| 摘要 |
942,668. Percussive tools. ROBERT BOSCH G.m.b.H. May 2, 1960 [April 30, 1959], No. 15283/60. Heading B4C. A motor-driven percussive tool comprises a casing, a hollow cylinder closed at one end slidable in the casing, a piston slidable in the cylinder, the cylinder or the piston being formed as an impact body the other being connected to a motor by a crank and connecting rod, an intermediate space between the front of the piston and the closed end of the cylinder acting as an air cushion by which the movement of the driven part is transmitted to the impact body, and a valve between the air cushion and the atmosphere which is closed when excess pressure is present in the intermediate space and opened when there is a partial vacuum in the space. |
