| 摘要 |
The hammer drill (1) comprises a body (2) containing an alternating impact piston (4) which slides under the effect of a main hydraulic supply circuit (22). The circuit also causes an annular stop piston (5) to slide in a body cavity (3). The stop piston comprises a front face, in contact with an insert (7), which positions the insert at a pre-determined distance from the impact piston. When the main circuit is stopped, an external hydraulic supply circuit (23) can introduce pressurized fluid between the stop piston rear face and the cavity rear wall so as to maintain a space between them. |
