[Al Skierkiewicz]

Archon,
Two speed transmissions are pretty common and have been used for some time. I became familiar with them on my washer a long time ago. Although the one you refer to appears to change gear ratio when the output shaft gets above a certain speed, my washer used the speed change on the input shaft to engage a centrifugal clutch to switch between agitate and spin. Centrifugal clutches had been used on garden tractors and tillers. When the engine RPM is below a certain point the engine shaft is disengaged from the output. Raise the engine RPM and internal weights force the clutch plates out and engage the engine shaft. (see the animation in Sanddrag's post.) In the first reference, I think the centrifugal part is the larger pulley on the left.