What's the formula for planet RPM in an epicyclic gear.

[anticz]

Hello,

I'm designing a planet gear with an output of 4:1. Here are the details; Sun = 24 teeth, Planet = 24 teeth, Ring = 72 teeth. The sun is the input, planet carrier is the output. My question is what is the formula for finding the output of the planets gears themselves? For example, for every 4 revoltions of the sun I will get 1 revolution of the planet carrier arm, but how many revolutions will I get from the planet gear itself?

 

[Matt51]

Overall ratio = (72+24)/24 = 4:1.
Assembly = (72+24)/N where N = number of planets, so ok for 3 or 4 planets.

RPM of planet gear relative to carrier =(-Zr/Zp) or -3, where Z is teeth and n is rpm. Relative to ground is (1-Zr/Zp), or -2.

 

[anticz]

Thank you, exactly what I needed. Simulation works perfectly.