US2767608A - Vibrator exciting action - Google Patents

Description

United States Patent VIBRATOR EXCITING ACTION Benjamin F. Miessner, Harding Township, Morris County, N. J., assignor to Miessuer Inventions, Inc., Harding Township, Morris County, N. 1., a corporation of New Jersey Application June 5, 1952, Serial No. 291,830

6 Claims. (Cl. 84-236) This invention relates to a motion-transmitting mechanism and more particularly to a vibrator-exciting action including novel means for preventing spurious excitation of the vibrator for a single key depression while affording sensitive touch-responsive control of the vibrators vibration amplitude and high speed repetitions of key actuation.

In a broad sense, the present invention is directed to a novel mechanical arrangement for preventing rebounding of a driven member relative to a driving member in a mechanism of the type wherein the driven member is directly and positively set into motion by the driving member. In a specific sense, the invention is directed to a novel vibrator-exciting action, of the direct drive class, including novel means for completely absorbing the kinetic energy of the striking hammer as it rebounds from the vibrator.

Although the herein-included illustrations and description are limited to vibrator-exciting actions, those skilled in the art will have no difficulty in applying the novel mechanisms to other uses.

In my co-pending United States patent application Serial No. 376,543 filed August 26, 1953, I disclose a novel vibrator-exciting action including a frictional resistance means for dissipating the rebound energy of the striker hammer said means comprising a first member spaced from the playing key in fixed position, and a second member carried by the playing key, at least one of said members having a relatively high coetlicient of friction and the two members adapted for sliding pressure contact to an extent depending upon the motional velocity imparted to the playing key.

The present invention is directed to other novel arrangements for absorbing such rebound energy of the hammer while affording high speed repetitive actions of the playing key and sensitive touch-responsive control of the vibrators vibration amplitude.

An object of this invention is the provision of a motion-transmitting arrangement of the type comprising a driven and a driving member, and including an intermediate member carried by the driving member and interposed between the driving member and the driven member, said intermediate member being frictionally secured to the driving member and movable relative thereto a distance proportional to the velocity of the driving member.

An object of this invention is the provision of a keyactuated vibrator-exciting action including novel means carried by the playing key and adapted to absorb the kinetic energy of the striker hammer as it rebounds from the vibrator.

An object of this invention is the provision of a directacting vibrator-exciting action including, in combination, a limitedly movable playing key, a weight frictionally carried by the key and movable relative to the key in proportion to the key velocity and a pivoted hammer movable by the weight, said hammer adapted to strike the vibrator.

An object of this invention is the provision of a vibrator-exciting action comprising a pivotally-mounted playing key, a mass carried by the playing key and adapted for limited movement relative to the key, frictional means affording relative movement of the mass to an extent depending upon the velocity of movement imparted to the key, a pivoted hammer moved by the key to a relatively small spacing from the vibrator and thereafter moved by its own momentum to strike the vibrator and rebound therefrom, said rebounding movement of the hammer returning the mass to its initial position relative to the key.

An object of this invention is the provision of a vibratorexciting action comprising a pivotal-ly-mounted playing key, means limiting the extent of the pivotal movement of the key, a weight carried by the rear end of the playing key and adapted for limited movement relative to the key, frictional means in surface contact with the weight and tending to prevent relative movement of the weight with respect to the key, means for adjusting the pressure between the frictional means and the Weight, a pivotally-mounted playing hammer having a butt in contact with the weight, said butt moving out of contact with the weight when the key reaches the limit of its pivotal movement and moving into contact with the weight as the hammer rebounds from the vibrator.

These and other objects and advantages will become apparent from the following description when taken with the accompanying drawings illustrating several embodiments of my invention. It is to be understood the drawings are for purposes of illustration and are not to be construed as defining the scope or limits of the invention, reference being had for the latter purpose to the appended claims. In the drawings wherein like reference characters denote like parts in the several views:

Figure 1 is a longitudinal, section taken through a vibrator-exciting action made in accordance with one embodiment of this invention and showing a tuned-reed vibrator;

Figure 2 is a fragmentary top plan view, drawn to an enlarged scale and showing the rear end of the playing y;

Figure 3 is similar to Figure 1 and key in the depressed position;

Figure 4 is a transverse, sectional view taken along the line A-A of Figure 2, drawn to a still further enlarged scale, showing grooved side walls on the shank of the movable weight for the purpose of increasing the frictional resistance to relative movement between the weight and the playing key;

