[EricH]

Originally Posted by asid61

Pneumatic cylinders usually, and in the old days I believe servos were more common than they are now.

Other way around, actually. FRC-legal servos are WEAK. I'd tell you young'uns when my team tried that, but I'd feel really old... and we went with pneumatics because of the servo response (and AM had a handy conversion kit for their Gen2 Shifter).

Did you know that before 2005, every team got two shifting gearboxes in the KOP?*

The thing is that most shifting gearboxes take force to shift. Servos have a hard time providing enough force to actually shift. Ball-shifters, I think are the exception for that, and a 3-speed ballshifter could really use a servo's "infinite" positioning, but as a general rule a short-throw small-bore cylinder per gearbox (and per gear change in the gearbox) say about a 1" throw 3/4" diameter unit in the old days, is by far preferable. Pancake cylinders are more common now because they're smaller, lighter, and don't take as much air. Servos are sluggish, and tend to need to be ganged together to shift. Ain't worth it.

You could also use an electrical solenoid actuator, but the power limits on those are even more restrictive than on servos.


*Two drill motor transmissions, to go with the drill motors generally used for drive. Shifting took a little machining, creativity, and luck during matches, but it was present. Before my time the full drill was included...