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THE MUSIC TRADE REVIEW
11
Some Aspects of the Bellows Problem Considered with Some Suggestions of
Importance That Will Appeal to Those Engaged Either in Manufacturing or
Selling Player-Pianos—The Special Point at Which Designers Should Aim.
It will be generally admitted, we think, that the mospheric pressure. The cubical content of such construction throughout be absolutely air-tight,
various engineering problems connected with the a pneumatic as we have described above will be while also the pneumatic action and motor must
very likely about 5 cubic inches. Twelve of these, be designed so economically that waste space, if
design of bellows systems have not been discussed
then, will, roughly, have a volume of 60 cubic not entirely eliminated, will at least be reduced
at any time with any approach to agreement in
opinion. It will be generally admitted, in fact, inches, from which must be displaceable, instantly, to a minimum.
without undue effort, 11 per cent, of a normal
A good thought to leave with the reader at the
that the whole trend of player design in the past
few years has been toward the clearly distinguished atmosphere, or about 5.5 cubic inches of air. That close of this article is that bellows design must
being the case, it follows that the chest on which be considered as a part of, and not at all separate
types, radically different in the spirit of their
from, the general design of the player. One can-
construction and based upon radically differing the pneumatics are mounted must not be larger
than is absolutely necessary, but if we suppose that not think a bellows from one point of view, a
theories of function. It is not to be supposed, of
course, that all who have had to build bellows sys- this is rightly arranged we may also suppose that pneumatic from another and a motor from yet
tems have been clearly aware of the plain distinc- the cubical content of the chest will be at least another, with any expectation that the three can
tions involved. Many designers, in truth, would equal to that of any twenty pneumatics, with be put successfully together. The bellows system
their connections and valves. The latter may be is the power plant. The pneumatic action and the
be unable to express clearly their own beliefs and
opinions, or explain why they have adopted one taken as each approximately equal to one-half the motor are the consumers. Plainly, the latter must
be developed according to the requirements of the
ov the other system. But the fact remains that cubical content of each pneumatic.
former.
the two systems are clearly there and that every-
Calculations to Keep in Mind.
body belongs in one or the other camp.
Now, considering these facts, we see that we
Here, lastly, is one more thought. The design
have to devise a bellows system capable of pro- of the pneumatic action has yet to be thought out
In the present article we propose to consider
some technical aspects of bellows design, not so ducing as much as a 10 per cent, vacuum in a to the end. We have had too much mere experi-
mentation, too little real knowledge. Almost all
much with a view to making comparisons as for chest which will perhaps have a cubical content
the purpose of stating facts. The truth of the of 100 cubic inches. While, therefore, to obtain the pneumatic actions now on the market could
matter is that precise information is not so easily a maximum of force on one chord only it would be made smaller, could be designed more eco-
be necessary to displace no more than 6 cubic nomically and could be less power-wasting. When
had as is indefinite opinion. Anyone can say what
inches of air instantaneously, on the other hand, to pneumatic actions are built more economically,
he likes. But few can give any particularly good
reason for liking or disliking anything. Here we maintain a maximum of force it will be necessary then bellows systems also will benefit.
shall supply some data that may help to provide to maintain a continuous displacement of 10 cubic
inches of air; that is, to keep air moving out to AUTOMATICALLY OPERATED PIANO.
reasons, as aforesaid.
the atmosphere at the rate of 10 cubic inches per
The Function of the Bellows System.
