pic: GEAR & CHAIN IN TUBE 8WD

[Kevin Ainsworth]

This year for our climber we ran dual #25 chains in-tube, one within each chassis side rail. Since the chain was worked in only one direction, pulling the robot up the wall, there was only one slack side. We did contain the chain with the chassis rail on the slack side. The tensioned side of the chain is in open air, no containment. 200lbs of lifting force with four CIM's in low gear and no failures. It utilized a Vex 22 tooth sprocket on each end to transfer the drivetrain gearbox power via a PTO.

Image of in-tube climber chain run.
https://drive.google.com/open?id=0B6...jRVTzYxNGFjOWM

For a drive train where the chain is worked in both directions I would agree containing the chain on both sides could be beneficial and is good insurance. I wonder if anyone with in-tube chains has had issues with broken chain or chain that gets severely wedged between the sprocket and tube.

On the other side of the coin, we ran our drivetrain sprocket spacing at .015" under theoretical spacing this year (7.985" center to center sprocket spacing for 8" of chain length). There was a very large amount of slack so that the defenses didn't hit tensioned chain and damage it or knock if off the sprockets. Our run of chain was allowed to get pushed up past the chassis rails and the defenses would impact the chassis rails instead so therefore we never lost a chain this year.

[346CADmen]

For a drive train where the chain is worked in both directions I would agree containing the chain on both sides could be beneficial and is good insurance. I wonder if anyone with in-tube chains has had issues with broken chain or chain that gets severely wedged between the sprocket and tube.

346 ran chain in tube for our drive this year. Yes we did experience a broken chain and yes it is "difficult" to fix. Darn the ramparts.

While I was not able to view your design in detail, I would wonder if you considered assembly? It is difficult to assemble chain in tube with fixed centers. Guess I'll take a closer look to see how you overcome that issue.