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Help with Planetary Gear Arrangement

Help with Planetary Gear Arrangement

Help with Planetary Gear Arrangement

(OP)
Hi all,

Need help with a Gear Train described below. A rough sketch is attached.

1)We have a Round Plate above which there is a 88 Teeth Gear (Gear A). Both have their own drive and the ratio is 1:4. For every 1 turn of the plate, the Gear A rotates 4 times. They both rotate in the same clockwise direction.

2)On the plate is mounted a Gear B which meshes with the 88 Tooth Gear A.

I want it such that for every 1 rotation of the Plate, the Gear B rotates 18 times.

I am unable to figure out the no. of Teeth for Gear B, and would be grateful for any help with the formula/calculation.
If required, I can change the ratio between the Plate and the Gear A and/or the No. of Teeth on Gear A.

RE: Help with Planetary Gear Arrangement

msb101,

That's not really a planetary gear system.

If gear B rotates 18 times for each rotation of the plate, it rotates 18/4 times for each rotation of gear A. You need 88teeth/18×4=19.6teeth, approximately. It will rotate in the opposite direction. If you want to turn exactly 18 times per turn of the plate, you need gears with 90 teeth and 20 teeth, respectively.

This is not very complicated.

--
JHG

RE: Help with Planetary Gear Arrangement

(OP)
Hi,

Thanks for your reply. We did a simulation in solidworks with the 90-20 Teeth Combination and it didn't work. The number of rotations of Gear B don't remain constant with every rotation of the plate.

RE: Help with Planetary Gear Arrangement

msb101,

If you have a gear train of any kind with round gears in constant mesh, the output gear should rotate at a constant rate. If your output is varying, something else is moving.

--
JHG

RE: Help with Planetary Gear Arrangement

(OP)
We did a simple simulation in solidworks and everything is fixed, so nothing else is moving.
It gives us approx. 13.5 revolutions

RE: Help with Planetary Gear Arrangement

(OP)
Hi,

What worked is 90-15 combination. It gives us exact 18. Thanks.

RE: Help with Planetary Gear Arrangement

Your description leads to believe, that the revolutions of the gear B are measured relative to same thing as the revolutions of the plate, e.g. a housing in which all the items rotate. The combination 90-15 is correct relative to the plate, i.e. for every one revolution of the plate relative to the housing the gear B makes 18 revolutions relative to the plate, and 17 revolutions relative to the housing.

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