This invention relates to hammer actions for stringed musical instruments.

It is an object of the present invention to provide an action which shall be simple in construction, which shall fulfill all of the usual requirements of such actions with respect to freedom of rebound, rapidity of repetition and so forth, but which shall also have inherent operating advantages of value which are not provided by the usual hammer actions. For example, it is an object of the invention to provide an action having greater smoothness and ease of operation, an action which will provide improved tone quality, an action which will permit bigger fortissimos to be obtained, and an action which will provide improved control for pianissimo playing. It is also an object of the invention to provide greater ease and permanence of adjustment than is usual in ordinary piano actions.

Other objects and advantages of the invention will appear hereinafter.

A preferred embodiment of the invention selected for purposes of illustration is shown in the accompanying drawings, in which,

Figure 1 is a section through an. action, showing one unit thereof in elevation, the parts being shown in normal rest position.

Figure 2 is a similar view showing the position of the parts as the hammer approaches the string, and in broken lines, showing the hammer in contact with the string.

Figure 3 is a similar view showing the position of the parts after the rebound of the hammer, but before release of the key.

Figures 4, 5 and 6 are enlarged detail sectional views of the pin joints, and

Figure 7 is a. section on the line 7--7 of Figure 1.

Referring to the drawings, the individual units of the action are each mounted, in the usual manner, upon the hammer flange rail 1 which is supported at intervals along its length by the brackets 2, the hammer flange 3 of each unit being secured to said rail by means of screws 4. Pivotally mounted on the flange 3 by means of pin joint 5 is a substantially L-shaped member 6 which may be called the driver, and pivotally mounted on said driver by means of pin joint 7 is the hammer shank 8 carrying hammer 9.

Also pivotally connected to the driver 6 by means of pin joint 10 is a member 11 which may be referred to as the upper knuckle link, and pivotally connected to said upper knuckle link by means of pin joint 12 is a lower knuckle link 13. For convenience, the pin joint 12 may be referred to as the knuckle joint.

The lower knuckle, link 13 is operatively connected with the key 14 by means of pin joint 15, flange 16, spring clip 17, and capstan screw 18, the capstan permitting easy adjustment between the key and knuckle links, and the clip 17 providing a convenient connection which may be readily attached or detached when desired.

Secured to the brackets 2 are brackets 20 carrying a transverse member 21 which may be called the driver stop. Preferably this member is channel shaped to receive a strip of silencing material 22 such as felt or bushing cloth and is so located as to be in the operative path of the driver stop screw 23 carried by the depending arm of the driver 6; which is adjustable to limit the travel of the driver 6 to any desired extent. Preferably the said screw is so adjusted as to permit the driver to carry the hammer to a position closely adjacent the string (as illustrated in Figure 2) as for example, within 1/16" of the string, and preferably even closer, but may be otherwise adjusted if desired.

In the normal position of rest illustrated in Figure 1, the knuckle joint 12 is urged, under the influence of repetition spring 24, to a position such that it is slightly in front of the line of centers connecting the joints 10 and 15, but is prevented from moving further in this direction by the knuckle stop 25, comprising abutting faces having a strip of silencing material therebetween.

The point of connection of the spring 24 to the knuckle member 13 may be located in such position as to provide any desired rapidity of return of the knuckle links to normal position after the joint is broken as hereinafter described.

Secured to the front face of knuckle link 11 is a strip of silencing material 26, mounted in position to lie in the operative path of knuckle breaker 27 carried by the driver 6. The knuckle breaker is preferably an adjustable screw and is adjusted in such manner that as the driver swings on its pivot 5 the knuckle breaker will move into contact with the pad 26 shortly before driver stop screw 23 comes into contact with driver stop 22, the result being that the knuckle joint is pushed to the rear of the line of centers connecting joints 10 and l5 for reasons which will be apparent hereinafter.

