VersaPlanetary Gear Stripped on Climber

Hey guys,

Unfortunately our VersaPlanetary gear box (775 driven, duel stage each 10:1 total of 100:1) stripped some gears after about 15 climbs. We’ve seen teams climbing with with the versaplanetary but were wondering which gear reductions they were doing.
We are considering making it a 3 stage with the 2 5:1 kits and a 4:1 is this a good solution?

Thanks!

http://link.vex.com/vexpro/pdf/VersaPlanetary-LoadRatings

I would not recommend climbing with a 10:1 stage as your final output reduction. I would also not recommend 3 stages. You could do a 50:1 reduction in your planetary, and a 2:1 using VEXpro gears.

We are using a 775 pro through a 49:1 VP (7:1 & 7:1 stages) with a 28:12 #35 chain reduction.

We have seen a few failures of the 10:1 stages over the years in high torque applications so we opted for a third stage after the gearbox. Additionally we are supporting the output shaft with a bearing block to further prevent any damage or failures to the VP.

I’m not in favor of using a 10:1 ratio due to a 8 teeth sun gear which gets gammed easily.

I’ve done three stages to climb and it’s been fine, but I think a chain reduction and two stages is best for this game. Easy enough to integrate with a winch and no direct driving.

Agree, two stage much better and safer for the planetary.

How big is everyone’s spool. That’s another stage of gearing in effect. Our climber is 2 775s and 49/1 versaplanetaries. We use a 1 inch spool and drive it at about 75percent. 100% was too fast.

We had the 10:1 go bad on our duel stage also. The other gear was a 7:1.

We ended up replacing it with another 10:1 and used a 5:1 instead, but we’re planning on switching that to use two 7:1 for our next regional.

Replying from right next to Nolan, is there any reason the 3 stage would not be a good idea? The way our climber is currently, it may be harder to put a larger sprocket (larger than 15tooth). Our event is Thursday. Would it work to use a 3 stage, 4:1, 4:1 and 5:1 to get 80:1, then using 12 tooth to 15 tooth to get us the 100:1?

Yes, those stages are significantly stronger (about 5 times stronger) than the 10:1 stage.

As others suggested, the best thing to do would be to add a chain reduction between the gearbox and the climber, but you can get by with 3 stages.

Be careful to follow vexpros recommendation for max gear reduction for your motor selection. If you decide to run more reduction than recommended, you’ll have enough torque to deform the hex shaft, which just changes your failure point. Instead of burning up a motor, the hex shaft turns into a twizzler. Pick your poison :slight_smile:

See my above post :slight_smile:

You can use 3 stages, just be mindful of where the weak point is.

Would you possibly have room for a 18t & 36t hex sprocket to get you the 2:1 reduction you are looking for?

What are you running 100:1 for anyway? If you use the 12:15 reduction, you can get away with a 1.5" diameter pulley and a 50:1 VP. Reducing the pulley diameter is much easier (usually) than increasing reduction.

We are using a 1.5" spool diameter. Currently we are using 10:1, 10:1 and 12:12 (chain) with it.

Assuming you are using 1/2" diameter rope, you should be ok with the reduction that I suggested. Are you stalling the motor at any time during your climb (like when you hit the Davit)?

Never use the 10:1 as the last stage, we have broke the sun gear on these twice in the past two years with the climbs. We use a 70:1 with the 7:1 as the output and have seen no issues.

Just to be thorough, below is a snip of output stage strength versus hex shaft strength.

1 = same as 7075 hex shaft strength, > 1 is stronger than a 7075 hex shaft, < 1 is weaker than a 7075 hex shaft.

http://i46.photobucket.com/albums/f145/Infinity2718/VersaOutput_zpsfzoadcbj.jpg](http://s46.photobucket.com/user/Infinity2718/media/VersaOutput_zpsfzoadcbj.jpg.html)

From our intake rotation gearboxes last year, we destroyed enough gearboxes to valid these calculations. ::ouch::

*Note: These are calculations on the sun gear, it shows the 4:1 much stronger than the 5:1. However, we have found them to be equivalent. The 4:1 will fail in the ring gear about the same time as a 5:1 sun gear fails.

On question for y’all having issues running the 10:1 as the end (like in a 100:1) ratio. Are you running only one gearbox setup per mechanism. Or has some team who had two of those setup to a mechanism seen failure as well?

It’s in limited practice use only, but 229 has 2 775pros with 100:1 (two 10:1’s) gearboxes and a 1:1 chain ratio to the climber. No issues yet, will know for sure after TVR.

How heavy is your robot again? :smiley: