells “Cylinder” to turn. There’s no script or IPO or anything else I can find. Any ideas?



its angular velocity :rolleyes: in the game logic:eyebrowlift: im using lots of emoticonss because im cool :cool:


oh SNAP! How’d I miss that one. I was sure I went through every parameter in Blender looking for something like that. Thanks for the quick reply! :smiley:

It’s an interesting demo of the physics but it’s more about collisions than the actual mechanics of a gear train. It’s none of my business but you wouldn’t seriously attempt to use blender to model the mechanical efficiency of a gear train would you? In real life even the noise a gear train makes can prompt engineers to seek improvements.

Just use arithmetic to set the rotation of successive cogs. By all means study the engineering and use blender to represent the physics but don’t attempt to model it in the sense that anything significant can be discovered about mechanics by using blender.

Ahem Mr. Equip

I second that

Ok so maybe model isn’t the right term. I like the idea of setting up the gears to collide as it better shows the gears actually meshing with each other. I’ve seen a few tutorials where the math is done to change the speed at which the gears turn to simulate meshing, but I think it looks funny that the gears turn without really touching each other.

All I’m trying to do is generate an animation of a planetary gear set. Visual aide only. No REAL physics, engineering, or modelling of any kind. The ultimate goal is to add some buttons so during the “game” the power input can be selected (sun, planet, or ring) to visually show the difference in gear speed and ratios.

Nothing too crazy, just a game. Thanks for all the info.


Also, now that the BGE has some support for concave rigid bodies, you could make each gear out of a single object rather than each tooth being a box with compound collision. That also makes it easier to have those sloped teeth that makes gears have a much easier time meshing. Just a thought.