IRI Teams with a spare P60 gearbox?

[Nemo]

I believe we have a 20:1 with a 550 mounted on it. If so I'll have our team toss it in with the rest of the stuff in case you need it.

[AllenGregoryIV]

Found it, it will be packed up with our stuff. Stop by our Pit Thursday or Friday.

[KrazyCarl92]

Thanks everyone! We will be sure to stop by you pits on Thursday or Friday, Allen.

Adam, the only complication I can think of with constructing a 20.4:1 from available parts is replacing the sun gear from the carrier to match the "wrong" size of the next stage, but it seems doable. Certainly wouldn't be a bad way to go if we had time and were stuck between a rock and a hard place. Anyone have experience with that on BB planetaries? See everyone in a few more days!

[AdamHeard]

Originally Posted by KrazyCarl92

Thanks everyone! We will be sure to stop by you pits on Thursday or Friday, Allen.

Adam, the only complication I can think of with constructing a 20.4:1 from available parts is replacing the sun gear from the carrier to match the "wrong" size of the next stage, but it seems doable. Certainly wouldn't be a bad way to go if we had time and were stuck between a rock and a hard place. Anyone have experience with that on BB planetaries? See everyone in a few more days!

Good Catch, with only single stage 4:1's you'd be missing the sun/carrier for a 4:1.

[KrazyCarl92]

Originally Posted by AdamHeard

Good Catch, with only single stage 4:1's you'd be missing the sun/carrier for a 4:1.

We may actually still have a good sun/carrier. The failure we see is a completely galled first stage reduction. The motor pinion and the gears it meshes with get destroyed. More than once this season I was able to combine the innards of multiple 16:1 gearboxes to make a new one. Of course by this point the motor was toast and we would need to attach a new pinion to a new motor anyway. The condition of the ring gear where it meshes with the first stage varies quite a bit though depending on how bad the galling got. The problem is that we can hardly notice it until the gearbox is completely seized.

One of our mentors looked at one of the failures and his immediate reaction was that there was no way the gears were cold-rolled, they must have been powder sintered because of the way there was metal powder everywhere in the gearbox. The cross section of the exposed inner surfaces of the gears also appears very non-uniform and grainy.

I've been doing research on other options for planetary gearboxes and we will likely be working with the VexPro Versa Planetaries in the future.

[MechEng83]

To transition between a 5:1 and 4:1 stage, you need a special carrier/sun gear that goes from the 5:1 planet spacing to the 4:1 sun gear size. There are actually 5 different carriers for the P60 gear box.
- 4:1 planets to output (required for last stage)
- 5:1 planets to output (required for last stage)
- 4:1 planets to 4:1 sun
- 5:1 planets to 5:1 sun
- 5:1 planets to 4:1 sun

http://banebots.com/c/P60P-CP

Incidentally, if you have mixed 4:1 and 5:1 stages, all the 5:1 stages must appear first in the gear box (nearest the motor), meaning you need to have an input motor with the 5:1 sun gear.

[KrazyCarl92]

I understand that the 5:1 stage requires a specific carrier plate (and planet gears), but are you saying that the 4:1 sun gear can not be pressed into every variety of carrier plate that accommodates the previous 5:1 stage? There's a different carrier plate for pressing in a 5:1 sun gear vs. a 4:1 sun gear? That would be absurd. Why not have the 5:1 sun gear and the 4:1 sun gear with the same press fit geometry?

[MechEng83]

Originally Posted by KrazyCarl92

I understand that the 5:1 stage requires a specific carrier plate (and planet gears), but are you saying that the 4:1 sun gear can not be pressed into every variety of carrier plate that accommodates the previous 5:1 stage? There's a different carrier plate for pressing in a 5:1 sun gear vs. a 4:1 sun gear? That would be absurd. Why not have the 5:1 sun gear and the 4:1 sun gear with the same press fit geometry?

Yes, I am saying that. I don't have access to the gearboxes until I get to our shop tonight to confirm, but I believe the carrier plates are different between the two. From what I recall, the sun gear in a carrier plate fits into a broached hole with the same number of teeth as the sun gear.