US2963934A - Piano action - Google Patents

Description

United States Patent 6) "cc 2,963,934 PIANO ACTION Ewald William Hucke and Harmon G. Mitchell, Rockford, lll., assignors to Wood & Brooks Company, Rockford, 111,, a corporation of Illinois Filed Mar. 12, 19,58, Ser. No. 720,891

1 Claim. (Cl. 84-243) This invention relates to piano actions of the type in which a hammer is projected against a string in the endwise movement of a key actuated jack. The latter is en gageable at its free end with a knuckle formed on the butt of the hammer shank adjacent to but offset from the shank fulcrum. As the hammer approaches the string, the jack encounters a regulating button and, in the continued motion of the key, is rocked to slide the jack tip oif the knuckle preparatory to back checking the hammer. Then, as the pressure is released, the jack tip is pushed back beneath the knuckle in preparation for the next key motion.

The jack usually is made of wood and its free end is bevelled to provide a surface for engaging the arcuate knuckle surface. The invariable practice heretofore has been to form the knuckle surface from a covering of special and relatively costly buckskin in order to provide greater resistance to wear during the repeated sliding of the jack oif the knuckle while the two engaging surfaces are under substantial pressure.

The principal object of the invention is to provide a new and improved covering for the butt knuckle which produces a better action between the jack and the butt knuckle, which has substantially better wear characteristics and dimensional stability than buckskin and which, at the same time, is considerably less costly.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which Figure 1 is a fragmentary elevation of a piano action embodying the novel features of the present invention.

Fig. 2 is a fragmentary elevational view of a portion of the action and shows the parts in a different position.

Fig. 3 is an enlarged fragmentary perspective view of the jack.

As shown in the drawings for purposes of illustration, the invention is embodied in a vertical grand piano comprising a plurality of keys 10, only one of which is shown, fulcrumed in the usual way on a balance rail (not shown) supported by a key bed 11. At its rear end, the key carries a capstan screw 12 and, in the released position shown, rests against a pad 13 on the bed.

The action proper is of the general design used in upright pianos and includes a metal frame bracket 14 rigidly' supported in the usual manner by the string plate 15. Pivotally mounted on a main rail 16, which is secured to the bracket 14, is a hammer 17 arranged to be projected against a string 18 by the key 10. In the released position, the hammer shank 19 rests against a cushion 20 on a hammer rail 21 mounted on the bracket 14. The butt 22 of the hammer is formed with a knuckle 23 which is covered by a pad 24 and is engaged eccentrically of the hammer pivot 25 by the upper end of a jack 26 pivoted at 27 on a whip 28. The latter is disposed in a generally horizontal position and is supported at its rear end from a flange 29 on the rail 16 so as to swing about a fixed pivot 30.

2,963,934 Patented Dec. 13, 1960 As the whip 28 is swung upwardly from the idleposition' illustrated in Fig. 1, the jack 26 is. raised thereby projecting the hammer forwardly against the string. During this endwise movement of the jack and as the hammer approaches the string, an arm. 31 on the. jack strikes a regulating button 32 which. rocks the jack about; its

fulcrum 27 and slides the tip 33 of the jack off the knuckle 23 .as, shown. in Fig. 2 preparatory to back che cking the hammer. The whip carries the; usual back check 34 which coacts in a well known manner with a catcher 35 carried by the butt 22. The action also, includes a string damper 36 which, is on the upper end of a lever 37 fulcrumed on the. rail 16 and which operates in a concnt q al, m nn r enga h s ng upo release. of the key, the damper being urged toward the string by a wire spring 38 acting between the rail and the lever and swung away from the string by a spoon 39 upstanding from the rear end of the whip.

Motion of the key 10 is transmitted to the hammer 17 through a linkage 40 which includes a generally horizontal lever 41 fulcrumed at its forward end to a stationary part 42 rigid with the bracket 14. A downwardly extending link 43 is pivotally connected at one end to the rear end of the lever and at its opposite end to the forward end of the whip 28. Intermediate its ends the lever is formed with a padded surface 44 which engages the capstan screw 12 so that, when the key 10 is depressed, the lever 41 swings clockwise about its fulcrum thereby tuming the whip counterclockwise and projecting the hammer.

In an action of the above character, it is important that the butt knuckle 23 be provided with a cover 24 whose surface permits the jack 26 to slide off the knuckle easily even though the two engage under substantial pressure and which, at the same time, resists Wear. Heretofore, the standard practice has been to cover the knuckle with a relatively expensive imported buckskin. Great care has been taken in sorting and cutting the buckskins to obtain surfaces of the desired texture, density and thickness.

We have discovered that the performance of the action may be greatly improved and the life of the butt knuckle cover 24 materially increased by forming this cover from a material commonly known as precision felt instead of buckskin. Moreover, the use of such felt results in a substantial reduction in the costs of both the material and labor involved in obtaining and preparing the cover. This is for the reason that the felt is readily available domestically and as purchased is uniform in texture, density and hardness.

With actions employing buckskin covers 24, the latter wear and it is necessary to adjust the action to compensate for this wear every 200,000 blows of the hammer 17. In contrast, it has been discovered that the felt has a much greater dimensional stability. With felt, the first adjustment is not required until after 300,000 blows and the next one is not needed until there have been two million blows. Thereafter, the stability is even greater, adjustment being required after about ten million blows.

It is believed that these improved results are due to the fibrous structure of the felt. During the initial use of the action, the felt becomes compacted and the wool fibers form a polished, slippery surface from which the tip 33 of the jack 26 can escape more readily. On the other hand, buckskin is a grainy material and does not become polished. Instead, it continues to wear oif at a uniform rate.

Another factor apparently contributing to the better performance of the felt is the coaction of the latter with the graphite which usually is placed on the jack tip 33. Not only does this graphite result in a polishing of the tip but it also transfers to the felt and effects a polishing action on the felt surface. No such polishing of the surface of the covering 24 occurs when using buckskin. Because of the slippery surface formed on the felt, the force required for the jack 26 to escape from the butt is materially reduced.

It will be observed that a piano action employing a cover 24 of precision felt has marked advantages over one using a buckskin cover. Less force is required for the jack 26 to escape from the butt knuckle 23, the cover has much greater dimensional stability so that the action need be adjusted for wear of the cover only a few times during the life of the piano, and the costs of the cover material and in the labor involved in preparing it are greatly reduced.

We claim as our invention:

In a piano action, the combination of a frame, a'hammer adapted to be projected against 'a string, an elongated shank supporting said hammer and having a butt pivotally connected to said frame, a jack having a tip engaging a portion of said butt eccentric of the pivot, said jack being adapted for connection to a piano key and mounted for endwise movement to turn said shank about said pivot and project said hammer toward the string, means for rocking said jack as the hammer approaches the string to slide said tip off said butt, and a pad made of precision felt and covering said butt portion to engage said jack tip and facilitate sliding of the tip off said butt.

References Cited in the file of this patent UNITED STATES PATENTS 625,128 Steinert May 16, 1899 668,424 Steinert Feb. 19, 1901 679,485 Steinert July 30, 1901 772,683 Steinert Oct. 18, 1904

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