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THE MUSIC TRADE REVIEW
11
The Design Problems Connected With the Motor of the Piano Playing Mechan-
ism the Subject of an Important Analysis—The Pneumatic Motor, The Subject
Under Discussion—Considerable Information Given That Will Be Helpful.
Tlic object of the present article is to consider is pierced with a channel. From this channel runs involved in moving the take-up spool, when loaded
briefly the design problems connected with the a passage into each bellows through the fixed wall with the weight of 100 feet of paper, at a speed
motor of the piano playing mechanism. We shall Below this passage on the fixed wall of each bel- of 13 feet to the minute. In other words, the ef-
speak of the pneumatic motor especially, for the lows is a second part or passage, piercing the trunk fort involved in turning a roll of the greatest
reason 'that this type is more generally used than board below the channel, which it does not enter, length in use at the maximum speed, and in doing
any other. Again, the pneumatic motor to which and thus providing a direct passageway from the this as well at the end as at the beginning of the
we shall refer is a special type of air engine, since outer air to the interior of the bellows. Thus piece constitutes the maximum of the motor's
air is exhausted from it rather than pumped each bellows is provided with two ports leading work.
forcibly into it. Our inquiry, then, narrows itself out from it, one leading to the channel and the One need not consider the rewinding process
down to a discussion of sub-normal pressure air other to the outer air. These two ports are placed with such particularity, since this is only gone
engines specially built for the purposes of the in line one below the other. A slide valve actuated through when the full power of the main bellows
piano playing mechanism.
by the crank shaft controls these. When the slide is available for that one purpose.
Some Further Considerations.
In order that the principles which are to govern covers both of the ports communication is opened
A further consideration is bound up with any-
and control the evolution of a machine may be between the interior of the bellows and the channel.
utilized rightly it is evident that they must be When the slide is in the other position the bellows observation of the valve system. The first motors
capable of definite expression. And in order that is in communication with the open air and shut off were built with wooden slide valves, sliding on
this expression may be possible, it is also necessary from the channel. The channel is the medium wooden seats, but these were gradually superseded
that the precise object of the mechanism should whereby the main bellows system is enabled to by constructions in which metal seats were sub-
exert its suction power upon the units of the stituted. Still later there has been a return to the
be accurately stated. This we must first do.
motor, and thus the slide valve alternately pro- wooden construction, but the expedient has been
The Object of the Player Motor.
The object of the player motor, then, is to turn vides for the collapse and re-inflation of the bel- quite generally adopted of using hard wood for
the take-up spool of the player at a speed varying lows. This produces a reciprocating motion, which the sliding surfaces. In spite of this, however,
from zero to about 13 feet per minute, and to have is transformed into a rotary motion by means of a valves are inclined to be troublesome at all times,
crank shaft and connecting rods.
largely owing to the almost inevitable warping of
enough power to overcome not only the inertia of
the surfaces. What is above all needed for this
The Bellows Units.
the spool, but that of the music roll which winds
up on the latter. This is the primary requirement.
The number of bellows units varies from three construction to be fool-proof is a form of slide
A secondary but equally important requirement to six. Each is, of course, single acting, although that shall not warp, but shall at the same time be
is that the motor must be exceedingly responsive double units may be used if required. The valves light enough; together with means for connecting
up the slide with the crank shaft so as to eliminate
to speed control, so that under any given load con- are related to each other, as to the periods of
dition the performer may alter the speed instanta- their motion, in such a way as to assure that there friction and the necessity for artificial lubrication
"shall be as near as possible continual torque or of the parts.
neously within the prescribed extreme limits.
A motor built by the A. B. Chase Co. is interest-
A third requirement is that the motor should be turning power.
Now, it is obvious that this design is simple ing in this respect because of the use of glass slides,
able to re-wind the roll off the take-up spool at
enough, but it is equally obvious that it is sus- and the substitution of direct contact cams for
high speed.
