Abstract: A hollow crown drill has a set of cutting members (2, 3, 4) positioned on the leading or cutting end of an annular axially extending carrier member (1). The radial width of the cutting faces (2a, 3a, 4a) of the cutting members (2, 3, 4) increases opposite to the rotational direction (D) of the carrier member (1). In addition, the cutting members (3, 4) in the set disposed counter to the rotational direction (D) are offset in the direction parallel to the axis of the carrier member relative to the cutting member of the set leading in the rotational direction. This dimensional feature relates to the increase in the size of the cutting faces (2a, 3a, 4a). With the cutting faces (2a, 3a, 4a) dimensioned as above, each of the cutting members penetrates deep into the material being drilled, so that if the usual contact pressure forces are applied abrasive wear resulting in premature failure of the hollow crown drill does not occur.

Abstract: A hollow drilling tool is made up of an axially extending tubular carrier part, a cutting body at one end of the carrier part, and guide elements located in the axial direction of the carrier part between the cutting body and the carrier part. The radially outer surface of each guide element is in alignment in the axial direction of the carrier part with the radially outer surface of the cutting body. The guide elements guide the hollow drilling tool in a borehole formed by the cutting body.

Abstract: A manually guided motorized hand tool used for drilling and/or percussive drilling includes a housing with a mass movably mounted about the drilling axis for movement relative to the housing. A switch is mounted on the housing and is operable by the mass when it moves a certain angular distance relative to the housing. When operated, the switch cuts off the power supply to the hand tool.

Abstract: Fastening elements, such as bolts, studs or nails, are inserted into a hard receiving material, such as concrete or rock, first, by drilling a blind borehole into the receiving material. The diameter of the borehole is formed so that it is greater than the diameter of the leading end of the fastening element. A setting device containing the fastening element is then aligned with the blind borehole and the fastening element is driven into the receiving material. The fastening element enters the receiving material at the base of the blind borehole. The length of the fastening element inserted into the receiving material is at least half the axial length of the borehole and may have a length considerably greater than the axial length of the borehole.