US2550153A - Piano action - Google Patents

Description

April 24, 1951 s. K. KETTERMAN PIANO ACTION Filed Nov. 5, 1948 WMVk 4 a rd INVENTOR. Sylvan H. KezZerrrza/L/ Patented Apr. 24, 1951 UNITED STATES PATENT OFFICE 2,550,153 PIANO ACTION Sylvan Ketterman, Muncie, Ind. Application November 5, 1948, Serial No. 58,453

This inventionrelates to piano actions, and more particularly to an actuating mechanism and key structure for such actions which is applicable particularly to upright pianos :of the smaller sizes.

One. object of my invention is to provide a piano action and key structure which, although applicable to pianos of smaller sizes, provides playing leverage -and touch comparable to those, generally found on the large pianos.

My invention has ,for another object the provision of an action for use in small size upright pianos and whichminimizes frictional resistance to operation. 7 1

As another object, the invention comprehends the provision of an action including an actuating key and mechanism constructed and arranged so that both thehammer and key levels may be selected for a particular piano size. I

It is a further object of this invention to provide a piano action including a key and actuating parts and wherein the structure and arrangement is such that the keys are removableseparately or as a group without disturbing the rest of the action and the action parts are removable Without disturbing the keys. I

This invention also comprehends the provision of a piano action and key combination wherein the relationship of parts is such that access is convenient for tuning and adjusting.

Other objects and advantages ofthe invention will be apparent fromthe following description and the accompanying drawings "in which similar characters of reference indicate similar parts throughout the several views.

Referring to the one sheet of drawings, the single figure of the drawing is a fragmentary vertical end sectional view illustrative of the action and playing key portions of a piano embodying a preferred form of my invention.

Referring to the exemplary embodiment of my invention which is depicted in the accompanying drawing for .illustrative purposes, a hammer actuatingmechanism, which isof a structureand size recognized as practically standard in the art for .many'years, is disposed in aligned-relationship between a string In :at the rear of the piano and a key'bed 12 at the frontof the piano, below which key bed is a bottom frame 3:ccm prising the front panel of the piano case. Substantial space 'is provided between thekey bed 12 and the string '10 for the accommodation of the piano action which includes the hammer actuating mechanism. There being an action, such as that illustrated, for each string of the piano, each 1 Claim. (01. 84-240) 2 such string and action are accompanied by a key I4 pivotally supported for rocking movement in a vertical plane andrelative to a balance rail {-5 and a balance rail pin I6, in a manner well understood in the art.

Although quite well known and understood, certain parts of the hammer actuating mechanism will be specifically referred to herein for identification and reference purposes. As is usual, the hammer actuating mechanism is carried by a'ha'mmer rail l'l-and includes a hammer 18 supported for swingingmovement toward and from the string I!) by the hammer rail *I'l and having a normal position of rest against a hammer 'support rail 19. In addition to the hammer 8,"'there is a damper 20 movably supported from the rail I! by'a damper lever '22. The parts through which the hammer and damper areoperated-include a Whippen 23, jack 24, damper spring 25, back check 26, and spring rail 21; the actuation of both the hammer l8 and damper 20 being effected by limited swinging movement of the whippen 23 in a vertical plane and relative to a stationary support provided by a whippen pivot flange 28 secured to the rail ll.

The position of the hammer and its actuating mechanism are desirably selected in reference to the piano string acted upon by the hammer for optimum playing results; the level at which the hammer and its actuatingmechanism are disposed being influenced and determined'by the length of the strings. The desirable height of the" key board, on the other hand, selected for convenience in playing. The factors influencing the relative levels of the keys and their associated actions are consequentially unrelated. Also, while the desired key board level remains practically the same, regardless of the height and size of the piano, the most effective level for the action'varies with the height of an upright piano and the resultant permissible length of its strings.

In'the larger upright planes, the relative levels of the keys and actions was such that the lever portions ofthe keys on the opposite sides of the pivotal supports for those'keys were both permis sibly'qu'ite long. The key leverage, and lever arm lengths, inany instance, control certain characterist'ics of the force required for actuating the hammer and the movement of a key which is necessary for producing the necessary travel of the hammer. These factors influence What the piano players refer to as touch, as well as the ease of control exercised by the playerover the force of the hammer against the string.

Since there are various factors which are against the desirability or advisability of altering or completely revising the structure of the hammer actuating mechanism from the characteristics which have become quite standard and well known, the more modern desire for smaller pianos has brought about the need for effecting other changes to compensate for the altered position of the action in the smaller pianos, and yet preferably to provide in the smaller pianos a touch or key leverage characteristics and low friction losses comparable to those developed over a long period in the larger pianos. In addition to the foregoing, the adaptation of an action to the smaller pianos should be such that the keys are removable individually or as a complete set without distiu'bing the action, and the actions should be removable separately and without disturbing the keys. The latter considerations contribute to ease of service and tuning.

