Abstract: Apparatus having a pair of presser cheeks for insertion in a drill hole, with a slider wedge slidably engaged therebetween. The forced descent of the slider wedge by a hydraulic cylinder assembly results in the lateral motion of the presser cheeks away from each other. The presser cheeks are supported from the cylinder body of the cylinder assembly, each via two pairs of parallel spaced leaf springs disposed on opposite sides of the slider wedge and normally closely held against the other two pairs of leaf springs supporting the other presser cheek. While the bottom ends of the leaf spring pairs are rigidly coupled to the presser cheeks, their upper ends are connected to the cylinder body via elastic members yieldable to permit upward displacement of the leaf springs with the presser cheeks, as upon withdrawal of the slider wedge, without buckling. Further two pairs of stop rods depend from the cylinder body so as to normally terminate short of the respective presser cheeks.

Abstract: Dust-proof membranes are provided across both ends of opposite respective divided surfaces defined by halves of wedge guide members. Each membrane has projections formed as an integral unit along the longitudinal side edges thereof. The projections are thrust into longitudinally extending C-shape cross-section grooves formed along the divided surfaces of the wedge guide members. The groove side surfaces are perpendicular to the bottom surface thereof.

Abstract: For splitting rock, concrete structures, etc., by being inserted into a drill hole created therein, a rock splitter has a wedge coupled at its thick end to the output shaft of a hydraulic cylinder. Lying on opposite sides of the wedge, a pair of guides are yieldably held against the wedge to allow longitudinal sliding motion thereof. Two pairs of opposed leaf springs connect the wedge guides to the hydraulic cylinder to restrain the guides from longitudinal displacement and to allow same to move away from and toward each other with the longitudinal sliding motion of the wedge. The pair of wedge guides, together with the wedge therebetween, generally taper as they extend away from the hydraulic cylinder for the ease of insertion into the drill hole. Several splitting operations, each with a thrust of the wedge, are to be performed in succession, by inserting the splitter progressively deeper into the drill hole, for fracturing thick rock formations or the like.