| 摘要 |
Apparatus comprising a striking piston driven hydraulically in a reciprocating fashion by an incompressible fluid inside a cylinder and striking against a tool, of the type in which the piston slides in a cylinder having two concentric piston bearing surfaces of different sections, of which that situated on the tool side has a section smaller than that remote from the tool, the piston and the cylinder delimiting two antagonistic chambers, an annular bottom chamber and a top chamber of larger section. According to the invention the interior of the top chamber is permanently at a regulated pressure of a value intermediate between the inlet or high pressure and the outlet or low pressure, and the annular bottom chamber is connected alternately by a distributor to the high pressure supply circuit during the upward phase of the piston and to the top chamber during the accelerated downward phase of the piston.
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