There were different models around: "basket shifters" vs. "carriage shifters" (I've meanwhile polished my English typewriter terminology by visiting some relevant web resources). The model I was referring to was an "Adler" that came with the currency symbol "ℳ" for "Mark" (no "Reichsmark" or "DM") and was in use in our family until I got an electric typewriter around 1980. I wasn't able to find our "Adler" on the web thus far but it was very similiar to the "Erika" I've posted. It was a "carriage shifter", meaning the carriage was mechanically raised by the "Umschalttaste" while the levers stayed in place. I was quite surprised, how well I'm remembering the tactile feeling, when the "Feststelltaste" was snapping in after all those years and though I didn't give typing with this machine a thought during the past decades. I'm pretty sure, the blocking did only occur by mechanical deformation of the metal levers the "Umschalt" and the silvery button were attached to, but I vaguely remember to have seen the spring lock mechanism you mentioned, too, with other models.sedevidi wrote: ↑22 Apr 2021, 10:06AFAIK, "Umschalttaste" moves the typing levers up, "Feststelltaste" just pushes "Umschalttaste" AND activates a lock with a spring, leaving "Umschalttaste" in a down position. You had to push a bit "Umschalttaste" to release the lock and let the typing levers go back down.
The metal key is probably a "tab-stop" lever : push it down to set a tab-stop, pull it up to unset the tab-stop at the current position. Those tab stops are little metal tabs at each character position along the roller that stop the roller when you push it to the left. The "go-to-next-tab" key may be the red one on the right. That's the case on my 1967 typewriter.
I hardly remember any tab stop settings. At the time of writing with this device, I wasn't aware of such subtle writing techniques. I think there were some sliders at the carriage, that could be used for this purpose, but I would be very wrong, if the silvery button was usable for anything else than to unlock (lock?) the "Feststelltaste". Your model is apparently a much younger "basket shifter", so probably a few improvements did apply.
Ooh, and the red "Rücktransport" button (named "Rücktaste" with our "Adler") is just the backspace key. But it had to be pressed waaaaay farther down than temporary computer backspace keys, to achieve any effect.
