pic: Banebot P60 Failure

[thefro526]

Originally Posted by Madison

What is the overall ratio? How heavy and long is the arm? Is it counterbalanced?

I'm just curious about the conditions prior to failure. We have a similar implementation using a BB 81:1 gearbox and have beat on it pretty hard over the last two days. We haven't experienced any problems yet, but if our implementation is similar to your, I may tear the gearbox apart and take a peak inside.

The overall ratio is approximately 819.2:1. The Banebot Transmission itself is a 256:1 ratio, and there is a 3.2:1 ratio after the transmission which drives the arm. The arms themselves are approximately 57" long with a 7lb load on the end. We also have some surgical tubing on the arm so it's effectively lifting a 1lb load at the end of the arm, and that load is being lifted by two RS775-18's through two 256:1 transmissions.

Originally Posted by Chris is me

Dustin,

Aren't you already slowing down the arm in software? All you need is another stage of chain reduction and you'll dramatically decrease the load on the gearbox, increase the output torque on the arm, and fix every problem you have.

We were planning on slowing the arm down in software if we found the need to. We may implement a 2nd reduction after the transmissions, but we'll need to see if this is physically possible with our system. A more likely solution is to swap the 15 tooth drive sprocket on the transmission to a 10 tooth drive sprocket which would give us an effective 4.8:1 ratio after the transmission.

I just want to say that they did not fail under "normal" use, they failed during a test in which I tried to get them to fail. I cycled our arm at the highest load point from 100% forward to 100% backwards a half dozen times before getting any sort of play in either transmission. One transmission failed, while the other was fine. (The drive sprocket for the arm was not tightened properly during re-assembly which appears to have caused one side to see more force than the other, but I'm not sure).

Note: This picture wasn't meant to start a discussion about our system, but to provide a visual record of a failed P60.