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THE MUSIC TRADE REVIEW
Some Interesting Facts and Figures Regarding Power Usage and Wastage
in Player-Pianos-The Results of Exhaustive and Accurate Tests Presented
in Chart Form—The Many Varied Factors in the Consumption of Power.
pneumatics is extremely small in proportion.
We need not point out, of course, that to have
anything like accurate data in matters of this sort
is of the highest importance, because only thereby
can one be enabled to quit the valley of indecision
and the fog of guesswork for the higher levels of
science. The more we know of such matters as
these the more guides we have in trying to find
the way to the perfect design. Hence the im-
portance of accurate experiment and sound pre-
liminary scientific training.
The assertions which have been made in this
department regarding the distribution of the power
From time to time in the Pneumatic Depart-
ment of the Player Section we have directed at-
tention to important questions relating to con-
sumption of power in the player mechanism. We
have pointed out that exact knowledge on this
topic is scarce and that there is much confusion
in the minds of technical men, not to mention
dealers and salesmen, in connection with the en-
tire matter. In some recent articles we have in-
sisted on the assertion that the proportion of the
total power input (whether this arises from the
direct operation of foot-driven bellows units or
from some form of power-driven vacuum ap-
ALOCIAN CO 1 *. ROLL aoi3o.
WATTAGE: CURVES OF
— Music ROLLS.-
Longitudinal spaed one » one half" inches per
Cach verlical spacs 125 waifs.
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inu Co'3. graphic waKnwtcr-,
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Kccerd made Jan. 17- 1916
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paratus) absorbed in the operation of the roll
driving motor is unreasonably large, amounting
to not less than 50 per cent, in many, if not in
most, cases. We have also pointed out the high
probability that experimental analysis would show
the greater part of the remaining power input to
be absorbed in the operations incident to main-
taining a partial vacuum in the chests and that
the actual condensation in these chests produced
by the direct flow of air into them from collapsing
1
1
\.——
I
input were based upon purely mathematical rea-
soning and lacked experimental verification.
Owing, however, to the kindly interest of a friend
whose eminence in the world of engineering is
generally acknowledged by his contemporaries, but
who prefers not to have his name mentioned, as
he has no other than a scientific interest in the
matters at issue, we have been enabled to obtain
some extremely interesting graphic records re-
lating to the general subject of power consump-
tion and its important subdivisions, distribution of
input, proportion of total power absorbed by
motor, etc. Thus the technical readers of The
Review may obtain some definite facts upon which
to base further experimentation with a view to
further improvement.
A few words of explanation are necessary con-
cerning the chart records herewith shown.
These curves are graphic records taken on a
recording wattmeter and show the fluctuations
in wattage for an electric motor used in driving
the vacuum system of a player-piano. The rec-
ords were made, as will be understood, while the
player-piano was being used in the performance
of the various pieces whose names are appended.
They do not show directly the rise and fall of
vacuum level, but rather the rise and fall of
electric power consumed in generating the various
vacuum levels required and attained during the
performances of the pieces mentioned. Hence
the indications are indirect, although at the same
time accurate, for it is plain that the electric
power consumption varies directly as the load on
the vacuum system. While, therefore, a given
peak in a curve might merely mean that many
pneumatics are speaking on a low level of tension,
this is in effect the same thing to us as the speak-
ing of fewer pneumatics on a higher level, since
for our purposes the important fact is as to the
displacement capacity of our player primarily. It
must be understood that the player-piano from
which these records were made is operated by a
somewhat unusual and entirely original type of
vacuum system whereby a constant level of forty-
four inches water column is maintained, the lower
speaking level being reached through expression
governors. The wattage curves are therefore di-
rectly indicative of the fluctuations in displace-
ment quantities; that is to say, in the amount of
air being displaced from moment to moment.
Operating with a Blower.
The player-piano is power driven by a \ x k-
horse-power electric motor operating a six-stage
centrifugal vacuum blower in place of the ordi-
nary exhaust bellows. A vacuum of forty-four
inches water column is maintained at the player
constantly. The fact that the exhauster works
constantly and not reciprocally has the effect, of
course, of flattening somewhat the curves, since
there is a certain amount of stored energy in the
motor, as it were, due to the flywheel effect of
steadily rotating parts. With a reciprocating bel-
lcws system, such as is generally used, the curves
would have sharper slopes and peaks.
To anticipate objections from the start let it be
said that the player operates on 7 inches water
column when governed down to the minimum and
that changes from this level up to forty-four
inches can be had instantaneously. Forty-four
inches water column correspond to about \Vz
pounds effective pressure per square inch. It is
admitted that this high vacuum maintenance is
expensive relatively speaking, as the motor uses
1,125 watts, but the dynamic effects possible with
such a power reserve justify any expense in-
volved. Moreover, the curves are not in the least
invalidated as authorities in our discussion, for
they are substantially accurate in proportion to
any power level postulated. A system of opera-
tion based on a normal maximum and throttling
down to the speaking power required from
moment to moment, has, of course, the immense
advantage that all non-speaking pneumatics oper-
ate instantly, without any chance of their refusing
to work through lack of power. Also it means
(Continued on page 8.)