| 摘要 |
PROBLEM TO BE SOLVED: To contribute to improvement of successive depression by making return motion, of a jack to a bottom of a point to be driven of a hammer body, quick at the time of key release.SOLUTION: A contact section 31a of a projection engage section 31 of a jack 30 is a flat slope facing forward and downward, and a receiving section 33a of a stopper felt is a flat slope facing backward and upward. Both of the contact section 31a and the receiving section 33a are positioned at a back side and formed so that they get closer to a position of a tip section 30a of the jack 30 at an initial position, as they are closer to a jack rotation shaft Fj. A rotation position of the jack 30 to a wippen 20 in a relative progressing direction is defined, after the contact section 31a contacts the receiving section 33a. A front side marginal position of the tip section 30a in a front-back direction, which is regulated after the contact section 31a contacts the receiving section 33a, is closer to the position of the tip section 30a at the initial position, as the tip section 30a is positioned at a lower position. |