Details of the Latest Invention of Axel G. Gul-
The function of the bellows system is two- unit of time.
bransen—Devoted to Improved Means for
Now, it is obvious that in designing a bellows
fold. Basically, it is a power plant and nothing
Supporting Automatic Action Mechanism.
system we must keep in mind such calculations as
else. But incidentally it is also a controller of
(Special to The Keview.)
these. Very likely, of course, it would not occur
power. In other words, through one and the same
that the exact figures here given would apply, for
WASHINGTON, D. C, November 19.—The Gul-
mechanism we produce power and control it. This
in each case pneumatics and general construction bransen-Dickinson Co., Chicago, 111., is the owner
is one point to be kept in mind.
will differ. But they cannot differ largely from through assignment by Axel G. Gulbransen, same
Now, there is another point of equal impor-
tance. The design of the bellows system must be the dimensions suggested. Certainly they cannot place, of patent No. 1,078,673, for. an automatically
such that the highest vacuum level may- be had be much larger. Valves, passages and waste space operated piano, and is directed toward improved
easily, while at the same time the lowest possible of that sort, especially in a double-valve player, means for supporting the automatic action mecha-
will affect the total dimensional figures, and the nism within the casing of an ordinary piano so
level is available instantly, together with all grada-
designer should know exactly what he is doing that it may be properly associated with the keys
tions in between. The propelling power being
in
regard to these.
for the purpose of operating them precisely as if
the human foot, it follows that the size and inertia
The first thought that will occur to the reflective they were operated manually in the usual manner.
of the bellows units must be within definite limits.
mind is that a bellows system which is to dis- It is well known that in automatic piano actions
The first requisite of a successful bellows system
is ease of operation. Stiffness and sluggishness charge the amount of air indicated above must be which are operated pneumatically a "channel
large and powerful. But it is also to be remem- board" is provided which extends the length of
are unpardonable.
Allowing for this limitation, the next considera- bered that it is out of the question to build a the piano at the front thereof and has a multi-
tion is as to the amount of power required. This system larger than can easily be operated by the tude of "pneumatics" secured to the rear thereof
feet. In point of fact, a bellows unit should not and directly associated with the abstracts of the
may t»e expressed by saying that the maximum of
power needed is that which will enable the in- have a moving wall with an area of more than piano action proper. These channel boards are
fliction of the hardest possible blow upon one or 120 square inches. Given units of this size, with made of wood and are provided with vacuum
more piano hammers. That is another way of light spring expansion (say 14 pounds) and an chambers and air passages of different kinds, de-
absolutely air-tight construction, there will be no pending upon the precise nature of the pneumatic
saying that, in practical playing, the maximum of
power is that which is required to actuate, simul- difficulty in getting the desired displacement, nor system employed.
It is the specific object of this invention to pro-
taneously, perhaps as many as ten or twelve ham- will the physical effort involved be too great.
What Designers Should Aim For.
vide means for properly mounting this channel
mers with enough power to obtain a fortissimo
'Brushing aside for the moment these engineer- board.
result. Now, if we suppose that the area of the
As is probably well known in the art of
moveable wall of a pneumatic is 5 square inches, ing considerations, one may press home the
thought that the whole aim of designers should player manufacture, these channel boards are not
and that twelve of these are actuated at once, it
follows that the total area to be acted on is 60 be to build bellows systems that can be manipu- very wide relative to their length and they are
square inches. In order that the external air pres- lated by a woman or child. This ideal has not subject to warping, often to such an extent as to
sure may act upon this area in such a way been as well conserved as would be desirable, but make their proper disposition in the piano casing
as to produce the hardest sort of blow, it will be its truth is gradually coming to be perceived. But a serious difficulty. This invention is effective in
it must also be remarked that in order to satisfy providing an arrangement whereby this warping
necessary to have an external pressure of about
such a requirement, together with the other desid- may be met and overcome, and whereby the chan-
24 ounces to the square inch. Twenty-four ounces
approximately equal 11 per cent, of normal at- eratum already discussed, it is necessary that the nel board may be properly adjusted in position.
PIANO
NATIONAL
IMickel-in-ttie-Slot
Tlie "No Trouble" Playcp
NEW ART STYLES
MANDOLIN, a n d t h e N e w VIOLIN-FLUTE
ATTACHMENT
NATIONAL PIANO PLAYER CO.
OREGON-ILLINOIS
ipr Descriptive Cateloane
Continuous Roll, and Automatic
Rewind Styles—Also 88 Note Pedal
and Combination Pedal apd flee*
trie Styles,