In order to provide an action of great durability, the pin joints have been carefully constructed. Joints 7 and 12 are similar and are illustrated in Figure 4. In these joints the pin 30 is fixed in the central member, and the ends rotate in the bushing's 31, preferably of bushing cloth. The joint 5 is illustrated in Figure 5 and is similarly constructed, except that the bushings are preferably of relatively hard material, such as a phenol condensation product impregnated with graphite. In joints 10 and 15, on the. other hand, the pin 33 is fixed, in the outer members and rotates in a bushing 34, preferably of bushing cloth, in the central members, washers 35 of bushing cloth being provided to permit a certain amount of lateral freedom.

The so-called repetition spring serves to balance the weight of the hammer 9 and the driver 6, and in order that the effectiveness of the spring maybe varied in different sections of the piano in which the weight of these parts may differ, means are provided. in the preferred embodiment illustrated, for shifting the point of attachment of one end of the spring. Thus a plurality of spaced holes 36 are provided in the driver 6. In the position illustrated the spring is least effective, but as it is progressively moved to other positions, its effectiveness is increased.

This spring is preferably so adjusted that when the parts are in the position illustrated in Figure 3, if the key is released somewhat so as to free the hammer from the back check 39, the hammer will move slightly upwardly toward the string.

As will be observed,, when the entire action is adjusted in this manner, although the effectiveness of the spring is different in different sections of the action, the pressure of the spring on the keys is uniform throughout the action.

In order to prevent a certain action known as "freezing" which may sometimes occur in case of extraordinarily rapid repetition, or in case of an extremely heavy blow this term being used in cases in which the rear end of the key may return only part of the way to

its normal position and may start upward again before the knuckle joint returns to normal position, or in cases in which the hammer on rebound drives itself deeply into the backcheck the shoulder 40 is provided on the driver 6 to cooperate with the shoulder 41 on the member 11, a pad 42 of felt or other silencing material being located therebetween.

As will be observed, under, the extraordinary conditions described, the shoulders may engage either to cause the knuckle members 11 and 13 to assume normal position, or else said shoulders may engage to prevent the hammer from being driven back sufficiently to cause the backcheck to lock the hammer on the next succeeding stroke of the key.

As previously explained, the normal rest position of the action is illustrated in Figure 1. If now, the forward end of the key (not illustrated) is depressed, the rear end of the key 14 rises toward the key stop rail 37, and the upward motion of. the key is transmitted through the capstan screw 18 and parts 17 and 16 to the knuckle links 13 and 11. Since at this time the pin joint 12 is in front of the line of centers connecting the pin joints 10 and 15, the upward thrust of the key is transmitted directly through the knuckle links to the driver 6, causing the driver to swing about the pin joint 5 so as to carry the hammer 9 in the direction of the string 38.

As the driver 6 swings about the pivot 5; the knuckle breaker screw 27 eventually comes into contact with the pad 28, thus causing the pin joint 12 to be pushed rearwardly of the line of centers connecting the pin joints 10 and 15. Almost immediately thereafter, the driver stop screw 23 comes into contact with the driver stop 22, thus preventing any further swinging motion of the driver 6 in that direction. The acquired momentum of the hammer 9, however, causes it to swing about the pin joint 7 to impart a blow to the string 38, after which the hammer rebounds freely from the string against the silencing material 29 which is secured to the driver 6.

The downward momentum of the hammer acquired on the rebound is now transmitted to the driver 6. causing the said driver to swing in a clockwise direction, but inasmuch as the pin joint 12 is now to the rear of the line of centers connecting the pin joints 10 and 15 as illustrated in Figure 2, such clockwise motion of the driver 6 only results in a further breaking of the knuckle joint as illustrated in Figure 3, and this continues until the rebound of the hammer is stopped by engagement of the hammer with the backcheck 39.

If now the key is released entirely by the operator, the backcheck 39 first swings away from the hammer, permitting the repetition spring 24 to raise the driver and hammer slightly. This in turn permits the spring 24 to thrust the knuckle members 11 and 13 to normal position, after which the weight of the key serves to pull the knuckle links and connected parts to their original positions as illustrated in Figure 1. Preferably the rear ends of the keys are weighted for this purpose.

