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THE MUSIC TRADE REVIEW
Being a Continuation of a Consideration of the Fundamental Principles
of The Player—The Pneumatic and Other Motors Discussed in an En-
lightening and Educational Way—What the Motor Must Accomplish.
The nature of the device used for the purpose
of controlling the selection of pneumatics to the
end that the player may sound the tones of a
• piece in due order, is such that it is most conven-
iently employed in the form of a long sheet, per-
forated from end to end, and then caused to
travel continuously over the series of ducts
massed on the tracker-bar. Music, be it remem-
bered, moves in time and not in space, and suc-
cession in time is essential to its performance.
Hence the necessity for presenting the sounds suc-
cessively, which in the case of the player mecha-
nism means that the music roll must travel. Hence,
again, we have the necessity for some machinery
for promoting the travel of the music sheet, and
this brings us to the motor, so-called, of the player
mechanism.
Now, before we can even understand the player
motor in its most elementary relations, we must
examine the nature of the functions which it is
to perform. These are two-fold. In the first
place, the motor must be capable of winding up
a sheet of music over the tracker-bar from end
to end steadily and reliably, without entailing un-
due physical effort or excessive consumption of
power. In the second place, it must combine with
this steadiness, a remarkable responsiveness to
control, to the end that instant changes may be
made from one rate of speed to another, readily,
simply and reliably.
Now, it is evident that the mechanical require-
ments of the motor are in the direction of light-
ness, ease of operation, small consumption of
power, and exceeding delicacy of response to con-
trol. The average music roll has a length of per-
haps 25 feet, while a roll of 50 feet long is quite
large, and one of 75 feet represents about the
maximum of length in general practice. Such a
roll as the last mentioned will be long enough to
reproduce a score lasting, to play, between ten
and fifteen minutes. A 50-foot roll weighs rough-
ly sixteen ounces unboxed. Thus it may be seen
that the maximum of work which is to be per-
formed by the player motor at the beginning of
a piece is no more than the overcoming of the
frictional resistance against the gradual unwind-
ing of the sheet, a resistance decreased in practice
by the fact that the gear ratios of the take-up and
roll-spools are very nearly the same at the begin-
ning of the work. As the winding proceeds of
course the resistance of the motor increases con-
stantly, since the weight of the paper, as it winds
up on the take-up spools, constantly increases.
Moreover, the gear ratio between the two spools
constantly operates against the motor, as the take-
up spool becomes larger and the other one smaller.
Thus the resistance against the motor increases
progressively from a minimum of almost nothing
to a maximum compounded of the total weight
of the roll multiplied by the adverse gear ratio.
But along with this slightness of power require-
ment goes a required delicacy of control that is
far more highly refined than is usual in small
mechanical motors. It is even more refined than
anything required usually in the electric motor.
Briefly, it is a requirement of instantaneous change,
instantaneous pick-up and instantaneous stoppage.
The motor must respond to every possibly con-
ceivable requirement of the performer in relation
to the most intricate and delicate phrasing. There
is no limit to the necessities of the case in this
direction. This introduces an element into the
problem which greatly complicates it.
Electric and Spring Motors.
'We are not here arguing for any one special
form of motor, for the particular case which we
are endeavoring to make will prove itself. If all
music rolls were phrase-recorded, so that no
changes of speed were required in the travel of
paper from end to end, the electric or the spring
motor would doubtless be perfectly satisfactory.
Indeed, we all know that players of the coin-
operated or film-player types are commonly fitted
with gears that drive the roll directly from the
motor which furnishes the power for operating
the exhaust bellows. Likewise, we know that
the Apollo player is fitted with a spring motor,
and the Apollo player is successful. But, in the
former case, the necessity for personal manipula-
tion is eliminated, while in the latter a hand-
played roll forms a usual part of Apollo equip-
ment, being made under the same auspices as the
player and being sold commonly with it. Indeed,
the general development of this player during the
last few years has been in the direction of pro-
viding complete automatic phrasing, dynamics and
bellows-power, from a central electric motor plant.
This development, of course, stands by itself, and
is quite apart from the ordinary player-piano in
which the bellows are foot-driven and a straight-
cut roll is so commonly used. Hence we are
obliged to regard it as in a class of its own and
as not coming within the purview of the present
remarks.
The pneumatic motor, driven by power pro-
duced from the foot-driven bellows, has become
the commonly accepted type of machine for roll
driving. The vast majority of player actions are
equipped with it and in most cases one sees noth-
'ng else. It is well that its principles and func-
tions should, therefore, be thoroughly understood,
especially in the light of what has been said
above.