Figure 5 is a fragmentary, plan view, similar to Figure 2, showing another embodiment of the invention;

Figure 6 is a side elevation of the arrangement shown in Figure 5;

Figure 7 is a longitudinal, sectional view taken along the line BB of Figure 5;

Figure 8 is a fragmentary, plan view showing a variation of the Figure 5 construction;

Figure 9 is a fragmentary, side elevation showing another embodiment of the invention;

Figure 10 is a transverse, sectional view taken along the line C-C of Figure 9 and drawn to an enlarged scale;

Figure 11 is similar to Figure 10 and showing an arrangement for adjusting the frictional pressure between the relatively movable weight and the key;

Figure 12 is a fragmentary, side elevation similar to Figure 9 and showing another embodiment of the invention;

Figure 13 is a top plan view of the playing key shown in Figure 12, and

showing the Figure 14 is a longitudinal, sectional view taken along the line D-D of Figure 13.

Reference is now made to Figure 1, wherein there is shown a key frame, or base it carrying a resilient stop 11, a balance rail 12 supporting a fulcrum pad 13, a keyguide pin 14, a front guide pin 15 and a down-stop pad 16. The playing key K is provided with a tapered hole 17 afiording pivotal movement of the key, about the guide pin 14, in response to a depression force applied to the front end of the key. The key also includes a guide slot 13, cooperating with the pin 15, and a top piece 19. Those skilled in this art will understand that the construction thus far described follows conventional practice, the tey being shown in its normal, at rest position. in conventional practice, the rear end of the playing key carries suitable weights which unbalance the key so that it will return to its normal position upon removal of the finger pressure from the playing key surface 20. Such weights are not required in my construction as my novel frictional means, for absorbing the rebound energy of the hammer, is carried by the rear end of the playing key and provides the usual 1-3 ounce unbalance of the key.

The hammer-rebound, energy-absorbing device comprises a member 22, made of metal such as lead, that is pivotally secured to the playing key by the felt-hushed pin 23. As shown in the fragmentary plan view of Figure 2, the weight 22 has a reduced-thickness shank 29 disposed between the parallel arms 50 defining a slot formed in the rear of the key. The side walls of the key slot are covered with thin, surface friction members 24, 25, such as leather, rubber, felt, resin-impregnated leather, or the like, said members being cemented to the key arms. It may here be pointed out that the strip 25 serves as a stop establishing the normal, down position of the weight 22. The free end of the weight 22 has a width corresponding substantially to that of the playing key and a reduced-thickness extension that has secured thereto a hammer-butt pad 26, preferably of visco-elastic material, and the total mass of this member is so chosen that it provides the necessary, gravity, down-biasing force on the rear end of the key. Further, the width of the slot in the key, and the thickness of the friction members 24, are so chosen, with respect to the weight of the member 22, that when the weight is pivotally moved about the pin 23 the surface friction between the members 24 and the shank of the weight 22 is suflicient to retain the member 22 in such displaced position.

The described arrangement is satisfactory for fulfilling the purposes of this invention. However, should alight, biasing force be desired to aid in returning the weight 22 to its normal position, this can be provided by a thin leaf spring 27 secured to the key as by the screw 28, and overlying the shank portion of the weight. Alternatively, the spring may be soldered to the upper surface of r the weight shank in which case the spring serves as a hinge for the weight and the pin 23 may be omitted.

