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Versa Planetary v2 (3:1) Planet Gear Seizing
Has anyone else had any problems with any of the planet gears from their Versa Planetary v2 transmissions seizing up in the middle of running a motor?
This has happened twice this week on seperate shooter prototype desings. One had two 4" Colsons on a shaft, and the other had eight 4" colsons on the shaft. Both were using 775 pros. We ran the wheels at the speed we wanted multiple times to test shooting consistency with the PID, and after a while, the wheel completely locked up while the wheel is in motion and causes a sudden stop. Both times this has happened, we opened the transmissions and found that exactly one of the planet gears got completely stuck on its pinion and we cannot get it unstuck. This has only happened on 3:1 v2 transmissions so far. We're wondering if this is a manufacturing flaw that isn't just happening to us. |
Re: Versa Planetary v2 (3:1) Planet Gear Seizing
I just swapped a 3:1 today with same issue, one gear stuck. We didn't even get any runtime on it. Hope we don't have anymore issues...
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Re: Versa Planetary v2 (3:1) Planet Gear Seizing
I haven't used 3:1 this year, but I have a few questions/suggestions. Did you properly grease the gearboxes? Did you support the shaft well (i.e. no radial load on the shaft)? Was there any axial load away from the VP? I have heard that all three of these can cause failures.
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Re: Versa Planetary v2 (3:1) Planet Gear Seizing
Also when were the 3:1 stages purchased.
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Re: Versa Planetary v2 (3:1) Planet Gear Seizing
We've been having some issues with VersaPlanteries this year. What fixed most of the binding was taking 2 planet gears and flipping them over then reinstalling them. That and letting the gearboxes burn in at a low speed for a few minutes.
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Re: Versa Planetary v2 (3:1) Planet Gear Seizing
The planet gears should be the same between the V1 and V2 models. Just the case / mounting changed.
Could you post pictures of your seized planet stage? |
Re: Versa Planetary v2 (3:1) Planet Gear Seizing
Also I'd suggest (if you haven't already) grease the shafts that planet gears themselves spin on instead of just where the gears mesh.
The gear's may be generating heat, swelling, and seizing up. |
Re: Versa Planetary v2 (3:1) Planet Gear Seizing
We are running the same 3:1 ratio in the v1 gearboxs with 775 pros without issue, we used the very same gearboxes all 2016 season(5 competitions) with regular 775's and only had one set screw come loose other than that no problems, we haven't bought any of the V2 versaplanterary's yet
EDIT: we did grease them heavily |
Re: Versa Planetary v2 (3:1) Planet Gear Seizing
MORE LUBE!!!!!
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Re: Versa Planetary v2 (3:1) Planet Gear Seizing
Check that the pins on the carrier plate haven't moved. We had trouble with them popping out slightly and seizing in 2015 and ended up having to weld them in (Pretty sure VexPro suggested this when we contacted them). We used the v1's, but the v2's still don't have welded pins.
This was under pretty high torque though, which it sounds like yours aren't. Just a suggestion. |
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Re: Versa Planetary v2 (3:1) Planet Gear Seizing
Built a few planetary gear boxes today and the motor plate was so tight and seemed to force the shaft off center. Runhinged them at full speed for a little while helped. So did extra lithium grease.
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Re: Versa Planetary v2 (3:1) Planet Gear Seizing
We experienced similar issues today. BRAND NEW 3:1 stage.
1x775 into a 3:1, single stage VP. Just as you are describing, a single planet began to seize on its pin. The seized planet was even swapped for used planet gear from 2016 with the exact same results. The transmission almost immediately began to seize from the same pin. The gearbox was reassembled multiple times by different people and was properly greased. Maybe it's time to explore needle bearings... |
Re: Versa Planetary v2 (3:1) Planet Gear Seizing
We're running a pair 775 pros through a Versaplanetary v2 3:1 reduction for a week or so now and have had no problem with it.
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Re: Versa Planetary v2 (3:1) Planet Gear Seizing
We had a problem with a brand new 3:1 not fitting into the ring gear correctly. We had bought two so we tried the other one without incident. Swapped them out and the problem stayed with 3:1 not the ring.
I contacted VEX and they shipped a new one out ASAP and requested the bad one be returned (on their dime). New one works perfect. Please stress to your students that if they don't go together easy and can be hand turned inside the ring gear, they may have an out of spec 3:1. Contact VEX if you get some bad ones. Great folks and great service. |
Re: Versa Planetary v2 (3:1) Planet Gear Seizing
We have been having issues with 3:1 reductions as well.
One of ours was obviously made out of spec (one gear couldn't move at all, couldn't be removed from shaft) and the other was having binding issues. We just used 4:1s, and they worked fine IIRC. |
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Re: Versa Planetary v2 (3:1) Planet Gear Seizing
Had the same problem with a new 3 to 1 sent back to vexing haven't heard back except to send us a new one reading this I should test all the 3-1s I have I guess
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Re: Versa Planetary v2 (3:1) Planet Gear Seizing
I'll start by saying if you think you have a problem, call (or email, prosupport@vexrobotics.com) us.
We have had a few reported cases of 3:1 gear kits having seized gears or being a very tight fit in the ring gear. In most cases of a tight fitting 3:1 gear kit it's a combination of the gear kit being toward the high side of the tolerance and the anodizing on the ring gear being a little thicker. This is easily solved with a run in. I've seen two cases of gears seizing on pins. One was from a bur on the bore of the gear. The other was from a crooked pin on the carrier. I've yet to see any cases where the pin or bore on the gear were out of tolerance. In some reported cases we've been able to fix the issue and in others we've replaced the gear kit. Here are a couple recommendations I have if you have a tight fitting 3:1 gear kit: 1) Make sure there's no dirt or large debris on the gear teeth. 2) Run the gearbox in, lubricated, for 30-60 minutes. All gearboxes need to be run in at some point. In some cases (ex: the transmission in your car) they do the run in at the factory. However, due to the modular nature of the VersaPlanetary we do not have that luxury. Note: Lubricated does not mean packed full of grease. You can over lubricate a gearbox. |
Re: Versa Planetary v2 (3:1) Planet Gear Seizing
Somewhat on-topic here...
A question for the collective knowledge pool: How much lithium grease is too much / how much is too little? (Keeping in mind the v2 manual uses the term "liberal" -- some students will want to drown the gearbox, others will go the opposite route.) We had a borrowed VP last year that was pre-greased (rookie year) and went out and invested in several this year, so we're looking to do it right. |
Re: Versa Planetary v2 (3:1) Planet Gear Seizing
Ed,
Where were the seizes taking place? I assume a planet gear was locking up on the carrier plate pin. As mentioned, lube is crucial, not only between the planets and ring but also between the planets and pins. One other thing to check is if the pins are perpendicular to the plate. Any misalignment will eat the VP alive. |
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I like to paint the grease onto the outer edges of the planet gears and spin it around, then add more and spin, etc until every surface has some visible grease on it. Then a touch more and assemble it. It's not that easy to over-grease a gearbox. |
Re: Versa Planetary v2 (3:1) Planet Gear Seizing
We have had the same issue with a 4:1 with proper lubrication. Found a burr on the peg and gear of one of the planetary gears
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Re: Versa Planetary v2 (3:1) Planet Gear Seizing
A point that I observe many people missing when greasing VP gearboxes: every planet gear should be taken off its shaft and have the shaft/bore in the gear greased and have the bottom face of the gear greased. Packing the inside of the transmission with grease isn't enough to get grease where it needs to be!
I can easily imagine not greasing these areas leading to a seized transmission. |
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