In some cases, as with very rapid repetition the key is only permitted to return part way toward normal rest position before another blow is imparted. Under such circumstances the knuckle links return to position such that the knuckle joint is in front of the line of centers connecting joints 10 and. 15 as soon as the hammer is even slightly released, and with sufficient rapidity so that the next impulse may be transmitted through the knuckle links in the usual manner.

It will be understood that the invention may be variously modified and embodied within the scope of the subjoined claims.

I claim as my invention:

1. In a grand piano action adapted to be operated by a key, in combination, a driver pivotally mounted upon a fixed member of the piano, a hammer pivotally mounted on said driver, a knuckle link pivotally connected to said driver, a second knuckle link pivotally connected to said first knuckle link and pivotally connected to said key, cooperating shoulders on said knuckle links to limit pivotal movement of said links with respect to each other in one direction, whereby a thrust transmitting connection is provided between said key and said driver, a depending arm forming part of said driver and arranged to contact with said knuckle links to break said thrust transmitting connection during the latter portion of hammer actuating movement thereof, means for limiting the motion of said driver toward said string, and a compression spring connected to said driver and to said second knuckle link.

2. In a grand piano action adapted to be operated by a key in combination, a driver pivotally mounted upon a fixed member of the piano, a hammer pivotally mounted on said driver, a knuckle link pivotally connected to said driver, a second knuckle link pivotally connected to said first knuckle link and pivotally connected to said key, cooperating shoulders on said knuckle links to limit pivotal movement of said links with respect to each other in one direction; whereby a thrust transmitting connection is provided between said key and said driver, a depending arm. forming part of said driver and arranged to contact with said knuckle links to break said thrust transmitting connection during the latter portion of hammer actuating movement thereof.

3. In a piano action adapted to be operated by a key, in combination, a driver pivotally mounted upon a fixed member of the piano, a hammer pivotally mounted on said driver, a pair of knuckle links, pivotally connected to each other and pivotally connected to the driver and key, respectively, and providing a thrust transmitting connection therebetween, and means whereby motion of said driver may move said knuckle links to break said thrust transmitting connection prior to impact of the hammer against the string.

4. In a piano action, adapted to be operated by a key, in combination, a driver pivotally mounted upon a fixed member of the piano, a hammer pivotally mounted on said driver, a pair of knuckle links, pivotally connected to each other and pivotally connected to the driver and key, respectively, and providing a thrust transmitting connection therebetween, means whereby motion of said driver may move said knuckle links to break said thrust transmitting connection prior to impact of the hammer against the string, and means for limiting the motion of said driver toward said string.

5. In a piano action adapted to be operated by a key, in combination, a driver pivotally mounted, upon a fixed member of the piano, a. hammer pivotally mounted on said driver; a pair of knuckle links, pivotally connected to each other and pivotally connected to the driver and key, respectively, and providing a thrust transmitting connection therebetween, means whereby motion of said driver may move said knuckle links to break said thrust transmitting connection prior to impact of the hammer against the string, and a compression spring connected to said driver and to said knuckle links.

6. In a piano action adapted to be operated by a key, in combination, a hammer mounted to swing against a string, a thrust transmitting connection intermediate said key and said hammer, and means actuated by said key for breaking said thrust transmitting connection prior to impact of the hammer against the string.

7. In a piano action adapted to be operated by a key, in combination, a hammer mounted to swing from position of rest to a. position for impact against a string, means providing a thrust transmitting connection between said key and. said hammer, and. means pivotally mounted on a fixed part of the piano and actuated by said key for breaking said thrust transmitting connection prior to impact of the hammer against the string.

8. In a grand piano action adapted to be operated by a key, in combination, a driver movably mounted upon a fixed member of the piano, a hammer movably mounted on said driver, arid. thrust transmitting connections between said driver and key.

9. In a grand piano action adapted to be operated by a key, in combination, a driver movably mounted upon a fixed member of the piano, a hammer movably mounted on said driver, thrust transmitting connections between said driver and key, and means for breaking said connections prior to impact of the hammer against the string.

10. In a grand piano action adapted to be operated by a key, in combination, a driver movably mounted upon a fixed member of the piano, a hammer movably mounted on said driver, and means for limiting the movement of said driver in the direction of the string.

