| 摘要 |
In a cylinder formed in a casing a hammer piston is mounted for reciprocating motion and is subjected to periodic pressure pulses from a pressure fluid. To prevent a reaction emanating from each pressure pulse from also acting as a shock on the casing, a balance or compensation mass body is provided in the casing which mass body is subjected to the pressure pulses in the direction opposite to that for the hammer piston and is displaceable parallel to the latter against the action of a spring supported in the casing. Together with the spring, the mass body forms an oscillator, the characteristic frequency of which is advantageously to be selected to be at most half, but preferably one third, of the frequency of the pressure pulses. In this way, the reaction shocks are smoothed out to a recoil force which fluctuates narrowly about a mean value and which can be kept lower than the weight of the casing, so that the casing is not subjected to any recoil accelerations. |
