18 Z 1/2"

The Torpedo sprockets come in different
flavors. The 3SP (Triplex/Dreigang) I have are
19T, the Duomatic is 20T.

The letter "Z" is the German "Zahn" for
"tooth", plain and simple.

The Duomatic has a sprocket, or a

Zahnkranz 1/2 x 1/8" aufsteckbar

"aufsteckbar" is "attachable" so the inches
probably refers to something that has to do
with that.

It also says

(s. Liste Nr. 196.6/8)

anyone has that one lying around?

--
underground experts united
http://user.it.uu.se/~embe8573