Rhino tread snapping?

[DonRotolo]

Originally Posted by microbuns

(I apologize for how huge they are).

Don't. HUGE photos are exactly what is called for in this instance; it makes what happened easier to see.

Are all 3 of those images the same 'end' of the belt, or are we seeing different ends in images 1 and 3? I suspect the latter but want to hear it from you.

[scca229]

Originally Posted by DonRotolo

Don't. HUGE photos are exactly what is called for in this instance; it makes what happened easier to see.

Are all 3 of those images the same 'end' of the belt, or are we seeing different ends in images 1 and 3? I suspect the latter but want to hear it from you.

I see the same thing you do I suspect. 1 & 2 look to be the same end of the belt, just flipped over. 3 looks to be the other end as it looks to have the missing "chunk" from 1 & 2.

[microbuns]

Originally Posted by scca229

I see the same thing you do I suspect. 1 & 2 look to be the same end of the belt, just flipped over. 3 looks to be the other end as it looks to have the missing "chunk" from 1 & 2.

Yes, I can confirm this. Should have labelled the pics when I put them up - sorry about that!

[DonRotolo]

OK, Thanks.

From the markings I see on the central "lumps" of the clear side of the belt, I theorize that the belt slid sideways on the wheels, so when the drivetrain was powered up they rode up onto the wheels. This stretched the belt to catastrophic failure. I am thinking that an under-tensioned belt could do this.

I am not trying to cast apsersions or 'blame'; just hypothesizing (= guessing) as to how this might have happened.

Anyone else have a theory?

[Richard Wallace]

Don, I think your theory is correct.

Our experience (this season only) with tracks is that low tension can cause the belt to slip off the side of the pulley when the robot is pushed sideways while moving forward or backward. This subsequently increases tension, either locking that side of the drivetrain if you are lucky (as we were), or causing extreme stress on the misaligned belt if you are not. The latter case happened here, I think.

We've been checking belt tension between matches. We also modified our turnbuckles to include lock washers and jam nuts.

[cbale2000]

Another failure mode to consider when talking about side-loading on belts is belt impingement on the frame itself. On many of our tank tread robots in years past, the belt could come partially out of alignment, sticking out past the bottom of the frame during a T-bone, but afterwords could self-correct; however if the frame had a sharp edge on the bottom when pushing occurred and the driver attempts to drive, the result can start enough of a cut in the tread that it compromises the entire belt and cause it to fail in a similar method to the previously posted pictures.

In addition to proper tensioning, I recommend checking the bottoms of the drive plates for sharp edges and clean up what you can.