Year: 1888

page_text: I GEORGE FINCHAM of Bridge road Richmond in the Colony of Victoria Organ
builder do hereby declare the nature of this invention and in what manner the samo
is to be performed to be particularly described and ascertained in and by the following
statement:-
This invention of an automatic exhaust valve has been devised for the purpose of
allowing a rapid escape of the residue of pressure from air chambers of organs when
the air pressure to such chambers has been cut off and it is of especial value in organs
in which the tubular pneumatic takes the place of mechanical actions inasmuch as it
ensures a rapid repetition of the note sounded-It consists of an exhaust valve so
constructed as to be normally open and to close when and for so long as an air
pressure is supplied to the chamber or tube to which it is attached, such air pressure
acting as the operating medium for closing it and keeping it closed-Whenever this
air pressure is cut off my valve automatically opens and thus allows a rapid escape of
the contained air pressure.
In actual practice I make my valve in the form of an unevenly balanced lever
arranged outside the air tube or chamber on which it is to act and having one end
longer and heavier than the other-I furnish the longer end with a leather pad to
cover the exhaust opening while behind the tail of the shorter and lighter end of the
lever I make another and larger opening through the wall of the chamber or tube and
cover its outer face with a diaphragm of soft leather or other material sufficiently
pliant as to be capable of being pursed or extended outwards to such an extent as to
push the other end of the lever and close the exhaust-This lever valve I secure in
position preferably by a leather connection piece forming a hinge-It may either be
arranged in a vertical or a horizontal plane or at any plane between them as it 'acts
automatically in either position by reason of the preponderance of weight in its
opening end where the exhaust operates so that when the air pressure in the tubes or
chamber is sufficiently reduced the exhaust moves to its open position.
The attached drawings illustrate my invention.
Figure 1 shews a section through a part of a pneumatic chamber fitted with my
exhaust valve.

page_text: Figure 3 a section of a pneumatic chamber having my exhaust valve arranged on it
in a different position to that shewn in Figure 1.
A is the pressure chamber and B the air inlet pipe or tube leading thereto-C is
the exhaust opening-D the lever or flap-valve having a leather cushion or pad D¹
secured on it to fit over the exhaust opening C-This valve D is supported by a
leather hinge D2 in the position shewn while its tail or lighter end is formed of a
tapering thickness and behind such tail end an opening E is made through the wall
of the pressure chamber A-The outer face of this opening is covered with a flexible
diaphragm E which is pliant enough to allow of its working the lever to close the
exhaust opening.
The mode of operation is as follows:-When the pressure chambers are furnished
with my automatic exhaust valves and the air pressure is led to one of such chambers
such air pressure is exerted on the diaphragm thereby pressing out the tail of the
valve-lever sufficiently far to cause its other end to close the exhaust opening. When
the pressure is cut off from the chamber the preponderance of weight at the exhaust
end of the lever tends to make it fall or gravitate to its open position this tendency
being aided by the residue of the pressure within the chamber.
Having now particularly described and ascertained the nature of my said Invention
and in what manner the same is to be performed, I declare that what I claim is :-
My automatic exhaust valve for use in organs consisting essentially of an unevenly
balanced hinged lever having a suitable pad or cushion at its one end to cover the
exhaust opening its other and shorter end being arranged over a flexible diaphragm
covering an opening in or leading to the pneumatic tube or chamber substantially as
herein described and explained and as illustrated in my drawings.
Dated this Twenty-second day of November one thousand eight hundred and
eighty sovan