| 摘要 |
The subject action is a modification of the traditional upright action. The traditional jack spring is eliminated. Its function is assumed by a jack/repetition spring, which is a compression spring adjustably mounted between the jack near the end that engages the hammer butt and a pilot attached to the back stop portion of the hammer assembly. The hammer return spring mounting enables adjustment of the range of force applied by the spring to the hammer. The force range magnitude is such that the hammer return torque is commensurate to the torque that would be applied by gravity if the hammer shank were mounted horizontally instead of vertically. The operating force of the jack/repetition spring is related to that of the hammer return spring in such a way that re-engagement of the jack with the hammer butt is assured before hammer return beyond the back-checked point. The ends of the jack/repetition spring are geometrically located to allow the elements of the action to keep in intimate contact after re-engagement, making possible the elimination of the bridle tape and wire, and to provide a function that feels smooth and tight, not loose. The interaction between the springs as applied produces enough return force on the key to allow use of weights in the played end of the key to provide the desirable inertial resistance of a grand action to the player's touch on the keys. With the subject action properly adjusted, the hammer assembly rests upon the jack, rather than the traditional rest rail and therefore there is space between the hammer shank and hammer rest rail when the action is at rest.
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