Abstract: An annular drilling hammer having an annular bore crown guided between an outer tube and an inner tube. An annular hammer piston periodically strikes the bore crown and has a piston member that is guided in a cylindrical chamber having control apertures which are connected fluidically to a reversing valve. The working medium is delivered to the reversing valve between an inner tube system and an outer tube system. After driving the hammer piston the medium is discharged from the drill between the outer tube and the bore crown. The bore crown is provided with flow channels leading from the rear shoulder through and to the front and/or central aperture of the bore crown. The flow of driving medium through these channels aids the entrainment of bored material, which then is carried out through the inner tube with the aid of a Venturi opening.

Abstract: This drilling device includes a hydraulic motor, coaxially surrounding the drill rod, for rotating the drill. The rotor of the motor directly rotates the drill, without the use of gears. Advantageously, the rotor includes a replaceable adapter sleeve that has a shape conforming to the peripheral shape of the drill. By replacing the sleeve, drill rods of different shape or size can be accommodated. The rotor may be of the wing cell type, wherein a plurality of radially moveable vanes or wings project radially from a circular rotor into contact with the inner wall of a non-circular cylinder wall. The vanes define cells within which the hydraulic fluid presses against the vanes so as to impart rotation to the rotor, sleeve and drill.

Abstract: This disclosure relates to a percussion tool which includes a housing having a chamber reciprocally mounting a piston with first and second pressure ducts at opposite ends of the latter and a control duct therebetween as well as a return duct in fluid communication with the chamber at a point intermediate the points of entry of the first and second pressure ducts and reciprocal valve means for controlling the reciprocal motion of the piston, the improvement including a plurality of branch ducts of the control duct opening into the chamber in such a fashion that the branch ducts are successively opened and closed during the reciprocation of the piston.