| 摘要 |
<p>This device for an upright piano has a second escapement jack (14). This jack is fixed to the check (9). It can swing about a pivot (16). At one end (15) it extends towards the hammer shank (3) and in the other direction has an end (21). A trigger stop (22), in the form of a button, is fixed to a bar (23) above the second jack. After the first jack (2) has thrown the hammer towards the string (4), it leaves its point of support beneath the butt, through the action of the set-off button (8) on the escapement lever (7). If after striking the string the hammer falls back faster than the key (1) rises, the first jack does not move back under the butt (11). The shank of the hammer then falls onto the end (15) of the second jack. It is then possible, even if the key is allowed to rise only very slightly, to throw the hammer back again by means of the second jack, even if the first jack has not moved back under the butt. At its end of travel, the end (21) of the second jack, which rises with the check, meets the stop (22), and the end (15) rises sharply and lets the hammer reach the end of its travel under its own momentum. A spring (24) restores the second jack to position as soon as pressure on the key is relaxed. <IMAGE></p> |