Having given consideration to factors such as those which have been discussed, I have provided a new and different key structure which, as depicted by the key [4, has rigidly connected lever portions 29 and 30 disposed in substantially right angular relationship to one another and adapted for normal disposition with the lever portions movable in a vertical plane and with the lever portion 39 extending downwardly from the key bed to a level below that of the whippen 23 in the hammer actuating mechanism. With this key structure, the lever portion 29 is manually operated and has the usual and characteristic key movement. Upon such movement, however, lever portion 39 swings about the pivot provided by the balance rail and balance rail pin 16, so that the principal component of movement of the lower end thereof is horizontal.

The movement of the whippen 23 required for actuation of the hammer l8 being generally vertical, as contrasted with the mainly horizontal component of movement of the lower end of the key lever 30, and in order to minimize friction in producing actuation of the hammer in response to movements of the key, as well as to maintain satisfactory leverage, I have provided a bell crank 32 which is interposed for rotational movement between the lower end of the lever portion 30 and a bearing 33 on the lower surface of the whippen to translate the horizontal movements of the key lever into vertical movements of the whippen. The bell crank 32 is supported for such rotational movement by a bell crank flange 34 secured to and carried by a bell crank support rail 35. Also secured to the bell crank support rail is an arm 36 which acts as a support for a key leveling screw 3! against the end of which the lever portion 30 of the key normally rests, and upon the adjustment of which the normal level or position of the key is dependent. I

The bell crank 32 has arms 38 and 39 disposed in substantially right angular relationship to one another; the arm 38 having a normal position substantially parallel to the lower surface of the whippen and the arm 39 having a normal position substantially parallel to the lever portion 30 of the key. At the projecting end, the arm 38 of the bell crank has a substantially arcuate bearing surface 40 which normally engages the bearing surface 33 on the lower surface of the whippen, and which latter bearing surface is desirably arcuate and padded. An arcuate and preferably padded bearing surface 42 is provided at the projecting end of the arm 39 facing toward the lower end of the key lever portion 30. A capstan screw 43 is carried at the lower end of 4 the key lever portion 30 at a position aligned for engagement with the bearing surface 42 on the bell crank, and is adjustable toward and from the surface of the key lever portion to effect engagement between the bearing surfaces 33 and 40 on the whippen and bell crank when both the whippen and key are in their normal positions.

Since the principal component of movement of the lower end of the bell crank arm 39 from its normal position is horizontal, as is the principal component of movement of the lower end of the lever portion by which it is actuated, there is very little relative movement between the capstan screw 43 and bearing surface 42 to produce appreciable frictional resistance to such movement. Likewise, the principal component of movement of the extending portion of the whippen is vertical and in correspondence to the principal component of movement of the extending end of the bell crank arm 38, so that there is only very slight relative movement between the whippen and bell crank bearings 33 and 40 to introduce frictional loss at that point in the mechanism. The substantially arcuate curvature of the engaging bearing surfaces on the capstan screw, bell crank and whippen provides for relatively free rolling movements between those surfaces.

In the disclosed embodiment of my invention, the lengths and relative proportions of the lever portions of the keyl i are such that the key movements and forces for actuating the hammer simulate those of a large piano in which the action is placed at a considerably higher level relative to the keys. Also, in the disclosed embodiment, the effective lengths of the arms 38 and 39 on the bell crank are such that they do not materially alter the characteristic movements and forces by virtue of their interposition between the key lever portion and the whippen. Furthermore, the bell crank 32 being disposed below the hammer actuating mechanism and to the rear of the key lever portion 30 and not attached to either the key lever portion or whippen, the bell crank does not interfere with the removal or adjustments of either the key or the hammer actuating mechanism. With the key in the form and position disclosed, it is also noteworthy that both the key and action are selectively removable without interference to one another.

' While I have illustrated a preferred embodiment of my invention, many modifications may.

be made Without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States,- is:

In an action for a piano, the combination comprising a substantially rigid key bed having a balance rail directly mounted thereon, a hammer actuating mechanism-including a whippen having a bearing surface on the bottom thereof, a key supported on said balance rail at a level above that of the whippen for pivotal movement relative to the balance rail, said key including a lever arm portion which comprises a substantially rigid continuation of the key extending downwardly at substantially a right angle to the rest of'the key at a position between the balance rail and the hammer actuating mechanism and terminating below the whippen,

5 the length and disposition of said lever arm portion being such that the principal components of movement of the end thereof below the whippen are horizontal when the key is moved, a capstan screw adjustably mounted at the lower end of the lever portion below the whippen, a bell crank support rail, a bell crank movably supported on said bell crank support rail for translating movements of the capstan screw to the bearing surface of the whippen to efiect actuation of the hammer mechanism in response to movements of the key, an arm extending from the bell crank support rail to a position adjacent the lever portion of the key, and a leveling screw adjustably carried by said arm and having an end normally engaging said lever 5 arm portion on the side thereof opposite the capstan screw.

SYLVAN K. KETTERMAN.

REFERENCES CETEI) The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,226,877 Schulze Dec. 31, 1940 FOREIGN PATENTS Number Country Date 446,730 Great Britain May 5, 1936 477,242 Great Britain an Dec. 24, 1937

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