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Animating the second stage of a geartrain
james_aguilar160
Member Posts: 50 ✭
Hi, I'm making a two-stage planetary gearbox. In real life this thing works as expected but I'm a little stumped on getting it to animate as expected!
https://cad.onshape.com/documents/696ed47dd6e84f881da8c56c/w/a7db5e51e522e9ce3267da1e/e/af4efb9a20716f279ac14f39?renderMode=0&uiState=670b4060cde83810b20eba9e
So, to my understanding, planetary gear box with 33 outer teeth and 9 sun teeth gives ((33+9)/9)= 4.667:1 reduction. I have defined various mates, but for the purpose of this question I think PC1-Ground, Sun-Ground, and PC2-PC1Pinion are the important bits.
Every time the pinion rotates 360 degrees, the first planet carrier should rotate a little less than a quarter of the way around. This is expressed by gear 1, and seems to work okay based on the animation.
Now, the same relationship applies between the second sun/pinion gear and the second planet carrier. What I'm not quite clear on is how to express that. I could define the revolute of the second carrier relative to the ground, but: 1. I don't have a convenient mate connector and 2. it feels like I should be able to make it work the way I'm doing it.
I'm hoping someone can help me understand where my wires got crossed here. Is there a sensible way to define a "gear 3" given the mates I have set up? If not, how would you mate up this set of parts to get life-like animation?
Comments
For anyone following in my footsteps, I managed to get this working here:
https://cad.onshape.com/documents/e1ab8df4bfddae632ed05776/w/8252044a08b1f76aad48388a/e/3657d14025d34633a0e80e10?renderMode=0&uiState=670f27f3dbcc074d8b64a236
(To try it out, animate "Pinion Around Motor".)
Instead of trying to revolute the upper planet carrier around the lower, I used a cylindrical mate with the motor. Then, I removed the Z degree of freedom by doing a planar mate with the carrier below. Then I could gear the second carrier like so:
And the planets could be geared to the second carrier's rotation rate based on the number of teeth in the planet compared to the number of teeth in the outer gear.