[GreenKeys] Pics of M15 Platen knob and/or crank / keytop question

[Jim Haynes]

I don't know about platen knobs.  That is what is shown on the patent
drawing, but I don't know if the knob shown in the parts book works
with the standard M15 cover.  Then not in the parts book but there is
also a handwheel or two, used with the "post office" style of cabinets,
one by W.U. and one by Teletype.  The handwheel sticks up through a slot
in the top of the cover.  One advantage of this is that the machines can
be put flush side by side without having to leave gaps in between for
the paper handles.

Spring cushion keytops are most common, and can be recognized by the
green color and the fact that they are springy to the touch.  I think
they were made by some third party and were made for typewriters as
well as Teletype.  The celluloid keytops are like old typewriters
used, and seem to have been preferred by Western Union.  They are
usually white background and black letters and maybe red for the FIGS
case characters; or some are black background with white letters.

I believe either style can be used on the same key levers.

There was once a third style called pneumatic keytops, but I've never
encountered those.  I assume they were air cushioned rather than
spring cushioned.

I've never seen a typewriter with spring cushion keytops, so maybe the
company was not very successful in selling them to anyone but Teletype.
I spoze one could go to a typewriter collecting museum or web site to
learn more.