Music Trade Review

Music Trade Review -- © mbsi.org, arcade-museum.com -- digitized with support from namm.org
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THE MUSIC TRADE REVIEW
Wind Chest
The arrangement and design of the
Wind-Chest and the Pneumatics, and
their relation to the action of the piano,
provides a simple mechanism which
works with GOOD POWER and
SPEED, is very compact so as to go into
a comparatively small case and which is
readily accessible for adjustment or re-
pair.
The Wind-Chests (A) extend entirely
across the front of the piano action in
front of the vertical stickers (B) which
transmit the upward movements of the
rear ends of the keys (C) to the whip-
pens (D) which operate the hammers.
The several Wind-Chests (A) are in
communication with each other at their
ends and are in communication with the
Pumper by which a partial vacuum is
maintained in said chests. At the backs
of the Wind-Chests are located the Pneu-
matics (E and F), those in one row be-
ing staggered relatively to those in the
next row so as to bring the center of
each Pneumatic in line with one of the
stickers (B).
For each Pneumatic there is a set of
valves (G and H) which open communi-
cation from the atmosphere or from the
Wind-Chest respectively to the passage
(J) leading to the Pneumatic; each set of
valves being controlled by a diaphragm
(K), the upper side of which is exposed
within the Wind-Chest and the lower side
is exposed to a passage (L) which com-
municates through tubing with opening
in Tracker Bar. The passage (L) also
communicates through a bleed-hole (M)
with the Wind-Chest. Thus when an
opening in the Tracker Bar registers
with an opening in the note sheet, air is
admitted to the passage (L), the dia-
phragm (K) is moved upward, carrying
with it the button and stem (N) and
shutting off communication with the at-
mosphere and opening communication of
the pneumatic with the Wind-Chest so as
to collapse the pneumatic.
When the opening in the Tracker Bar
is covered there is a gradual restoration
of the balance on opposite sides of the
diaphragm by the passage of air through
the bleed-hole and the valve is lowered
and the pneumatic expanded to its posi-
tion of rest. In other words, when the
air ceases to enter the channel leading
from Tracker Bar, the air in the dia-
phragm chamber is exhausted through
bleed-hole, valve H seats, valve G opens
and the pneumatic opens, ready for an-
other operation.
The pneumatics are provided each with
an arm (O) attached at an angle to the
movable member (F) near the hinge end
of the pneumatic. This arm is adjust-
able angularly, being pivoted on the
block, through which passes an adjust-
ing screw (S) the end of which bears
against a lug (T) on the arm and the
head is ACCESSIBLE FROM THE
FRONT by a long-bladed screwdriver.
This screw is commonly known as the
"lost motion screw," being intended to
regulate or take up the lost motion be-
tween the striking finger and the shoe
on sticker.
The collapsing stroke of the pneumatic is limited by the striking of a pad or punching (P) against the end of screw (Q), said
screw being ACCESSIBLE FROM THE FRONT to permit adjusting by a long-bladed screwdriver. This is known as the "stroke
regulating screw."
The arms of the first and second tiers of pneumatics are connected by rods or wires (U) with the finger (V) pivotally connected
on the under side of lowermost Wind-Chest to rail (W). The lowermost tier of pneumatics has the finger attached direct to the pneu-
matic. This method of construction is especially adapted for pianos in which the piano actions are very short in vertical dimensions.
The pneumatics being mounted on an incline permit bringing the player action very close to the piano action, and also admit of
a very short, quick, powerful stroke. This system has the advantage of producing a wonderful legato touch, a delicate pianissimo, and an
astonishing forte. The means of regulation are also meritorious, being easily accessible from the front.
AMERICAN PLAYER ACTION CO
2595 THIRD AVENUE, NEW YORK