Positioned to the rear of the playing key is a hammer rail 39, secured to the base 10 in any suitable manner, and. a flange 31 that is secured to the rail 30 by screws 32. A hammer butt 35 is pivotally secured to the flange 31, by a felt-hushed pin 36, and carries the hammer stem 37 to which is attached a felt-covered head 38 adapted to strike the vibrator here shown as a vibratory reed 40. When the outer end of the playing key is depressed, the pad 26 drives the hammer butt upwards until the forward end of the hammer head reaches a position indicated by the letter X on the are a, after which the hammer moves under its own momentum to strike the vibrator 4i) deflecting it to the left. At this point all of the hammers kinetic energy has been conveyed to the reed where most of it is stored momentarily by the reeds compliance. During the time, when hammer is moving under its own momentum, the hammer butt 35 is out of contact with the pad 26; the described arrangement being brought about by reason of the playing key striking the noise-silencing pad 42 carried by a fixed rail 43 that extends in spaced position across the playing key. The normal spacing between the stop pad 42 and the upper surface of the playing key is such that a direct contact between the hammer butt 35 and the driving pad 26 exists only until the forward edge of the hammer head reaches the indicated point X in its arc of travel, the point X being somewhat further away from the reed than its maximum hammer-ward vibration amplitude. Thus, there is brought about an abrupt termination of the key motion at a point where the hammer will continue its motion to strike the vibrator. Upon such abrupt termination of the key motion, the weight 22, having momentum, or kinetic energy, epending on the overall velocity of key motion, continues its upward motion, relative to the playing key, until its energy has been spent in overcoming the frictional resistance between the pads 24 and the shank of the Weight. The weight remains in this raised position until the rebounding hammer butt again comes into contact with the pad 26. If the key has remained depressed throughout the described operating cycle the kinetic energy of the rebounding hammer is absorbed in overcoming the frictional resistance between the pads 24 and the weight shank and in downwardly accelerating the weight as the weight is returned to its normal position with respect to the key. When the weight is so returned to its normal position, while maintaining the front end of the key depressed, the hammer head is disposed to the right of the point X where it can not interfere with the reeds vibration, the dotted line indicating the maximum excursion of the reed.

t will be apparent that the velocity imparted to the playing key determines both the magnitude of the hammer rebound energy and. the relative displacement of the frictionally-restrained weight 22-. it is not at all critical to adjust the frictional factor, between the pads 24 and the weight, so that the energy required to return the weight to its normal position absorbs the e tire hammer rebound energy whereby spurious excitation of the reed, at high-velocity key depression and hold down, is entirely eliminated. At the same time, the structure described, having no escapernents or delicately-adjusted limiting devices as in conventional actions, affords a maximum repetitive speed of attack and provides an extremely sensitive touch-responsive control of the vibratc-rs vibration amplitude.

Obviously, any dense, solid mate ial may be used for the frictionally-restrained weight, lead being merely mentioned because of its high density.

The amount of frictional resistance provided by the pads against the shank of the weight may be increased by grooving, or serrating, the vertical surfaces of the shank which are in sliding pressure contact with the Such construction is shown in Figure 4 which is a transverse, sectional view such as would be ta along the line AA of Figure 2, and drawn to ar. enlarged scale. Here the spaced arms of the playing key are identified by the numerals 59. The friction pads 24 are cemented to the arms '50 and contact the serrated sides of the shank 51 of the weight. Preferably, the grooves, or serrations, should be radial about the pivot axis of the rotatable Weight and the direction of the t h can be downward or upward to provide a hi im frictional resistance to downward, or upward movement, respectively, of the weight relative to the key. The pad' 24 may also be impregnated or coated with a suitable, stable, frictional material, preferably of a gummy type, to increase the sliding friction factor between the pad and the weight.

Reference is now made to Figures 57 showing a construction wherein the amount of frictional resistance between the friction pads and the shank of the movable weight is adjustable. Figures 5 and 6 are fragmentary top plan and side elevation views respectively, and Figure 7 is a longitudinal, sectional view taken along the line 13-8 of Figure 5. A thin leaf spring 60 is soldered to the top surface of the shank 61 of the weight 62 and is secured to the playing key K by the screw 63. As in the previously described embodiment of the invention, the weight shank is in frictional contact with the friction pads 24 secured to the inner walls of the key slot, and the pad 25 serves as the down stop defining the normal position of the weight with respect to the key. It is apparent that the leaf spring 60 forms a hinge affording limited, rotational movement of the weight 62 relative to the key. The shank 61 is provided with an arcuate slot 64 defined by radii of curvature about the pivot point of the weight, as indicated by the arrow r on Figure 7. A screw 65 passes through alined clearance holes in the forward arm of the playing key, the friction pads 24 and the arcuate shank slot 64, said lscrew being threaded into the hole in the rear arm of the key. The diameter of the screw 65 is less than the width of the arcuate slot 64 from which it will be clear that the screw itself does not hinder the rotation of the weight relative to the key. However, by tightening or loosening this screw the pressure of the friction pads 24 against the sides of the shank 61 may be regulated as desired. This frictional pressure should be such that the weight 62 moves upward only about i of an inch at its rear end for the strongest key blows.

