Quote:
Originally Posted by T^2
33 made this point a few times when talking about optimal acceleration ( here's a link). I second Adrian's suggestion of trying McMaster's brake/clutch lining. (Their thinnest is 1/8".) On another note, are you worried about deformation of the steel drum? It looks like your wall is around .050, and with the amount of force you're applying with the cylinder, I could imagine that the wall would get bowed out over the course of a season. |
Someone else also recommended the McMaster clutch material to us right as we were finishing up the design. Unfortunately we didn't end up getting a chance to figure out how to use it at this time, but would definitely investigate if there was ever a next time. Our main concern was we didn't have good ideas about how we would go about bonding the clutch material to a substrate, and we were also concerned about the tolerance stackup that this approach would cause. With the linkage geometry, we have only 10 thou of allowable wear in the shoe height (or tolerance error) before the angle goes from 10 degrees to 0, at which point the design stops working. This was one of the main risks that we wanted to investigate when building it. We were also concerned that if we had a wide range of lengths from the top of the shoe to the center axle, then under pressure the selector would be pushed into the center axle and bind, thus reducing the axial force that got turned into clutch friction.
We went with the thin wall for weight savings (and packaging). We had the luxury to spend a bit of time doing FEA on the drums and concluded that the steel drums have a factor of safety of about 3. It also helps that we are using a relatively higher strength steel. We haven't seen any issues with the drums deforming, but then again we haven't done much rigorous testing.
Quote:
Originally Posted by Bryce Paputa
How does the weight compare to a dog gear shifter?
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We haven't actually weighed the shifters (wasn't really one of our concerns), but we are pretty sure they are less than the 3 CIM dog shifters they replaced.