[pianotech] Player question

Chuck Behm behmpiano at gmail.com
Tue Aug 10 12:19:07 MDT 2010


John  - The bellows with gussets are pumping bellows. You'll notice that
they are sprung to be closed all the time. When you push on the pedals, you
open the bellows, pulling air from the reservoir bellow. Then, when you let
back on the pedals, the spring closes the bellows. The flap valve on the
inside closes, and the flap valve on the outside opens, allowing the release
of air.  If you don't have gussets, the fabric of the bellows cloth will be
likely to pop out as well.

The reservoir bellows is sprung to be open. As the air is drawn out by the
pumping bellows, it collapses, sucking the fabric of the bellows inward. If
the pedals are pumped less vigorously, the bellows begin to be opened by the
inner springs, pulling air from the chest of the player action overhead. The
fabric at no time is likely to pop out.

This is just my impression of how the mechanism works. I know that not
replacing the gusset material is not a good idea, in that I tried that
once.  Chuck Behm
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