It is pointed out that for best operation of the action the angular moment of inertia of the weight, and the frictional resistance of the pads against the weight shank, should be matched to the angular moment of inertia of the particular hammer mechanism. Other weights may be added to the rear end of the playing key to regulate the static unbalance of the key about its fulcrum. Alternatively, a biasing spring may be used for this purpose.

It is evident, from the above described operation of the two embodiments of my invention, that I have provided an entirely new, extremely simple and highly elfective vibrator-exciting action for direct hammer drive by the playing key without the use of intermediate, complex escapements, back-check and repetition apparatus which has been standard practice in this art for some 200 years. It is further evident that there are no limiting factors cffecting the speed of striking repetition or shallowness of key depression since the hammer is always operable by the key at any position of the key throughout its operative down stroke.

In the Figures 17 embodiments of my invention I have shown a slot in the rear end of the playing key and a weight having a reduced-thickness shank disposed within such slot. Obviously, this construction can be reversed as shown in Figure 8 which is a fragmentary plan view similar to Figure 2. However, here the weight 62 has a slot provided in its inner end forming the arms 67, and the rear end of the key K has a reduced-width tongue 68 disposed within such slot.

The common feature of the constructions shown in Figures 1-8 is the pivotal mounting of the weight on the playing key. The novel operation of my vibrator-exciting action is not limited to such specific arrangement as will become apparent from the Figures 9-14 embodiments of the invention.

Figure 9 is a fragmentary, side view of a vibrator-exciting action wherein the mass that is frictionally movable relative to the key K comprises a rectangular weight 70, made of a suitable metal such as lead, disposed over the tongue 71 that is formed as an integral part of the key. As shown in Figure 10, the surfaces of the key tongue 71 have cemented thereto a rectangular friction pad 72 made of felt, leather or etc. While the friction pad is shown as a unitary, rectangular member it can be formed more conveniently by four flat pads individually cemented to a surface of the tongue 71. Secured to the upper surface of the weight is a visco-elastic pad 73 that is in direct contact with the butt 35 of the pivotally-mounted hammer. As shown in Figure 9, the parts are in the normal, at rest position.

When the front end of the playing key.

is depressed, the hammer butt is rotated directly by the rear end of the playing key until the hammer head is spaced a small distance from the vibrator as has been described with reference to Figures 1 and 3. At this point, pivotal movement of the playing key is terminated abruptly by the thin stop pad 75, carried by the fixed rail 76, and the hammer continues under its own momentum to strike the vibrator and rebound therefrom. During the time when the hammer buttt is out of contact with the driving pad 73 the momentum of the weight 70 causes it to move upward relative to the now stationary playing key. It will be apparent the extent of the upward movement of the weight 70, relative to the key, will depend upon the frictional resistance between the inner, vertical surfaces of the weight and the contacting surfaces of the friction pads and the key-depression velocity. As the hammer butt re-established contact with the pad 73, upon rebound of the hammer from the vibrator, the kinetic energy of the hammer assembly is absorbed in driving the weight 70 downwardly to its initial position relative to the key thereby effectively eliminating hammer rebound toward the vibrator. The friction pads carried by the top and bottom surfaces of the key tongue prevent click noises as the weight moves relative to the key and lateral movement of the weight may be limited by suitable pins 77 passing through the tongue.

The amount of frictional resistance between the relatively movable weight and the cooperating friction pads may be made adjustable by forming the weight in a U-shape. Such arrangement is illustrated in Figure 11 wherein the spacing between the legs of the U-shaped weight 70' is adjustable by tightening or loosening of the screw 78.

