Can Epicyclic Gearing Operate with No Fixed Axis?

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Homework Help Overview

The discussion revolves around the feasibility of using epicyclic gearing without a fixed axis, as suggested by a teacher. The original poster poses questions regarding the possibility of such a setup and the implications for the reduction ratio and torque.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants explore the concept of epicyclic gearing without a fixed axis, questioning the validity of this approach. They discuss the implications of torque and reduction ratios, noting that traditional methods may not apply.

Discussion Status

Participants are actively engaging with the original poster's questions, with some suggesting that the traditional reduction ratio may not be applicable in this scenario. There is an exploration of the mechanics involved, particularly regarding the interactions between the sun gear, ring gear, and planets.

Contextual Notes

There is an indication that the original poster is referencing a video for context, but specific details from that video are not included in the discussion. The conversation reflects uncertainty about the mechanics of epicyclic gearing when not fixed, and assumptions about torque and power output are being examined.

Cri85
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Homework Statement



The teacher said it is possible to use an epicyclic gearing with no axis fixed but nobody use the gearing like that. I watched this video:



at time 42s it's possible to watch it. I have 2 questions:

1) Is it possible to used the epicycloidal train with no axis fixed ?

2) If yes, what is the ratio of reduction ? is it dependent of the torque ?

Maybe if you have a link ?

Homework Equations



--

The Attempt at a Solution



I'm looking for this case, but each time the epicyclic gearing is used with one fixed axis.
 
Last edited:
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Cri85 said:
1) Is it possible to used the epicycloidal train with no axis fixed ?
I don't see an argument against it.

Cri85 said:
2) If yes, what is the ratio of reduction ? is it dependent of the torque ?
You have to consider all three rotations at the same time. Things like a ratio of reduction that consider only two do not make sense any more. That's probably the reason they are not used in that mode.
 
mfb said:
Things like a ratio of reduction that consider only two do not make sense any more.
I can set the input to the sun gear and the output to the ring gear (planets are free to turn like they want) ? Why there is no a ratio ?

In this case, it's possible to reduce a rotational velocity without give a torque on the support ?
 
Cri85 said:
(planets are free to turn like they want) ?
Then your output will not get any torque (neglecting friction). The free axis will rotate with the right speed to give zero output power.
 

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