I was interested in the arrangement mentioned by Brian Thornton
regarding concert hall concert grand motor arrangements.  I retrofitted
a gutted concert Chickering a few years ago too, and noticed that there
had once been mounted three motors.  Two ac motors, and one dc motor.
The two ac motors I learned, were shived together, and then a large
motor pulley drove the pump at about double speed.  The dc motor was
used for those stages that had dc power.

I got around the double motor arrangement by taking a later model "B"
motor to the motor shop and having them wind it in such a way that it
doubled its power so I could use the oversize pulley.  But if your
crankrods in the pump are maple, they will not stand up under that
pressure very long.  The rods started to knock after two weeks of
playing.  So before I went to the expense of replacing everything will
ball bearings, I made another set of wooden rods from the highest
quality delignite pin plank material, and I made them as extra wide as
I could possibly get in.  It was a great choice.  And to this day, I am
told that piano is "peeling the wallpaper off the walls."

Craig B.¶
craig_brougher@msn.com