Music Trade Review -- © mbsi.org, arcade-museum.com -- digitized with support from namm.org
MARCH 30, 1918
THE
MUSIC
TRADE
9
REVIEW
The Advantages Presented By a Player Mechanism Embodying Piston Pneu-
matics Are Sufficient to Make Worth While a Serious Discussion of the Pos-
sibility of Removing the Technical Difficulties of Constructing the Same
Only the other day the writer of this article
was talking with an engineer, one thoroughly
acquainted with vacuum machinery of all sorts
saving and excepting the mechanism of player-
pianos. The conversation turned upon the
player-piano, as it happened, and the engineer
wished to know whether any attempt had been
made to embody the piston in place of the leaf
pneumatic in player actions, and if so, what had
been the measure of success. He was of the
opinion that the player action must finally be
metallic in construction and that the leaf pneu-
matic cannot forever hold its own against
forms of pneumatic machinery long since proved
far more efficient in other types of machine.
Metal Construction
Now it happens that a metal player action,
embodying piston pneumatics, was built and to
some extent used in England some six years
ago. Paul B. Klugh, who at the time was as-
sociated with the Cable Company, of Chicago,
obtained one of these actions in an English
piano, and it was seen by a number of tech-
nical men, including the writer. This action
had many interesting and original features. The
general and underlying idea was, of course, the
piston pneumatic, which is worth describing, for
the double purpose of considering its potential
advantages and its probable weaknesses.
Cylinder Pneumatics
The idea of the inventors was to provide an
action working on high tension, in which the
operating units (pneumatics) could be so small
as to be placeable in a single row, each in front
of its corresponding unit of the piano action.
It was therefore necessary to build each unit
on a very narrow scale, of course, and the pis-
ton idea was adopted. The units were made
as metal cylinders, just wide enough to fit in
between the abstracts, the movement of which
was secured by pistons of hard graphite, sliding
in the cylinders.
The diameter of each cylinder was one-half
inch and the piston of corresponding size. Now
it will at once be seen that in order to obtain
the necessary power through a unit of such
small efficient area as a half-inch piston, the
pressure at which the same is caused to move
must be very much increased. In fact, the area
is not more than one-tenth that of the ordinary
leaf pneumatic, and in consequence the effective
playing pressure must be very much greater
than what we are accustomed to. Naturally, a
metal action was adopted, for the most obvious
mechanical reasons. In the action to which ref-
erence is now being made, however, it was found
t! at the actual pressure per square inch upon
the operating parts is never anything like as
high n proportion as would be expected from
the decrease in area. In fact, the velocity of the
air movement makes up very largely for all in-
creases of power made necessary by the reduced
size of the parts.
The cylinders are open towards the bottom
and the pistons work upwards inside them.
The primary and secondary valves are arranged
immediately above the pistons in two chests,
one behind the other, and the primary chest con-
nects with the bellows through a separate suc-
tion tube which passes through a governing valve
whereby the tension is reduced; so that the pri-
mary action works on low tension, low enough
to make sure that the paper will not stick while
traveling over the tracker bar. Each primary
valve consists of a loose plunger lifting a con-
ical valve while the secondaries are also
plungers lifting loosely-seated metal balls.
So much for the top action. The bellows
system is, of course, designed to give high
tension and has features of marked originality,
the units being constructed in the piston and
cylinder type also. But this need not now de-
tain us. Let us preferably consider the possi-
bilities and probable defects of the cylinder
pneumatic considered generally and broadly.
Size
In the first place, as a primary advantage we
may consider the question of size. It is ob-
vious that a player action in which the pneu-
matics may be placed in one rank immediately
in front of the abstracts of the piano action, is
also one which may be built in less than half
the space now occupied by the ordinary valve
and pneumatic stack of the ordinary player. It
is also -fairly obvious that if a cylinder-type
metal action could be built like this, it could
also be built with the cylinders and valves in
sections of six to ten or more apiece, and there-
fore could be made in stock styles to fit any
scale.
The question of tension is also important and
interesting from the practical standpoint. There
is nothing to prevent the use of high tension
pumping units for foot-power, when the top ac-
tion units are so small, for the amount of waste-
air space is naturally very small, too, and much
more easily handled than the similar volumes
of waste-air in an ordinary player.
