[pmangels17]

Originally Posted by chrisfl

So there are two different gear ratios both being driven at the same time. The gears on the output shaft spin freely and the dog moves back and forth to engage one of the output gears to the shaft?

Exactly. The difference between ball shifters and dog shifters is the method used to engage the gears to the output shaft. The dog is simple, just three teeth that engage the three teeth and/or cutouts on the dog gear. I am not exactly sure how the ball shifter works, I'm pretty sure it is the same idea but instead of a dog there are three ball bearings that slide in between the different gears. The ball shifter method is slimmer, but I like the dog shifter method because it seems simpler to me.

EDIT: If you're curious as to how they work, I think you can buy a ball shifter shaft with a couple of the matching gears for not terribly much money, and you can do a similar thing for a dog shifter shaft and the matching dog and dog gears.