Quote:
Originally Posted by Ben Piecuch
As Cliff pointed out, there are a few two and three speed designs listed in the whitepapers section.
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You forgot the four-speed.
Historically, transmissions have been shifted one of three ways:
1) Pneumatic cylinders. These are relatively cheap, easy to install in most cases, and they have enough oomph to them to get the gears shifted. Problem is, that requires a pneumatics system, which adds both weight and complexity to the robot.
2) Servos. Servos are cheaper still, can be put in a middle position (good for shifting the DeWalt three-speed transmissions) and don't require any added systems, but they sometimes don't have enough force to do the job. And your programmer will have to do some fiddling to find the right value to use for each gear.
3) Motors. Teams will use a kit motor (the Globe motor seems to be a common choice) to turn a rod to shift the gears. This is sometimes preferable over pneumatics, but they may be a little slower to shift, and you have to add feedback of some other sort (encoders, switches, etc.) to make sure the motor's keeping the robot in gear. Of the three, this is generally the least common in my experience.
Each has their highs and lows, which only you can evaluate as it pertains to your design. Hope it helps!