A fourth requirement is that the demands upon ceptible of refinement. For one thing, the ob- cross heads on the crank shaft. The Cable Com-
pany has also taken steps in the direction of elimi-
the bellows system of the piano player should not server will at once detect the very plain fact that
be high enough to compel any undue physical ef- the form of bellows generally employed is not ex- nating troubles by the use of fiber and babbitt
fort in order to provide the power' to run the motor actly efficient in the sense that its power is not metals at the bearings, thus avoiding necessity for
under all conditions comprehended within the evenly distributed throughout its back-and-forth artificial lubrication.
The motor of the player, if it is to be thoroughly
stroke. The pull upon the crank shaft continually
above review.
efficient, must be light, not too powerful, but just
A fifth requirement is that the motor should be depreases in effectiveness from the beginning of
small, so that it occupies very little space; simple, the stroke until the end. This is due to the powerful enough, fool-proof and capable of run-
so that it requires little attention, and reliable, so triangular form of the bellows whereby the motion ning for months at a time without attention. The
is rather through an arc of a circle than in a requirements are not at all slight, and it is evident
that it does not get out of order at all readily.
To summarize, then, the pneumatic motor of the straight line. Here is an element of power waste that, along the lines mentioned above, there is
much opportunity for further refinement.
piano player is to be a vacuum engine designed to not always considered.
It would thus seem that there is a chance for
occupy a very small space, to be exceedingly light
and simple, to be exceedingly rapid in response to improvement of the form of the bellows units.
PLAYER MEN VISIT MILWAUKEE.
control, to be capable of a wide range of speeds Something might be done in the way of making
Alfred D. Engelhardt and Fred Ackerman, of
under all conditions in which it may have to work, the bellows units of the motor in the form of
New Engelhardt-Seybold Combination, Call
to make very small demands upon the bellows sys- diaphragm pneumatics. The Henry F. Miller
on Trade in That Progressive City.
tem for power and to carry light loads under con- player-piano is thus fitted. Then again we have
tinually varying conditions instead of heavier loads the possibility of substituting cylinder and piston
(Special to The Review.)
for the leaf or diaphragm pneumatic. The Gul-
under conditions more constant.
MILWAUKEE, WIS., January 27.—Emil O. Schmidt,
bransen-Dickinson Co. manufactures such a motor,
The Vacuum Engine.
representing the Chickering & Sons, Kranich &
The vacuum engine, as we all know, operates on which is successful.
the principle of sub-normal pressure. That is to In connection with this point it might be well to Bach, Seybold and Berry-Wood lines, had as his
say, the pressure of air contained within it is re- point out that, generally speaking, player motors guests last week two well-known men—Alfred D.
duced by the action of exhaust bellows so that the have an excess of power. The point involved was Engelhardt, of F. Engelhardt & Sons, and Fred
Ackermann, of the Seybold Piano & Organ Co,
external air exerts a positive pressure against the well illustrated in a remark made by an eminent
outer walls, or against the side of a wall or piston, designing engineer, to the effect that the player and the members of the new Engelhardt-Seyb)l 1
while the internal reduced pressure air is on the built by him had a motor capable of running a Co. Both Mr. Engelhardt and Mr. Seybold seemed
other side thereof. The usual construction adopted sewing machine. Doubtless this was true; but who to be favorably impressed with the Milwaukee
field for automatic pianos and orchestrions.
t > cnrry out this idea is embodied in a series of wants a player motor to do anything of the sort?
While in Milwaukee Mr. Engelhardt said that the
small bellows, each of which is provided with one The business of the player motor is solely to turn
new Engelhardt-Seybold Co. will have its main of-
fixed wall and one movable wall. The fixed walls music rolls, and the maximum effort it is called
of the series are joined on one trunk board which upon to exert during the process of playing is that fices in Chicago and that he will be in charge.
PIANO
NATIONAL
IMickel-In-ttie-Slot
Thie "No Trouble" Player
NEW ART STYLES
MANDOLIN, a n d t b e N e w VIOLIN-FLUTE
ATTACHMENT
NATIONAL PIANO PLAYER CO.
OREGON-ILLINOIS
Write for Descriptive Catalogue
Continuous Roll, and Automatic
Rewind Styles—Also 88 Note Pedal
and Combination Pedal and Elec-
tric Styles.