Neal,  We had a Harper Electric Piano at Ashorne Hall.  It was slim
like an ordinary piano, it's action was that of a Kuhl & Klatt, but
in this instance the pneumatic stack was underneath the key bed.
It contains the same pumping mechanism and semi expression system
as K&K.  The electric motor was indeed a 12-volt model, identical to
the 110-volt DC motor of the K&K, that is, a compound wound motor,
1300 rpm under load.  If the belt ever broke it would spin away to
infinity and explode.  The 12-volt motor on the Harper was the same
spec, it also had flat gauze wire brushes resting on the commutator.

As these machines came to this country as early as 1910, at a time
when there were no electrical mains, it would have been run on a set
of accumulators or wet acid cells which were common at that time.  The
motor had a small pulley, about 1.5" in diameter, and drove directly
onto the main crank shaft via a ten- or twelve-inch pulley.  If your
model Harper has mechanical shaft drive to the spool box then you will
have to get the pulleys just right to make the music sound sensible.

It will play at least for different types of rolls.  If your model has
a xylophone and mandolin then you will need the roll marked Kuhl & Klatt
or Harper.  Reliance and Pneuma rolls will also work but there is no
control of the xylophone and mandolin.

The valve chest is unusual in that the valves rock on a centre
fulcrum-like see-saw tipped by a push-rod pin which sits on a flat
lollypop-type strip of wood hinged over a rectangular shaped zephyr
skin pouch.  There is limited adjustment to the valve via an adjustable
threaded wire but they are usually corroded and tight to move.

I may have a picture of the piano somewhere, if I can locate it I'll
scan it and beam it to you.

Paul Camps

 [ MMDigest articles about this instrument are indexed at
 [ http://mmd.foxtail.com/Archives/KWIC/H/harper.html
 [ http://mmd.foxtail.com/Archives/KWIC/K/kuhl.html
 [ http://mmd.foxtail.com/Archives/KWIC/P/pneuma.html
 [ -- Robbie