Abstract: A method of crushing material between cooperating jaws of a crushing jaw assembly of a demolition tool includes the steps of applying a closing force to at least one of the jaws for urging the jaws toward one another; and imparting a vibratory motion to at least one of the jaws while the closing force is applied.

Abstract: A drilling apparatus includes a drill rod unit having at least one drill rod; a percussion mechanism having a housing; a percussion piston having an axis and being slidably received in the housing; and a hydraulic system for generating pressures in the housing for effecting an axial reciprocation of the percussion piston in the housing for delivering blows to the drill rod unit in a direction parallel to a direction of reciprocation. The housing has opposite, axially aligned open ends and the percussion piston has a throughgoing axial passage in alignment with the open ends of the housing. The drill rod unit extends into the axial passage and has a counterface situated in a path of travel of the percussion piston for being impacted by an end thereof. The percussion mechanism is receivable on the drill rod unit at either selected side of the counterface for delivering blows to the drill rod unit in a selected one of two opposite directions.

Abstract: A demolition tool includes a carrier body and two tool blades mounted thereon to define a tool mouth for receiving material to be crushed. The demolition tool further has a hydraulic cylinder including a cylinder housing as well as first and second chambers defined therein. A piston rod is received in the cylinder housing and projects therefrom for moving at least one of the blades. First and second pistons are spacedly affixed to the piston rod and bound the first and second chambers, respectively. Hydraulic fluid is introducible into the first and second chambers for exposing the pistons to pressure to generate a force for moving the piston rod in a working direction. A control unit is operatively connected to the chambers for controlling admission of hydraulic fluid thereto. The control unit has a first position in which the control unit admits hydraulic fluid solely to the second chamber and a second position in which the control unit admits hydraulic fluid under pressure to the first chamber.

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: A hydraulically operated striking mechanism includes a contact pressure control member held at least temporarily in contact with an insertion end of a drilling tool by a mechanism which applies a restoring force in the striking direction. A control conduit is connected by way of the contact pressure control member either to a pressure conduit or to a pressure return conduit. The control conduit actuates a switching element so that a control unit which alternatingly switches the movement of the striking piston performs a reversal movement into an operating stroke position at an earlier or later point in time during the return stroke of the striking piston and thus actuates the operating stroke of the striking piston in the striking direction.

Abstract: A hydraulically operated hammer drill includes a housing in which a striking piston is displaceably disposed for alternating movement. The striking piston is driven in striking and return directions by a first operating pressure. A rotatable, tool receiving device is connected to the housing for receiving an insertion end of a drilling tool and permitting displacement of the insertion end in the longitudinal direction when charged by the striking piston. A rotation drive mechanism, driven by a second operating pressure, is mounted for rotatably driving the tool receiving device during longitudinal displacement of the insertion end. A control unit is disposed along a pressure conduit supplying the first operating pressure for alternatingly switching the direction of movement of the striking piston by controlling application of the driving medium to control faces of the striking piston.

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.