Inflation and Deflation.
Suppose we take a pneumatic fastened trans-
versely to a wooden block, so that one wall of it
is movable, while the other is in contact with
the block. Then bore a hole direct through the
block and the fixed wall of the pneumatic, so that
there is a passage from the penumatic to the at-
mosphere. Then bore another hole half way
through the block, in line with and below the first.
When this has been done, bore another hole from
the end of the block at right angles to the direc-
tion of the first hole, till the two meet. Connect
up the remote end of the second hole with a tube
to an exhaust apparatus and ^you have a right-
angled channel from the exhaust tube up to the
surface of the block.
Now take a small wooden block that will slide
over the surface of the large one, so as just to
cover both of the holes in the surface thereof.
Hollow out this block on its under surface so
that when placed so as to cover the two holes,
the hollowed out portion makes a sort of cul-
vert or raised roof connecting the two holes. If
now you proceed to exhaust air from the tube
and right angled channel, the air in the pneumat-
ic will flow out through its atmosphere port, un-
der the hollowed roof of the block which covers
it and into the hole bored half way through the
block which forms part of the right angled chan-
nel. The pneumatic will then collapse. Move the
slide once more so that the port leading directly
into the pneumatic is uncovered, while the other
is still covered, and the air will flow into the
pneumatic again from the atmosphere, till the
pneumatic reopens. Keep on moving the slide
back and forth, and the pneumatic will alternately
collapse and reinflate, thus producing a reciprocat-
ing motion of its movable wall, which will per-
sist as long as the bellows below are in operation
and are displacing air from the exhaust tube.
Connect this moving wall by a connecting rod to
a crank shaft and your reciprocating motion be-
comes rotary, so that you can turn a wheel. That
is the pneumatic motor in rudimentary form.
Now, instead of one pneumatic, have three,
four, five or more arranged the same way on a
long block, each with one port running direct
through the block from the interior of the pneu-
matic to the atmosphere, and one bored half way
down to meet a right angled bore running through
the entire block and meeting each half-way bore
from each pneumatic. Have hollowed-out sliding
blocks movable on the surface of the main
bored block, one to each pair of holes correspond-
ing with each pneumatic. Connect each sliding
block to the crank shaft so that the slides will
move up and down as required by the principles
laid down in the previous paragraph for the one
pneumatic. Connect all the pneumatics to the
crank-shaft as above also, and you have a com-
plete pneumatic motor, less its governing valve.
The idea is simple enough, and its government
and control are equally simple. The whole opera-
tion of the motor depends of course upon the sim-
ple fact that when air is displaced by the action
of the exhaust bellows below, from any pneu-
matic where the position of the sliding valve
block is such that this can be done, the lowering
of interior air pressure in that pneumatic permits
the atmospheric pressure to be felt on outside of
the moving wall, which is pushed inward and
imparts a motion to the crank-shaft correspond-
ing thereto. When the slide is in the other posi-
tion the atmosphere flows again into the pneu-
matic, which opens. Thus the crank shaft makes
its complete revolution, or can do so, on the
operation of one pneumatic. If several pneumatics
are linked up in this way and are arranged so
that the motions of the slide-valves overlap ap-
propriately, and so that dead centers on the crank-
shaft are avoided, the motor will turn as long as
power is supplied—that is, as long as air is dis-
placed—through the action of the main bellows.
We must next take up the pneumatic analysis
of all this, as also the questions of power con-
sumption and pressure, and the still more im-
portant matter of analyzing the principles of con-
(To be continued.)
t
SPOOL FORjMJSIC ROLLS.
(Special to The Review.)
WASHINGTON, D. C, June 21.—A spool
for
music rolls in the invention of Charles T. Schoen,
Media, Pa., for which Patent No. 1,143,143 was
granted last week, the object being to provide a
music roll spool for use in player-pianos and other
musical instruments, which spool is also capable
of use in other instruments or apparatus where
an article rolled or wound on the spool is utilized
by unrolling or unwinding it therefrom.
Royal
Music
Rolls
There are all
kinds of music
rolls and ROYAL
ROLLS.
Royal rolls are cut in
conformity with the estab-
lished standard measure-
ments and we guarantee that
they will fit ALL standard
players.
You won't know roll satiafaetioa
until you play the Royal.
Royal Music Roll Co.,
BUFFALO,
N. Y.