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 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.