Moreover, for reasons which have already been
fully discussed in this department, there are posi-
tive advantages in operation under high ten-
sion. The main advantage, of course, lies in
the higher velocity of the air and the conse-
quent greater rapidity of action of the valves,
etc.
Touch
But the direct action of the cylinder and pis-
ton constitutes, of course, the main value of
the system. The leaf pneumatic works indi-
rectly upon the piano through a series of levers
which are more or less complicated and which
involve several friction points. Expense, waste
oi space and complication are the natural con-
sequences of this. All the advantages, so far,
are on the side of the cylinder, which, moreover,
without doubt will work better on pianissimo at
high speed through the absence of undue fric-
tion between the pneumatics and the piano ac-
tion. There are many other advantages depend-
ent on this, the nature of which will occur to
the technical reader.
Disadvantages
We may now consider the other side of the
pcture. The metal action has not been so un-
measured a success that one is likely to hear
its claims go unchallenged. On the contrary,
we may be sure that there will be searching
criticism. Indeed, there is little doubt that the
small success, on a commercial scale, of the
Brit sh action to which we have referred, was
as much due to the difficulties of its metal con-
struction as to the outbreak of war in 1914.
The pecv.l'arities of metal construction are
many, and it would seem as if recent develop-
ments in the art of die-casting point to perhaps
the only possible way of getting around the
very difficult problem of air-tightness combined
with accessibility. It is easy enough to make
a seamless metal box as air-tight as you please;
but to make it internally accessible and at the
same time air-tight, is quite another matter.
Lubrication
A second difficulty is connected with the lubri-
cation of the pistons in the cylinders. In the
action to which we have referred at length the
lubrication is provided by the manufacture of
the piston from a composition of graphite and
carbon. It was claimed by the inventor that
this material is quite self-lubricating, and the
claim no doubt may be admitted. But it was
also claimed that it was indestructible, or at
least did not wear out for an indefinite length
of time; which claim is considerably more
doubtful in every way. Still it is hard to see
how a piston type of action could be built ex-
cept the pistons are either self-lubricating or
lubricable with dry lubricant of some form such
as powdered graphite. The difficulty, of course,
is complicated by the fact that the owner of a
player-piano resolutely declines to touch the in-
side of his instrument to lubricate or to do any-
thing else with it. lie will spend hours lying
on his back looking up at the differential or
the transmission of an automobile, but not a
second dropping a little lubricant upon the chain
or gear wheels or brake of a pneumatic motor,
Therefore, it becomes almost a matter of prin-
ciple that the top action should not need any
artificial lubrication but should be foolproof al-
together in this respect. The cylinder and pis-
ton has not in this respect the advantages of
the leaf pneumatic, for the friction of piston
with cylinder must be overcome, and apparently
the only way in which it can be overcome is
by the use of a graphite composition.
Cost
The question of cost then comes into the field.
There is no doubt whatever that, up till now,
metal actions, along with any other difficulties
that may be theirs, have been found to be more
expensive to build. In these days a player man-
ufacturer, no matter how desirous he may be
of improving his product, must consider costs
with utmost care. The cost question is one
therefore that must be settled favorably before
any experiments along the lines indicated will
be worth consideration from a practical stand-
point.
Summary
Nevertheless, the action mentioned above, and
the ideas which gave rise to it, are alike inter-
esting and informative. In respect of touch
and response the small-size high-tension pneu-
matic is unsurpassed and far superior to any
rival. That much is sure. The advantage is
big enough to be worth the most careful cdn-
s deration, for if the difficulties which have been
pointed out could be overcome, as they can un-
dorbtedly be, many new and great advantages
would be gained and a new epoch in develop-
ment would be marked. The foregoing remarks
are intended as a contribution to this end.
Hiram Schumacher and li's brother Oliver,
piano dealers of Toiedo, ()., lave made arrange-
ments to close out the r piano bus nei.-;, pre-
paratory to entering military service.
Simplest and Best
The GEORGE P. BRAND
Mechanical Tracking Device
Destined to be the Standard
in the trade
Manufactured by the
BRAND PLAYER ACCESSORIES COMPANY
140th Street and Jackson Avenue, New York