Another embodiment of my invention is illustrated in Figures l2l4, Figure 12 being a fragmentary side elevation similar to Figure 9, Figure 13 being a top view of the playing key and hammer-rebound absorbing weight, and Figure 14 being a longitudinal sectional view taken along the line DD of Figure 13. In this construction, the rear end of the playing key is provided with a bore in the top surface, and the bottom and side walls of the bore are lined with friction pads 80, 81, respectively. The bore is intersected by a vertical, longitudinally-extending slot 82 whereby the pressure of the circular friction pad 81, against the weight 83, may be adjusted by tightening or loosening the screw 84. As shown in Figure 14, the bottom of the weight 83 includes a threaded hole accommodating the up-stop screw 85 which passes through clearance holes in the friction pad 80, the lower surface of the key and the visco-elastic pad 86, the later being secured to the key as by cement. From the above description of the Figure 9 embodiment of the invention, it is clear that the weight 83 will move upwardly, relative to the playing key, when the key movement is abruptly terminated by the visco-elastic stop 75, the extent of such weight movement depending upon the velocity imparted to the key and the frictional resistance between the weight and the contacting friction pad 81; the maximum displacement of the weight relative to the key being determined by the setting of the stop-screw 85. Such upward movement of the weight occurs during the period when the hammer butt 35 is out of contact with the viscoelastic pad 87 secured to the top surface of the Weight, that is, when the hammer is moving toward the vibrator under its own momentum. Rte-establishment of contact between the hammer butt and the pad 87, upon rebound of the hammer from the vibrator, forces the weight 83 back to its original, normal position and the kinetic energy of the hammer mechanism is absorbed in overcoming the friction between the weight and the encircling friction pad. While I have shown a cylindrical weight 83 it will be apparent other forms may be used as, for example, a rectangular weight having a relatively longer length longitudinally of the key, whereby the mass of the weight may be increased, as desired.

The herein-disclosed embodiments of my invention all operate on the same broad principle, namely, a static resistance'between the playing key and a mass movable therewith is converted into a dynamic resistance by the down stroke velocity applied to the front end of the key, resulting in a displacement of the mass relative to the key to an extent directly related to the key velocity. The forward and rebound motion of the hammer mechanism is likewise directly related to the key velocity and the energy required to return the mass to its original position, relative to the key, completely absorbs the rebound energy of the hammer mechanism. For low key velocities the weight moves only a relatively small distance relative to the key, for large key velocities such Weight movement is proportionally larger. The actual work to be done in moving the frictionally-restrained weight is automatically metered by key down-stroke velocity since the displacement of the weight, at a constant friction factor, is determined by the momentum of the weight. Thus, for all key velocities, the weight has set up for it a returnmotion path which is just right for the absorption of the kinetic energy of the hammer during its initial rebound cycle from the vibrator.

While I have described my invention with specific reference to vibrator-exciting actions the principle of rebound suppresison herein disclosed will find numerous applications in other fields. In a broad, mechanical analogy, the key represents any driving member and the hammer the driven member. Interposed between these two members is an intermediate member carried by the driving member said intermediate member having a definite down stop on the driving member and being movable relative to such driving member. The intermediate member dri'es the driven member and develops momentum which carries it away from its normal down stop position when the driven member loses contact with it. When the driven member returns into contact with the intermediate member its energy is absorbed in overcoming the friction between theintermediate member and the driving member as the former is returned to its normal, down stop position with respect to the driving member.

I have explained how the effective frictional, or motionopposing, force, between the weight and the playing key, may be increased by coating, or impregnating, one or both of the relatively-slidable surfaces with a suitable tacky material and how thefriction factor may be adjusted by means of the pressure-adjusting screws. I have found the friction pads and the adjusting screw-s advantageously may be omitted in certain vibrator-exciting actions.

Reference is again made to Figures 1 and 2, although the following remarks apply to all of the illustrated embodiments of the invention. The friction pads 24 may be omitted and the frictional, motion-opposing force (opposing relative movement between the key K and the weight 22) provided by coating the co-acting surfaces of the weight shank 29 and the key arms 50 with a tacky substance falling into the general category of nonfiuid grease. Such substance must remain relatively stable with time, temperature and humidity so that the friction action remains substantially uniform. Various sticky, synthetic resins are available for this purpose. A specific example of one substance satisfactory for the particular purpose of this invention, is a tree-bonding product, sold under the trade-name of Tangle Foot, which retains its tacky characteristic between a range of -110" F. Such tacky substance is applied to the adjacently-disposed, relatively-slidable surfaces of the weight and playing key and is effective to suppress harnmer rebound as has been explained with reference to the friction pads shown in the various embodiments of the invention. Surprisingly, the hammer-rebound, suppressing action is effective, to an entirely practical extent, even though the relatively slidable surfaces of the weight and key are free of actual surface contact pressure. Specifically, the surfaces ofthe weight shank 29 can actually be spaced from the adjacent surfaces of the key arms 5.0 and such space filled with the tacky substance which acts .as the friction element. 7 When the rotational movement of the key isterminated abruptly by the stop pad 42, the momentum of the weight 22 causes it to move upwardly relative to the key. At the time the weight is moved relative to the key the hammer mechanism is moving, under its own momentum to strike the vibrator and rebound therefrom. The'kinetic energy of the rebounding hammer butt is absorbed in returning the weight to its normal, down stop position relative to the key, even though the outer end of the playing key remains depressed.

