| 摘要 |
Hydraulic rotary percussive hammer drill The present invention relates to a hydraulic rotary percussive hammer drill (1) comprising a body (2) containing a reciprocating percussion piston (4) sliding under the effect of a main hydraulic supply circuit (22), this main circuit also being intended to cause the sliding of a roughly annular abutment piston (5) housed in a cavity (3) of the body, and having, on the one hand, a front face in contact with a shank (7) and intended to place this shank a predetermined distance away from the percussion piston and, on the other hand, a rear face facing a rear wall of the cavity, characterized in that an external hydraulic supply circuit (23) is able, when the main circuit is shut down, to introduce fluid under pressure between the rear face of the abutment piston and the rear wall of the cavity so as to maintain a space between these items.
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