Abstract: A hammer drill comprises a housing with a cylinder in the housing defining a cylindrical piston chamber and an air chamber located around at least a portion of the piston chamber sealed against the ambient atmosphere and against adjacent components of the housing. The housing defines a tool-receiving chamber aligned with and communicating with the piston chamber and a percussion body is movable in a piston chamber against a tool positioned in the tool-receiving chamber. The piston is reciprocated through a crank drive by an electric motor within the housing toward and away from a percussion body. The cylinder defines a pneumatic buffer zone between the piston and the percussion body so that air which is displaced by the movement of the piston provides a coupling and buffing fluid between the piston and the percussion body.

Abstract: A hammer tool such as a rotary hammer, hammer drill or the like includes a motor housing and a gear case secured to the motor housing forwardly of the motor housing. A motor in the motor housing has a shaft projecting into the gear case and a pinion formed on the end of the motor shaft. A first set of ratcheting teeth is formed on a body rotatably journaled in the gear case. An output spindle for holding a tool bit is provided and has a longitudinal axis. The output spindle is rotatably journalled in the gear case so as to be also slideable in the direction of said longitudinal axis. A second set of ratcheting teeth is mounted on the output spindle so as to be in confronting relation to the first set of ratcheting teeth. A spring provides a resilient force for holding the first and second sets of ratcheting teeth in spaced apart relation to each other.

Abstract: A force-transmitting arrangement for use in hammer drills and the like includes an internal thread in a chuck of a power tool and an external thread on a portion of the tool element which is to be mounted in the chuck, both threads being of compatible, basically trapezoidal, configurations. The flat flanks of the trapezoidal internal and external threads are offset in the radially outward direction with respect to the mean effective thread diameter. The external thread is rounded at its root with a radius substantially corresponding to the thread height of the external thread, and the internal thread is similarly rounded at its crest with a radius substantially corresponding to the thread height of the external thread, and/or chamfered.

Abstract: An improvement to a conventional slap-hammer which allows the hammer to be rotated by a pneumatic wrench or like device. A universal joint is attached to the top of the slap hammer to enable the latter to be rotated by the output shaft of a pneumatic wrench. The housing of the wrench is held by a closable harness that encircles the housing when closed and thereby prevents the output shaft from becoming disengaged from the universal joint.

Abstract: A drill for use especially with percussion drilling machines and rotary drill hammers for working rock and concrete is disclosed. The drill includes an elongated shank having a leading and trailing end, the latter of which is adapted to receive axial blows from the drilling machine. A unitary plastic receiving part at least partly encloses and mechanically interlocks with the shank periphery adjacent the trailing end of the shank. The exterior of the plastic receiving art is threaded for engagement with interior threads of a drilling machineadapter.

Abstract: A torque-transmitting system, particularly a hammer drill, has a housing provided with a tool holder section, and a driven output shaft which is journalled in the housing and has a free end portion at the tool holder section. A tool has a shaft provided with an end portion of profiled cross-section, the profiling of the cross-section being inclined circumferentially of the end portion. A receiver for the end portion is formed in the tool holder and configurated for matingly receiving the profiled end portion, so that the tool is held in the tool holder section in motion-transmitting relationship with the free end portion of the shaft.

Abstract: A drilling machine may include extension equipment comprising (a) drill rods -- connected end-to-end -- for transmission of impact force and (b) a system of tubular members -- likewise connected end-to-end -- surrounding said rods, for transmission of rotary force. Such extension equipment may be coupled to the machine per se by means of a tubular adapter threadably connected, at one of its ends, to the tubular members system and at its opposite end connected to the machine through polygonal coupling means.