One advantage of the arrangement using only the grease substance as the friction element lies in the fact that the weight will return to its normal, down stop position on the key by gravity action alone. More specifically, if the hammer mechanism be removed and the playing key struck, the weight will be moved upward with respect to the key and said weight will slowly return to its normal downstop position, by gravity action, in about one (1) second. Thus, the weight always returns to its normal position following each key stroke thereby assuring a uniform action. In the previously-described embodiments of the invention, employing the friction pads, rapid, varying-pressure key depression occasionally result in the weight being disposed somewhat up from its normal, down stop position so that a succeeding key stroke first causes the weight to move downwardly relative to the key. While such reverse action of the weight movement occurs infrequently and does not seriously aifect the functioning of the vibrator-exciting action, the use of the sticky, grease substance in place of the friction pads .does provide absolute uniformity of operation.

Having now described my invention in accordance with the patent statutes what I desire to protect by Letters Patent of the United States is set forth in the following claims.

I claim: 7

1. A vibrator-exciting action comprising a pivoted playing key having a bore at the rear end and a longitudinal slot intersecting the bore; a friction member lining the wall of the bore; a weight disposed within the bore and in surface contact with the friction member; means limiting the extent of movement of the weight relative to the key; a stop limiting pivotal movement of the key; a visco elastic pad carried by the weight, and a pivoted hammer movable by the visco-elastic pad to a small distance from the vibrator and thereafter movable under its own momentum .to strike the vibrator and rebound therefrom.

2. The invention as recited in claim 1, wherein the meanslimiting the extent of movement of the weight comprises a headed stud having a threaded shank passing through a clearance hole in the key and into a threaded hole in the weight.

3. In a key-operated vibrator-exciting action, an element carried by the key for movement therewith to a certain position upon operation of the key and further movable relative to the key whereby to be subject to further displacement beyond said position in response and in proportion to its own momentum acquired during key operation, a hammer propellable by said element to strike the vibrator, the ham er in rebounding from the vibrato-r while the key remains operated impinging on said element and moving it back from said further displacement, and damping means comprising cooperating portions one secure with respect to said element and the other secure with respect to the key, responsive to the relative movements of said element and the key, for dissipating the energy of such relative movements.

4. In a key-operated vibrator-exciting action, an ele ment having a normal relationship to the key and moved therewith upon operation thereof and further movable relative to the key whereby to be subject to displacement from said normal relationship in response and in proportion to its own momentum acquired during key operation, a hammer propellable by said element to strike the propellabie by the key to strike the vibrator, an element vibrator, the hammer in rebounding from the vibrator coupled to, and moved, by the hammer in its rebound while the key remains operated impinging on said element from the vibrator While the key remains operated, and and restoring it to said normal relationship, and damping brake means, biased into continuous engagement with means comprising cooperating portions one carried by 5 said element and frictionally moved against by said elesaid element and the other carried by the key, responsive ment throughout said movement of the element by the to the relative movements of said element and the key, hammer, for absorbing the energy of the movement of for dissipating the energy of such relative movements. the element by the hammer.

5. In a key-operated vibrator-exciting action, an element mounted in the action for movement by the key to a 10 References Cited in the file of this Patent certain position upon operation of the key and further UNITED STATES PATENTS movable relative to the key whereby to be subject to further displacement beyond said position in response and g g ii 3 in proportion to its own momentum acquired during key 316023 o 1885 operation, a hammer propellable by the key to strike the 15 Q6 5 vibrator, the hammer in rebounding from the vibrator 1 Gilmore 1910 while the key remains operated coupling to said element 2271460 Mlessner 1942 and restoring it from said further displacement, and means, 2474462 BrFWer June 28, 1949 biased into continuous engagement with said element and 2,535,503 Mlessnel' 1950 frictionally moved against by said element throughout its 20 said further displacement and restoration therefrom, for FOREIGN PATENTS braking said further displacement and restoration. 358,344 Germany Sept. 11, 1922 6. In a key-operated vibrator-exciting action, a hammer 422,022 Germany May 15, 1926

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