[RogerR]

so far as i know, there are two ways to shift the dog using a pneumatic cylinder: internally, and externally.

when the internal option is used, a pin connects the dog to a rod that runs through the center of the axle. the rod is connected to the cylinder through an assembly that allows the rod to spin with the axle, without spinning the cylinder.

the external option is simpler; it is simply a stationary 'claw' (for lack of a better term) that rides in a groove cut into the circumference of the dog. the pneumatic attaches directly to the 'claw' and when it is extended or retracted, the 'claw' forces the dog into the appropriate gear.

[edit] ach! beaten twice!![/edit]