I've spent way too much time drawing this diagram...
Like most things on a typewriter, these simple rubber feet are actually ridiculously complex and specialised parts.
This construction ensures that vibrations from the inner frame (where the typing happens) are not carried to the metal outer shell or to the surface the typewriter is sitting on.
@draemmli so the red part is the rubber? It should be shaded in both diagonals in this case *smart ass mode off* ;-)
@petrisch Interesting! Why?
Because it's the part of the drawing we're interested in?
@draemmli
Ah no its indicating the material:
https://de.wikipedia.org/wiki/Schraffur#Schraffuren_in_technischen_Zeichnungen