We spent two days trying to figure out why the planetary gearbox was binding up and this was the problem. The 3 pins need to be pressed flush with the plate, but as you can see they are almost 1/8" off.
Have you sent this information to [email protected]?
Aren responded very quickly to any issues we have experienced with our Versa planetaries.
I am sure they would appreciate your feedback on what you have seen with these pins.
There is obviously some opportunity for Vex to reduce manufacturing variation within their parts.
They just need to proper feedback and samples to communicate it.
Reminds me of the old Banebots P80 CIM gearbox from 07. Specifically the replacement carrier plates they sent out.
Was there any sort of shock loading present on your gearbox?
Last year Neutrino actuated an arm with a 100:1 gearbox through a 4:1 external reduction. Over time, the holes in the carrier plate elongated into an ellipsoidal shape causing the pins to loosen up and slowly pull out.
I can assure you that these did not start this way.
I can tell from one of the holes that it has been elongated and the pins lost their press fit. This is one of the two main failure modes for overload on a 10:1 plate. In all planetary gearboxes the pins that the planets rotate about see the highest load by a factor of 2.
I seem to remember your post from another thread where you were using this 100:1 with a 775. Is this correct?
What is the rest of your loading condition?
The carrier plate is the weak spot in the 10:1 design and we will try to increase its strength, but remember this gearbox has about 2x the load rating of the next closest competitor in this gearbox size and no one has a single stage 10:1 reduction stage.
Yes, this is from a 100:1 connected to a 775 in our design; it powers the winch for our catapult.
Keegan will have to verify this, but I believe this particular gearbox has not been under any shock load in its lifetime. In an earlier version of the design the gearbox did take the brunt of the force stopping our catapult, but that changed when we shattered a carrier plate in that gearbox (this came out of the replacement) and bent the frame supporting the entire winch, so this one should not have experienced that.
We where having the same issues with the gearboxes that move our arms.
We have disassembled them and pressed the pins back in with a arbor press a couple times now. the holes are starting to wear and the press fit is becoming looser. We have plans to disassemble our spare gearboxes and weld the pins in so they can’t migrate out.
Edit: I would like to note that we are using the gearboxes well outside the recommended load and ratio ratings. they are currently a 300:1 reduction. 2 stages of 10:1 and 1 stage of 3:1
Edit Edit: I would also like to add that knowing that we are using these gearboxes well above their designed specifications, I am shocked at how well they are taking the abuse we are throwing at them.
Is it possible to switch to a 3-stage configuration? Unless there’s a space issue, it should be as easy as adding a Ring gear and some longer screws.
Say a 775 - 5:1 - 5:1 - 4:1 ?
I’d say probably possible… but very tight space-wise. The wires to the motor are already making a bit of a radius against the inside of the frame where the assembly sits, but it might fit. We can check that tomorrow.
Yes, this gearbox has not been under any substantial load (relative to the last one). I clearly remember seeing these pins in the same position the first time I took the gearbox apart which was a couple weeks ago just to check everything before use. Paul knows more than I do, but this tranny was not under load before this happened…unless hooking it up to a shunt to test it is considered load.
What do you mean when you saying “hooking it up to a shunt?”
I just meant hooking it up to a battery and testing the motor under power. We call it the “shunt-o-matic” or shunt.