Quote:
Originally posted by Antonio
I've heard from some of you that change gears refer to the Bosch gearbox, do guys mind telling me what that is, since my team is interested in switching gears for this years competition  Thanks!
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You know how hand drills have a little switch that makes it spin slower but more torque? That's what teams use in the drill motors to shift gears. What you couldn't see in the picture of the drill transmission, is a silver strip of metal that you can move back and forth to select either high gear or low gear. Teams usually use a servo motor for each drill transmission to move that metal strip to switch gears. I know some teams use pneumatics to do that as well.
There are planetary gears inside the drill transmission. The metal strip engage one of the ring gears that slide from one stage of the planetary gears to another. In High gear, that ring gear is in a position where it lock one stage of planetary gears together so that it act like as if that stage doesn't exist. When you switch to lower gear, the ring gear slide out and unlock that stage, adding further reduction to the transmission causing the output shaft to spin with a slower rpm, but higher torque.
Of course, this isn't the only way to do this. There were different transmissions I've seen in the past years, and the technokat's servo transmission is only one of them. There are other ways like
having another set of wheels on your robot with a different gear ratio, and you lower those wheels when you want a different speed/torque combination. I've seen this on 131's 2000 bot, and 258's 2002 bot. Changing wheels size is also a mean of switching gear ratio too.
There are also ones where there are two set of gears on the same shaft, and only one set is engaged at a time, and you use pneumatics to engage the other set of gears for a different ratio. I've seen this on 67's 2001 bot, and 45, 60 and 254's 2002 bot last year.
Then there were other teams who lower another set of drive train with a lower gear ratio, like 111 and 810 last year I believe.
But most teams use the servos to switch gears on the drill transmissions because its fairly easy to do. You just got to figure out a good servo mount on top of the transmissions, and make sure the linkage between the sergo output arm and the metal strip is good enough.