I've mentioned this previously but seem compelled to do it again.
About 25 years ago I sold a 1913 Chickering Stoddard Ampico upright
to Frank Adams.  It had a long pump across the bottom of the piano,
with the hinges at the outward ends and a movable center board,
making four exhausters in all.  It was driven with a round flat belt
to a large pulley on the pump, then a second reduction to a flat belt
that drove the two connecting rods. The pump turned quite slowly.

The tracker bar was as any common Stoddard Ampico.  The expression
was accomplished by three different sized pistons ganged together on
a small threaded rod, connected by a spring to a crescendo pneumatic
that had a threaded screw to set the zero adjustment.  The pneumatic
had two speeds as controlled by another pneumatic operating a rotating
valve with two different sized bleeds.

On-off switch was a two-button wall light switch with a hole drilled
in one of the buttons and a rod threaded into it.  Tempo and Rewind
were controlled with one lever.

If anyone out there knows where Frank sold the piano, I'd sure
appreciate knowing.

Thanks,

Tom Binnall

P.S.: Art-Echo used an Ampico style pump with a separate and very
strange spill arrangement.