Epicyclic formula

[anticz]

I've searched high and low and can't seem to find the formula for an epicyclic gear train where the carrier arm is the input, the ring is the output and there is no sun gear. Any ideas?

 

[MikeyP]

Erm...

Formula for what? Ratio? The carrier and ring rotate independently don't they? Or am I being particularly dim today?

M

--
Dr Michael F Platten

 

[hydtools]

No sun gear, no drive. Won't work, no ratio.

Ted

 

[anticz]

I guess I wasn't being clear in my description. Lets say I have a Carrier arm with one planet driving the annulus. How do I find the ratio between the carrier arm and the ring?

I tried using conventional formulas to find the ratio but I'm having difficulty because this would mean that none of the wheels are locked (if a sun existed it would be driven by the planet as well).

 

[hydtools]

Without a fixed sun gear the planet will not drive the outer ring. The planet has nothing to react against. Without the sun gear the ring may or may not just follow the planet and carrier arm.

Ted

 

[gearcutter]

Are you just talking about a pinion driving an internal gear?

Ron Volmershausen
Brunkerville Engineering
Newcastle Australia

http://www.aussieweb.com.au/email.aspx?id=1194181

 

[anticz]

Thank you Ted, I understand now. This is actually a small part of a larger more complex compound stage epicyclic train. I was trying to find a simple expression to isolate the ratio between these to gears but now I understand I have to step through the entire train to get this ratio. What a pain. Thanks again.

 

[hydtools]

This may be helpful:

http://www.efunda.com/designstandards/gears/gears_epicyclic_train.cfm

Ted