Klein-Adler with an extra trick

This cleaned-up little Klein-Adler has an extra lever compared to most others. The lever at the left is carriage-release, that lever at the right however is less usual. Couldn't find any other Klein-Adler that's pictured online (and many are!) with a lever there.

The lever actuates a prod at both ends of the carriage. The lever and mechanism is screwed into the ends of the paper-tray. This prod seems clearly designed to hold something, e.g. a ribbon-loop of ~8mm high.

Looking at this, the idea was that this could be a bichrome feature for the Adler. 

Adler thrust typewriters are a bit peculiar in that the ribbon and its 'toggle' is fixed to the base of the machine and not moved with the platen. That means that the platen moves up-down in front of the ribbon, ergo a ribbon needs to be the same width as the height of the type-slugs (i.e. very wide on this 3-bank). It also means that two-color ribbons are 'difficult'.

This lever and rods contraption looked like it could be a two-color typing mechanism, similar to how e.g. the Hammond implemented bichrome typing by simply lifting the red in front of the typing-line.

To test the hypothesis, a red imprint-strip was mocked-up with modern crafting "carbon paper". Had considered a length of 8mm ribbon, but that would soil the main ribbon and vice-versa. Carbon-paper actually is designed for exactly this type of 'manifolding' function.

The fitting was actually very tricky. It took a couple of tries to make a strip of the right length. The mechanism also needed some forming to make it clear all other parts and regain its bi-stable spring function. A long rod at the back functions as a holding-spring against the paper-tray ridge. This gives the whole thing stable down and up positions. In the up-position the strip is exactly on the typing-line - also blocking the view of what is typed: blind-typing. In the down-position it is clear and does not interfere with typing.

It still is a bit temperamental, prone to snagging on the type-guide - but as is clearly seen in below side-view the coloured strip moves with the platen and the wide ribbon is fixed to the machine-base.

It actually does work!

When the color-strip is in the up-position, the typing is of course blind. Am curious what type of strip was originally provided with this contraption. Also unsure if this was a factory-fitted feature or an aftermarket device. It matches the overall design and engineering-style of the machine and intricately fits the mechanism. It's also something Adler could/would have felt it needed to compete - by 1925 the Klein-Adler really was a bit outdated and lacking in features versus the competition. No bichrome for example :)

On the other hand, it's a bit fragile and convoluted. A machine on The Database only 10 removed from this one does not have this two-color function. On The Database is machine 315125 and this is 315115. Both machines actually have a Dutch florin symbol, but the '125 is a QWERTZ machine instead of QWERTY as this '115.

If a factory-option, then would've also expected more specimens to be visible online or some documentation. 

Quite possibly more information will turn up about this Adler two-color feature; something will have been written down somewhere sometime. For now, this Klein-Adler just has a neat trick; it can write in red too :-)