| 摘要 |
PROBLEM TO BE SOLVED: To decrease sounds generated subsequent upon a collision to an elastic body by arranging a reversal-urging means of a shuttle mechanism having the elastic body at a nearly middle position between collision faces at a hammer bank side and a counter balancer side. SOLUTION: An elastic body 40 as a reversal-urging means is arranged at nearly a center of a direct acting bearing 12b at the side of a hammer bank 10 on a guide shaft 11 and a direct acting bearing 12c at the side of a counter balancer 21, and moreover nearly a center of the elastic body 40 is fixed by a guide 41. When the hammer bank 10 moves to a left reversal position, the direct acting bearing 12b at the side of the hammer bank collides from the right side of the elastic body 40 at a relative speed (v), and the direct acting bearing 12c at the side of the counter balancer collides from the left side of the elastic body 40 at the relative velocity (v). Supposing that the elastic body 40 is a system reference and a mass of each side is (m), when an energy at the time of the collision at the side of the hammer bank, at the side of the counter balancer is Esh, Esc, a total energy at the collision becomes E1=Esh+ Esc=1/2mv2+1/2mv2=mv2 and dispersed to a heat, a sound, a force pressing the elastic body, and the like.
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