[EricH]

Seeing as I haven't seen anybody answer this one yet...

A dog shifter has a slightly different setup. Two gears on the same shaft (one for high speed and one for low speed) have machined hubs that match the dog. The dog is able to slide a short distance between the gears, just enough to disengage one and engage the other (or vice-versa). I can't recall offhand exactly how it's set up to shift (I'd want to go read through the CAD and drawings again), but a pneumatic cylinder forces the dog into one gear or the other--servos are generally too weak for this particular application.


One other method of shifting--though it's generally used in custom transmissions--would be to simply slide the entire shaft over with the gears, but that involves some rather wide gears and some side impacts gear-gear--not exactly the most durable solution if you can find a better one.