My team purchased the Rhino Tracks from Andy-Mark this year, but after driving with them, the pulleys (am-3298) have started to fall apart. The plastic is chipping around the bearing. Is anyone else having similar issues?
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there it is, thanks
Did you use locate when you assembled them? Because that looks. Exactly. Like. When a student used locate on our wheels. One year some got. On the plastic and the locktite eats. A. Component of the plastic. And they fall. Apart
We just had the same breakage today. We are checking for more signs of weakness. Did you have more than one break??
these wheels where assembled with 6 bolts, 3 per side. we followed the manufactures construction. I think that it may come from a combination of over-tightening of the the track, or the force of the robot slamming into the ground after crossing a defense. We have broken 5 of these wheels so far. Is this happening for anyone else?
-thank you for any info you can give
We haven’t done a lot of defense crossing yet. Today we were code testing when we found the broken piece. We weren’t even sure where it came from until I read your question. Keep us posted 
*update we found cracks on several wheels, some are in advanced stages but not broken yet. placement on the track was not a factor. we also do not believe it is a tension issue.
I agree with cmwilson13, it looks like you used superglue or Loctite on these.
Some plastics react badly (called crazing) to superglues (CAs in particular) and Loctite.
The bearings should be a slight press-fit into those pullys and should not need any glue. If they are a little loose, use a fender washer and spacer to keep them there.
no adhesives, only bolts. this is a very dense plastic, when it breaks it cracks it is a lot like obsidian, it forms very shiny surfaces
Just checked all that we have for our second bot and they have cracks in every one. Looks like it is from too tight of a fit with the bearing. Waiting for a reply from AndyMark.
This looks very very bad. Hopefully Andymark resolves this quick or there will be a lot of angry people with stationary robots.
My team hasn’t had an issue like this yet, and we attached a cinderblock and a lot of lead weights to our chassis and went over all the obstacles full-speed. So it’s definitely either over-tightening, or you guys just got a bad batch.
What position were the pulleys in when they failed?
The first one is the drive wheel, but we found them in seven of eight positions. We were doing basic driving when we found the broken piece. When we checked the pulleys we found cracks in all of them. We did some hard testing this afternoon and all of them are worse. All were installed per manufacturer’s instructions.