In Digest 961211 Andy LaTorre mentions the interposers that are thrust
between the punching ram and the individual punch heads in a production
perforator, which govern which punches are forced through the paper
traveling under the punching dies at any given rotation (cycle) of the
perforator.  He correctly says that the interposers are usually moved by
pneumatics or perhaps solenoids.  The QRS perforators use pneumatics.

I too visited Ed Freyer in Flemington three decades ago (and received the
same generous and patient treatment accorded Andy); but I don't recall
how his Acme was actuated in that regard, but I suppose it was
pneumatically.

The point of this is to state that the Wurlitzer perforators were excep-
tional in that the indexing rods that moved (or did not move) through the
holes punched in the master being read were connected directly to the
interposers, and that neither solenoids nor pneumatics were involved in
the system.  Each interposer extended horizontally as a long slender
shaft, the opposite end of which was the so-called indexing rod, which
rode on the face of the master cardboard, slipping horizontally into a
hole in the master when the master called for a punching.

Of course there was the necessary spring-work to retract the indexing rod
at the end of each perforator cycle so that the master could step
advance, just as there is in any perforator the necessary mechanism to
retract the paper punches from the paper being punched art the end of the
same cycle so that the roll paper can be step-advanced under the
perforating dies without tearing the paper.

If Andy does find his pictures, perhaps AMICA (who already, as mentioned,
did a large piece on perforators) or MBSI would be interested in
publishing them, with or without and accompanying text (Andy?).  That way
lots of us would have the pictures, which I would like to see.  If not
that, perhaps Don Rand would be an appropriate recipient.

Matthew Caulfield