Steve, back-pedal (coaster) brakes are just deceptively tiny drum brakes actuated with a threaded barrel mechanism instead of a cam; to me, the actuating mechanism looks and feels a lot like the guts of an impact wrench.
Sheldon Brown is probably the best resource on coaster-brake hubs for both identification and repair:
"link":http://www.sheldonbrown.com/coaster-brakes.html
I am now off to be further distracted by that awesome Zundapp site.