US1197596A - Pneumatic action for pianos. - Google Patents

Description

W. G. BETZ.

PNEUMATIC ACTION FOR,P|ANOS. APPLICATION FILED MAY8.19I4.`

l 1 97,5 9 6 I. Patented Sept. 12, 1916.

WILLIAM G. BETZ, OF BUFFALO, NEW YORK.

PNEUMATIC ACTION EGR PIANS.

Specification of Letters Patent.

Patented Sept. 12, 1916.

Application led May 8, 1914. Serial No. 837,130.

specification.

My invention relates to pneumatic actions for pianos, the principal features looking` more particularly to a simplified valve construction and the method of supporting the action levers controlled thereby. Referring more particularly to the valve mechanism, I have found that with my construction a very effective control of the hammer action is secured and one in which a smaller air duct or vent in the tracker bar may be used and Still secure a very .good operation. Also I have so hung the action levers that said levers and their supporting arms may be independently removed. A

I will now refer to the accompanymg drawing for a better understanding of my invention in which like reference characters indicate like parts and in which- .Figure 1 is a sectional view illustrating the control mechanism of one key; Fig. 2 is a face view of one valve mechanism with the cover of the air chamber removed; Fig.

3 is a side elevation of a valve lever; Fig.

lis a left side view of Fig. 3; Fig. 5 is a detail view of a combined valve lever sup-.

port and valve seat, andFig. 6 is a sectional view through the center of Fig.

In the preferred embodiment of my in` vention as illustrated, I provide a so-called air chest or chamber A, comprising verti` cally disposed facing walls 1. and 2 having spacers as 3, 4, the cap or wall 2 being attached by screws 5 so that it may be readily removed. This chamber A is, of course, of such a lengt-h and width as to suitably take care of the desired number of valve mechanisms, as will be readily understood.

A single valve mechanism B is shown comprising a plate G having a centrally disposed air port '7 formed so as to provide -a valve seat S, and above said port a pair of inwardly projecting ears 9 are formed, having concave /formations 10 for supporting the valvelever shaft. Plate 6 is secured to the inner surface of the wall 1 preferably by screws 11, the valve seat 8 projecting yinto a chamber 12 having a valve seat 13, said chamber 12 having an atmosphere duct 14 and bellows duct 15.

A valve lever 27 is provided, having a pointed shaft 25, which is sprung between the resilient armsl) and held between the concaved portions 10 in such a manner that the depending lever 27 is free to reciprocate without any lateral movement, thus doing away with guides, such as have been previously used. vAt the free end of lever 27, a valve 29 is adjustably attached b v means of a screw 30, said valve having facings preferably of leather, which act upon valve seats S and 13.

At a point preferably intermediate of the pivoted end of lever 27 and the valvesupport 30, a buffer 31 is adjustably secured, said buffer coperating with a dia-` phragm 32, which is preferably of rubber or leather, and suitably fastened over the diaphragm actuating chamber 23. Chain` ber 33 is preferably round, and a duct 3l leads therefrom to a tube extending to its tracker bar port 3G. 'A connecting duct 37 leads from the main air chamber A to each duct 34, there being a cap 3S provided with a small opening inserted inieach duct 37 to allow only a small flow of air. A tube from chamber A is also connected to the Avacuum pump to create a vacuum in chamber A in a well known manner.

It will, of course, be understood that in using my invention, the air chest is made wider than shown, and the associated bellows and valve mechanisms are staggered in accordance with well known practice.

An action-operating bellows C is suitably fastencd to the wall 1 in connection with duct 15 and is connected to a hammer action lever 16`by means of a connecting rod- 17, which is pivotally attached at its upper end and held to the bellows extension 18 by a pair of ball faced nuts 19. Each action lever 1G is pivotally secured to an arm 20, which is detachably secured to a rack or bar 2l by means of screws 22, said rack being suitably supported, preferablv by screws 23. An overhanging'portion Ztl of arm 20 carries an adjustable stop 2l,

whereby the upward travel offaction lever-*105 16 isdetermined. An adjustable buffer screw 2G is also carried by lever 16 which acts-upon the action mechanism D, as will be readily understood.

In the operation of the action, a vacuum 110 is created in the air chamber A .y suitable means, and with the music sheet covering the duct 36 a vacuum is also created in duct 34. Thus the atmospheric pressure against valve 29 tends to hold valve lever 27 in its normal or inoperative position, and therefore the bellows C is maintained open. Upon opening tracker port 36, duct 311 tends to come up to atmospheric pressure, resulting'in a pressure against diaphragm 32 by the pressure in chamber 33. Buffer 31 therefore acts upon lever 27, which causes valve 29 to normal or air chamber port seat and engage the latmosphere duct seat 13, whereby the bellows chamber is connected to the chamber A by ducts 15. `A vacuum is thus createdin the bellows chamber, allowing the atmospheric pressure to close the bellows, whereby the arm 18 rises and through connecting rod 17 and lever 1G the hammer action mechanism D is actuated. Upon closure of port 36 again, duct 35 and chamber 33l being connected to chamber A again have the pressure therein reduced so that the atmospheric pressure acting upon valve 29 through duct 14, forces the valve 29 against its seat 8 and thus the bellows chamber being connected to atmosphere through ducts 15, 14, again opens and restores the action mechanism D.

What I claim as new and desire to secure by Letters Patent is:

l. A pneumatic action for pianos comprising an air chamber, a valve plate secured to an inner vertical wall thereof, 4and having Lan air port and valve seat, a pair of inwardly projecting resilient arms for said plate disposed above the port and having facing concave portions, a valve lever having'a pointed-end shaft'supported by said concave portions whereby said lever depends opposite said port, and a valve for said port supported by said lever.

2. A pneumatic action-for pianos comprising an air chamber, a valve plate secured to an inner wall thereof, a pair of inwardly projecting arms for said plate having facing concave portions, a valve lever having a pointed supporting shaft lcarried by said concave portions, said valve plate having an air duct and a valve seat on the outer side thereof, and a valve for said seat having a valve stem projecting through said port and carried by said lever.

3. A pneumatic action for pianos comprising an air chamber having facing inner walls, a valve lever disposed within said chamber and pivotally supported at one end in said chamber, an air port through one of said walls opposite the free end of the lever, al valve carried at the free end of the lever for controlling said port, a plate secured to one of said walls for supporting said leverand having a seat for said valve, an action operating bellows connected with said port, a diaphragm on the opposite wall, an air duct whereby said diaphragm may be oscillated, and a buffer carried by said lever in operative relation with Asaid diaphragm.

4. A pneumatic action for musical instruments comprising an airehamber, a valve plate secured thereto, a valvel lever, a pointed shaft for said lever, a coperating valve and port for said lever and plate respectively, and a pair of resilient arms extending from said plate having facing concave portions for supporting said valve lever by said pointed shaft and whereby said arms may be readily sprung apart to remove said lever.

Signed by me at Chicago, county of Cook, and State of Illinois, in the presence of two witnesses.

l wrLLrAM G. BETZ.

Witnesses 'GEORGE E. MUELLER,

VILLIAM H. FEINDT.

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of Patents,

Washington, D. C.

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