11. In a grand piano action adapted to be operated by a key, in combination, a driver movably mounted upon a fixed member of the piano, a hammer movably mounted on said driver, thrust transmitting connections between said driver and key, and means for limiting the movement of said driver in the direction of the string.

12. In a piano action adapted to be operated by a key, in combination, a driver movably mounted upon a fixed member of the piano, a hammer movably mounted on said driver, and a compression spring having one end bearing against said driver and the other end bearing against said key, said spring being adjusted to balance the weight of the driver and hammer.

13. In a piano action adapted to be operated by a key, in combination, a driver movably mounted upon a fixed member of the piano, a hammer movably mounted on said driver, and means to balance the weight of the driver and hammer.

14. In a piano action adapted to be operated by a key, in combination, a driver movably mounted upon a fixed member of the piano, a hammer movably mounted on said driver, and a compression spring having one end bearing against said driver and the other end bearing against said key, and means whereby the position of the driver end of the spring maybe varied depending upon the weight of the parts of the action.

15. In a piano action adapted to be operated by a, key, in combination, a hammer mounted to swing from a position of rest to a position for impact against a string, means providing a thrust transmitting connection between said key and said hammer, and means actuated by said key to move into contact with said thrust transmitting connection to break said connection prior to impact of the hammer against the string.

16. In a grand piano action adapted to be operated by a key, in combination, a hammer mounted to swing from a position of rest to a position for impact against a string, connections between the key and hammer for actuating the hammer and means for positively limiting the movement of said actuating connections in hammer actuating direction.

17. In a grand piano action adapted to be operated by a key, in combination, a hammer mounted to swing from a position of rest to a position for impact against a string, a driver having connection with said hammer and key, and means for positively limiting the movement of said driver in hammer actuating direction.

18. In a grand piano action, adapted to be operated by a key, in combination, a driver movably mounted upon a fixed member of the piano, a hammer movably mounted on said driver, a pair of knuckle links, pivotally connected to each other and pivotally connected to the driver and key, respectively, and providing a thrust transmitting connection therebetween, means whereby motion of said driver may move said knuckle links to break said thrust transmitting connection prior to impact of the hammer against the string, and resilient means for returning said knuckle links to normal position.

19. In a piano action adapted to be operated by a key, in combination, a hammer mounted to swing from a position of rest to a position for impact against a string, means providing a thrust transmitting connection between said key and said hammer, said connection including a clip detachably secured to the key.

20. In a piano action adapted to be operated by a key, in combination, a hammer mounted to swing from a position of rest to a position for impact against a string, means providing a thrust transmitting connection between said key and said hammer, said connection including a capstan screw and a clip detachably secured to the head of said capstan screw.

21. In a piano action, in combination, a d-river movably mounted upon a fixed member of the piano and means for positively limiting the movement of said driver in hammer actuating direction, said means including a channel member mounted upon affixed member of the piano and a strip of silencing material mounted in said channel member.

22. In a grand piano action adapted to be operated by a key, in combination, a driver pivotally mounted upon a fixed member of the piano, a hammer pivotally mounted on said driver, a knuckle link pivotally connected to said driver, a second knuckle link pivotally connected to said first knuckle link and pivotally connected to said key, cooperating shoulders on said knuckle links to limit pivotal movement of said links with respect to each other in one direction, whereby a thrust transmitting connection is provided between said key and said driver, a depending arm forming part of said driver, and an adjustable screw mounted in said depending arm and arranged to contact with said knuckle links to break said thrust transmitting connection during the latter portion of hammer actuating movement thereof.

23. In a grand piano action, adapted to be operated by a key, in combination, a driver pivotally mounted upon a fixed member of the piano, a hammer pivotally mounted on said driver, a pair of knuckle links, pivotally connected to each other and pivotally connected to the driver and key, respectively, and providing a thrust transmitting connection therebetween, means whereby motion of said driver may move said knuckle links to break said thrust transmitting connection prior to impact of the hammer against the string and means for limiting the motion of said driver toward said string, said means including an adjustable screw carried by said driver.

