Abstract: A control system for a hydraulic percussion mechanism (6) is based on the continuous measurement of the striking rate (z) of the striking piston, or on the continuous measurement of the striking rate (z) of the striking piston together with the quantity per unit time (Q.sub.e) of the hydraulic driving medium coming into the percussion mechanism (6). One, or possibly both, of these parameters is measured from outside the percussion mechanism itself. The control system is configured in such a way that the internal resistance of the percussion mechanism or the hydraulic pump which powers it is increased if there is an increase in the striking rate (z) or the ratio z/Q of the striking rate to the incoming stream rate beyond respective limit values.

Abstract: A measuring device connectable to a pressure conduit of a hydraulic circuit for determining characteristic operational parameters of hydraulic energy converters forming components of the hydraulic circuit includes a measuring section having a conduit guiding pressurized fluid of the pressure conduit and a throttle in the conduit for effecting a pressure drop thereacross; a differential pressure transducer communicating with the conduit at an upstream side and a downstream side of the throttle as viewed in a direction of fluid flow for determining a pressure differential across the throttle and for generating an output signal representing the pressure differential; and an electrotransducer connected to an output of the differential pressure transducer for separating the output signal into an alternating voltage component signal and a direct voltage component signal. The electrotransducer has an output to which the alternating voltage component signal and the direct voltage component signal are applied.

Abstract: An automatic lubricating arrangement for a chisel of a hydraulic striking mechanism. A conveying unit is adapted for connection to the chisel guide supporting the chisel of the striking mechanism for charging the chisel guide with lubricating grease and is further connected to the source of operating pressure for the striking mechanism. The conveying unit includes a conveying chamber for receiving lubricating grease and a mechanism for performing a predetermined conveying stroke of adjustable magnitude each time the striking mechanism is charged with operating pressure for forcing lubricating grease out of the chamber and into the chisel guide under pressure derived from the source of operating pressure. A lubricant reservoir for storing lubricating grease is connected to the conveying unit and has a movable separating element and compression spring biasing the separating element against the lubricating grease for supplying lubricating grease to the conveying chamber of the conveying unit.