Tule Trooper
As others have said earlier in this thread:
That gearbox was not meant to be shifted, while the bike is moving. So really, there are no chains or gears moving at that time, of shifting. No fingers should be chewed up.
Rather than transmission; I suppose (Hi - Lo Gearbox) would be a better name.
I had a Tule Trooper , Big Boy model, with a 7 or maybe it was an 8 horse engine; and I guarantee, in Hi, that thing would go Toooo fast for the brakes it had. In Lo it would pull a small trailer full of firewood up a mountain trail.
The Big Boy had a larger diameter rear wheel, larger frame, I'm not sure about the front wheel, maybe bigger.
Back to that gearbox: You didn't have to worry if you were in Hi or Lo. It would pull good and and speed in either.