Quote:
Originally Posted by Tom Line
I'm looking forward to trying the ball shifters this off-season. We usually don't use shifting drivetrains because of weight, but that may change now. I would absolutely LOVE it if Vex can look into supplying a kit that allows fast reliable shifting without pneumatics. In fact, with a little innovation, it's not impossible for the same kit to work on the supershifters as well. I've seen a number of solutions. The most elegant I saw was a single window motor with spring loaded arms (Hot in 2012). The servos are simply not powerful enough to shift under load. I've seen very few teams use them for exactly that reason. We plan on putting the ball shifters on our robot for the off-season to test them out, and will probably look at a solution at that time (we don't have pneumatics on this year's bot). There was a fellow at MARC last year with a really nice sliding arm linkage made out of lexan that was along the same lines - just bolt on a window motor and go.
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I originally sent this suggestion via PM to Adam, thinking it was just a possible solution to specific issue, not thinking it was really relevant to the general VexPro product recommendation topic. However, after reading your post I and Adam's other post, I think it might be on topic.
Electric Solenoid Actuators are legal for use in FRC since last season. See R32 for the specs and R70 for the maximum output of your Solenoid Breakout (alternatively, you can use relays). I speculate that the primary reason for this rule change was to facilitate shifting without pneumatics. I expected to see some teams use them or Andy Mark/VexPro to make a electric solenoid shifter kit. However, I haven't seen anything yet, maybe it is something they will develop this off-season (I dont know what the market is like for non-pneumatic shifters and the ball shifters are new this year).
There are many design considerations for electric solenoids including:
-Push vs. pull (this determines your default gear ratio)
-Return spring (to keep you in default)
-Solenoid package and mounting bracket
-Force vs. stroke (it varies, look for it in specs) enough to shift
-Wattage
It would be nice if one of the vendors engineered a nice solution for everyone to use.