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# Determine the sign of torques for a planetary gear system

## Determine the sign of torques for a planetary gear system

(OP)
I am trying to calculate the power distribution of a planetary gear system,specifically a wolfrom system. I have posted a complete description of my problem here. Any help will be appreciated.

### RE: Determine the sign of torques for a planetary gear system

From the schematic shown in your link it appears you have a single input (P1) and a single output (P5). So the power at P5 would be the power at P1 minus any losses in the system. The type of compound epicyclic you describe is commonly used for large speed reduction ratio drives, and they tend to have fairly high mechanical losses.

Your schematic does not provide details such as the number of planet gears used or the positional constraints used for each member. So the load distribution between the (multiple?) planet gears cannot be determined.

### RE: Determine the sign of torques for a planetary gear system

(OP)
Thanks for the reply. My question is about the load distribution on the rings, not the planets.

### RE: Determine the sign of torques for a planetary gear system

I'd suggest that a diagram instead of a stick-figure schematic may help. I've been looking at the diagram and have no idea which parts are gears and which are housing and carriers.

http://mechanismsrobotics.asmedigitalcollection.as... for example.

It looks like users at Stackexchange have similar difficulty with understanding your schematic.

### RE: Determine the sign of torques for a planetary gear system

#### Quote (spapapan)

Thanks for the reply. My question is about the load distribution on the rings, not the planets

By "load distribution on the rings", I assume you mean the forces at the ring gear tooth contacts? These forces are applied by the planet gear teeth. The distribution of the planet gear tooth contacts around the circumference of the ring gear will depend on the mesh contact ratios, the number/spacing of planet gears, the profile/index accuracy of the gear teeth, and how the gear components are constrained. For example, a simple 3 planet epicyclic can have very good load sharing between the planets, but as the number of planets increase it gets more difficult to obtain even load sharing.

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