Forgive me for the bad pictures, please. I was in a hurry.
A bit of backgroud –
Each of our collectors is raised and lowered by a motor/gearbox/timing belt setup. Each collector has two RS-775-12 motors, 2 70:1 Versaplanetary gearboxes and two 24:42 timing pulley reductions. The belt is 90 tooth, 9mm wide from Vex.
One of each of these assemblies (a motor, VP and timing belt) is on each side of the collector. The collector is 11 lbs.
Despite locating the pulleys at the distance suggested by this calculator – http://www.wcproducts.net/how-to-belts/ – there was a pretty notable amount of slack in the belts. Our first tests result in the belt ratcheting heavily.
We added a tensioning system and that seemed to be working well on our practice robot, however the same system isn’t working at all on our competition robot. Eventually, a belt on our practice robot broke.
So, basically, what gives? This is our first time using belts; I have some ideas about what we could have done better, but I’m a bit surprised with how much slack we had in the belts from the get go.
At this point, I think we’re going to switch to chain and see how that goes for us. We’re also using belts in the drive and those have been okay so far, but we haven’t used the drive very much. I’m nervous.