24. In a piano action adapted to be operated by a key, in combination, a driver movably mounted upon a fixed member of the piano, a hammer movably mounted on said driver, and means for limiting the movement of said driver in the direction of the string, said means including an adjustable screw carried by said driver.

25. In a piano action adapted to be operated by a key, in combination, a driver movably mounted upon a fixed member of the piano, a hammer movably mounted on said driver, thrust transmitting connections between said driver and key, means for breaking said connections prior to impact of the hammer against the string, and resilient means for returning said thrust transmitting connections to normal position.

26. In a piano action adapted to be operated by a key, in combination, a driver movably mounted upon a fixed member of the piano, a hammer movably mounted on said driver, thrust transmitting connections between said driver and key, and means for breaking said connections prior to impact of the hammer against the string, said means including an adjustable screw carried by said driver.

27. In a piano action adapted to be operated by a key, in combination, a driver movably mounted upon a fixed member of the piano, a hammer movably mounted on said driver, a pair of knuckle links pivotally connected to each other and pivotally connected to said driver and key, respectively, and providing a thrust transmitting connection therebetween, and means including cooperating abutting faces on said driver and one of said knuckle links for preventing freezing.

28. In a piano action adapted to be operated by a key, in combination, a hammer, driving connections between said key and hammer, a backcheck, and means to retard the rebound of the hammer and restore the driving connections to original positions.

29. In a piano action adapted to be operated by a key, in combination, a hammer, driving connections between said key and hammer, including a knuckle link, a backcheck, and means for transmitting the rebound thrust of said hammer to said knuckle links subsequent to engagement of said hammer by said backcheck.

30. In a piano action adapted to be operated by a key, in combination, a hammer, driving connections between said key and hammer, a backcheck, and means for transmitting the rebound thrust of said hammer to said driving connections subsequent to engagement of said hammer by said backcheck.

31. A piano action comprising in combination, a key, a hammer, driving means between said key and hammer, and means set into motion by said key for arresting the action of said driving means upon said hammer.

32. A piano action comprising in combination, a key, a hammer, driving means between said key and hammer, and means set into motion by said key and having an amplitude of movement greater than that of the key for arresting the action of said driving means upon said hammer.

33. A piano action comprising in combination, a key, a hammer, knuckle links for projecting said hammer by movement of said key, and moving means for breaking the joint of said knuckle links.

34. A piano action comprising in combination, a key, a hammer, knuckle links for projecting said hammer by movement of said key, and means movable transversely of said links for breaking the joint therebetween.

35. A piano action comprising in combination, a key, a hammer, knuckle links for projecting said hammer by movement of said key, and means including an L-shaped member for breaking the joint of said knuckle links when moving in one direction and for restoring said links to operative condition in another direction.

36. A piano action comprising in combination; a key, a hammer, a direct breakable driving connection between said key and hammer, and a spring connected across the breakable joint of said driving connection.

37. A piano action comprising in combination, a key, a hammer, a direct breakable driving connection between said key and hammer, and means moving bodily with said driving connection and acting to support said hammer when the driving action of said connection has been discontinued.

38. A piano action comprising in combination, a key, a hammer, a direct breakable driving connection between said key and hammer, and a free floating resilient connection acting upon said hammer upon its rebound stroke almost immediately after it leaves the piano string.

39. In a piano action in combination, a key, a hammer, driving links between said key and hammer and an intermediate member pivotally connected to said hammer and links and provided with abutment surfaces adapted to cooperate with said hammer and links respectively.

40. In a piano action in combination, a key, a hammer, driving links between said key and hammer and an intermediate member pivotally connected to said hammer and links and provided with a free end disposed between said hammer and links and having abutment surfaces for each.

41. In a piano action, in combination, a key, a hammer, driving connections between said key and hammer including a driver movably mounted on a fixed member of the piano, and thrust transmitting connections between said driver and key, said hammer being mounted to swing on said member, and said thrust transmitting connections being connected to said driver at a point between its connection to said fixed member and its connection to said hammer.

In testimony whereof, I have signed my name to this specification this 20th day of July, 1928.

CLARENCE N. HICKMAN