A Repetition Mechanism for Pianos.
Year: 1891

page_text: Date of Application, 28th Mar., 1891-Accepted, 6th June, 1891
COMPLETE SPECIFICATION.
A Repetition Mechanism for Pianos.
I, VALENTIN BERDUX of Friedensstrasse Heilbronn, in the Kingdom of
Württemberg, Empire of Germany, Manufacturer, do hereby declare the nature
of this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
The object of this invention is an improvement in the mechanism of pianos having
for its purpose to attain, when repeating music passages an always completely
uniform power also with very gentle touching of the keys. The essential features
of the improvement are as follows: The pushing surface of the hopper is arranged
as close as possible to the fulcrum of the hammer so that a slight movement of the
hopper causes the hammer to strike. Said surface lies at its highest or at its lowest
position equally high above or below the fulcrum of the hammer. The pushing
surface of each hopper is furthermore capable of being for itself so regulated in
its position to the hammer butt leather as to constantly be in contact with the latter
while the hopper is removed from the hammer butt only so much as is absolutely
required for catching the haminer, so that the least release of pressure on the key
brings the pushing surface again direct below the hammer butt surface and causes
the hammer to strike by slight key pressure.
In the arrangements hitherto employed, the hoppers lean in the resting position
of the hammer against a felt cushion, which cannot be regulated, and partial
swelling of the cushion through climatic influences frequently causes the pushing
surfaces of the hoppers to catch unequally and irregularly under the hanımer butts,
thereby diminishing the power of the striking effected by the mechanism.
Another drawback of the mechanism beretofore employed consists in the difficulty
of regulating the backward movement of each single hopper with the release of the
hammer, all hoppers leaning after the catching of the hammer against one through-
going bar covered with felt.
Referring to the accompanying drawing
Fig. 1 is a front view,
Fig. 2 a side view, and
Fig. 3 a detail view of the improved arrangement intended to remove the
inconveniences mentioned above.
The hopper B formed as an angle lever and lodged as in most mechanisms in an
arm of lever A, has two shanks 6 and . The vertical shank 2 is provided with
an adjustable projection a serving to regulate the pushing surface in its distance
from the hammer fulcrum o³. The releasing itself is effected by the known arrange-
ment of the striking of the projection of the horizontal hopper shank against the
adjustable abutment a² of the bar G. An abutment a' adjustably lodged in lever A
and against which abuts the horizontal hopper shank 6 serves for regulating the
backward movement of the vertical shank .
On the lever A being pressed upward about pivot o' by means of the key, omitted
in the drawing, the damper E is pressed away from the string S by projection / and
damper rod e; the hammer C is seized by shauk under the leather c³ of butt c' and
turned about fulcrum o³ until the hammer strikes. At the last moment previously
the hopper shank 2 moves back, that is to say the releasing commences, and the
check D and the counter check come into action. The rearward movement of
the vertical hopper shank is terminated as soon as shank leans against
abutment a'. The latter being adjustable the deviation can be so regulated that,
also with the greatest deviation as indicated by dash- and dot-lines in Fig. 3, the
pushing surface of the hopper so catches under the hammer butt leather c³, that,
on the slightest release of pressure on the key, the hopper shank 6' moves rapidly

page_text: again under the hammer butt c¹ and a slight key pressure again actuates the hammer
that is to say renders the repetition complete.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, 1 declare that what I
claim is :
A repetition mechanism for pianos characterised by an arrangement for so
regulating the vertical shank (2) of each single hopper (B) and therefore also its
pushing surface by an adjustable abutment (3) as to cause the pushing surface to
always catch direct under the leather (3) of the hammer butt in such a manner
that the hammer can be made to strike in any position of the key by means of
slight key pressure, while the movement of the pushing surface of each single
hopper can likewise be so regulated by an adjustable abutment (a) lodged in lever A
and acting against the horizontal hopper shank () as to effect the release in such
a manner, that the slightest release of pressure on the key brings the hopper
shank with its pushing surface again direct under the hammer butt leather (³),
thereby rendering a striking of the key at once effective, the whole substantially as
illustrated and described.
Dated this 28th day of March 1801
VALENTIN BERDUX.
By Huelser & Co.,
Temple Chambers, London, his Agents.