MisterKoenig
Such kind of gear trains probably use one idler gear which is connected to a mechanism that connects and seperates it after the crush. So this idler will change the direction of the transmission output shaft. The mechanism is probably a kind of spring system. This is what I can say...
Hi R1100S:
I guess it is good to look for some AGMA Standards. There are so many consideration issues; so, what type of application will you be doing and what speed are you seeking I think finding aswers to these questions might help you more.
Regards