Abstract: A double-acting hydraulic jack has a cylinder, a piston dividing the cylinder into first and second chambers of variable volume on opposite sides of the piston, and a piston rod with first and second passages opening into the first and second chambers respectively. The piston is moved by supply of pressurized fluid to one passage or the other. An end-of-stroke device is provided to relieve the high pressure applied to the first chamber when the piston comes to the end of its stroke under the action of the pressure fluid supplied to that chamber through the first passage. The device comprises a bore in the piston. The axis of the bore is parallel to the piston axis. The bore contains a small moveable rod urged to project from the bore into the second chamber by high fluid pressure taken from the first passage to move a sliding sleeve in the bore. This sleeve movement is transmitted to urge the small rod and also blocks a third passage leading to the bore from the first passage.

Abstract: A combined device for reaming and collecting dust for use with a drilling apparatus makes it possible to produce a flared mouth for the drilled hole, in particular for subsequently facilitating the insertion of an anchor bolt. The device includes a reamer, through which the drilling bit of the apparatus passes axially, and which is integral with a sleeve through which the bit also axially passes and which is coupled to a hydraulic speed-reducing motor. The inner diameters of the sleeve and of the reamer are greater than the diameter of the bit, in order to provide an annular passage for the evacuation of dust. A container for collecting dust and provided with a guide for the drilling bit is disposed on the side of the driving sleeve opposite the reamer.