IMPROVEMENTS IN PIANOFORTES
Year: 1882

page_text: LETTERS PATENT to Friedrich Carl Glaser, of Berlin, in the Kingdom of
Prussia and Empire of Germany, Engineer and Patent Solicitor, for an
Invention of IMPROVEMENTS IN PIANOFORTES." A communication from
the Firm of Gebrüder Knake. Pianoforte Manufacturers, of Münster (West-
PROVISIONAL SPECIFICATION left by the said Friedrich Carl Glaser at the
Office of the Commissioners of Patents on the 7th January 1882.
FRIEDRICH CARL GLASER of Berlin in the Kingdom of Prussia and Empire of
Germany Engineer and Patent Solicitor. "IMPROVEMENTS IN PIANOFORTES."
A communication from the Firm of Gebrüder Knake, Pianoforte Manufacturers of
Münster (Westphalia) in the Empire of Germany.
This Invention relates to improvements in the repetition action of pianofortes, of
which the essential feature is an arrangement of certain novel parts whereby
soft and certain playing is produced; this latter object being also furthered by the
employment of simple parts and avoidance of unecessary friction.
This improved mechanism is represented in detail in the accompanying Sheet of
Drawing upon which: indicates the key of a pianoforte the hopper-i the
haminer the hammer butt-m the repeating lever-n a spring a lever turning
on ck the sliding lever the button-p the check.
I will now proceed to describe the operation of the several parts:-
On the key e being pressed down, the hopper f, by means of the hammer butt g,
raises the hammer up to the point h, that is to say, up to where it strikes against
the chords. The disengagement of the hammer from the hopper is effected in the
ordinary manner by the part of the bell crank lever f, k, striking the button 1,
which thus causes the disengagement. The hammer which would otherwise be
returned to its position at rest by its own weight is now held in suspended or
vibratory motion by the engagement of the hammer butt g at a with the repeating
lever m.
One arm of this lever m is rounded off in a manner corresponding to the
rounding off of the hammer butt, its other arm being provided with a screw thread
ID 11

page_text: and passing through a long oval holo in the hopper f; its extreme end being
securely connected to the lever turning on c. On the other side of the lever r is
a long spring n fastened to the said lever by means of a loop of silk or other
suitable attachment; the other end of this spring being firmly connected to the
part . By turning the nut which beds on a felt washer and piece of cloth, the
position of the repeating lever in relation to the part a may be adjusted. When
the mechanism is at rest (which is the position shown on the Drawing) m is not in
perfect contact with a; there is still a small interval of space between both parts.
By means of the nut the position of both parts may be so regulated that the
disengagement of the hopper f only coincides with the engagement of the repeating
lever m on part a of the hammer butt.
As, after the disengagement of the hopper as before mentioned, the hammer butt
nt a has arrived in contact with the repeating lever, the hammer is held in
suspended motion through the action of the spring being carried over to the
repeating lever.
This is the case on the key being pressed down quite gently. In ordinary
playing however the hammer springs back with force and is instantaneously stopped
If the hammer
by the check if the tips of the hammer have reached as far as o.
P,
performs the downward travel from / to o, the repeating lever m slides upon the
hammer butt at a, and in consequence thereof, the lever r, which moves on the
part, makes a movement in a forward direction, because the repeating lever is
screwed into the same. The spring n is thereby pulled, and the whole of the
tension power of the same acts on the hammer butt at a, by means of the lever m.
On the least setting free of the key by the player the repeating lever m is at
once ready to raise the butt, and consequently the hopper fiminediately catches
again under the butt at 8. The hammer can never fall quite down but is always
held in suspension by the spring. The spring t presses the hopper f against the
hammer butt.
Compared with the methods of construction heretofore in use, this construction
possesses considerable advantages. The great length of the spring n gives an
important elasticity to the repetition. As this spring is connected to by a loop
all friction is avoided. The force of the repetition does not in any way prejudicially
affect the hammer but is entirely transferred to the key and this causes an
extremely agreeable, quiet and sure playing both in the piano and in the forte;
further, increased durability of the mechanism is obtained, many pivots or working
points being avoided.

page_text: p. The check.
I will now proceed to describe the operation of the several parts.
On the key e being pressed down, the hopper f, by means of the hammer butt g,
raises the hammer up to the point h, that is to say, up to where it strikes against
the chords. The disengagement of the hammer from the hopper is effected in the
ordinary manner, by the part k, of the bell crank lever f, l, striking the button /
which thus causes the disengagement. The hammer which would otherwise be
returned to its position at rest by its own weight is now held in suspended or
vibratory motion by the engagement of the hammer butt g, at a, with the repeating
lever m.
One arm of this lever m, is rounded off in a manner corresponding to the
rounding off of the hammer butt, its other arm being provided with a screw thread
and passing through a long oval hole in the hopper f, its extreme end being
securely connected to the lever r turning on c; on the other side of the lever r is
a long spring n, fastened to the said lever by means of a loop of silk or other
suitable attachment, the other end of this spring being firmly connected to the
part k. By turning the nut v, which beds on a felt washer and piece of cloth, the
position of the repeating lever in relation to the part a may be adjusted. When
the mechanism is at rest (which is the position shewn on the Drawing) m is not
in perfect contact with a; there is still a small interval of space between both
parts. By means of the nut v the position of both parts may be so regulated that
the disengagement of the hopper f only coincides with the engagement of the
repeating lever m, on part a of the hammer butt.
As, after the disengagement of the hopper as before mentioned, the hammer butt
at a has arrived in contact with the repeating lever, the hammer is held in
suspended motion through the action of the spring being carried over to the
repeating lever. ♦
This is the case on the key being pressed down quite gently. In ordinary

page_text: playing however the hammer springs back with force and is instantaneously
stopped by the check p if the tips of the hammer have reached as far as o. If
the hammer performs the downward travel from hto o the repeating lever m slides
upon the hammer butt at a and in consequence thereof, the lever which moves
on the part, makes a movement in a forward direction because the repeating
lever is screwed into the same. The spring n is thereby pulled, and the whole
of the tension power of the same acts on the hammer butt at a by means of the
lever m.
On the least setting free of the key by the player the repeating lever m is at
once ready to raise the butt, and consequently the hopper f, immediately catches
again under the butt, at s. The hammer can never fall quite down but is always
held in suspension by the spring. The spring t, presses the hopper f, against the
hammer butt.
Compared with the methods of construction heretofore in use, this construction
possesses considerable advantages. The great length of the spring n gives an
important elasticity to the repetition. As this spring is connected to by a loop
all friction is avoided. The force of the repetition does not in any way prejudicially
affect the hammer, but is entirely transferred to the key and thus causes an
extremely agreable, quiet and sure playing both in the piano and in the forte,
further increased durability of the mechanism is obtained, many pivots or working
points being avoided.
Having now described and ascertained the nature of the Invention communicated
to me as aforesaid and in what manner the saine is or may be performed :-
:-
I claim as secured to me by the hereinbefore in part recited Letters Patent :-
The combination of the repetition lever m with the lever 7, by which the
spring n, after disengagement of the hammer i, so acts on the hammer butt g, by
means of the bent end of the repetition lever, that the hammer i can never fall
quite down, and upon the slightest liberation of the keys after the stroke of the
Hopper has been accomplished, immediately catches under the nut in order to be
ready for a fresh stroke.
In witness I the said Friedrich Carl Glaser have hereunto set my hand and
seal this Tenth day of June in the year of our Lord One thousand eight
hundred and eighty two.
F. C. GLASER. (LS.)