Abstract: A hand-held power tool, e.g. a high speed file or polisher has a single rotary drive shaft (8) to which there is locked a first eccentric member (1) in which a second eccentric member (2) can be rotated and locked forming a first assembly (10). The second eccentric member has an eccentrically placed crank pin in the form of a hollow needle bearing ring (2a) through which the drive shaft passes. The outer ring (7) of the needle bearing reciprocally drives a connecting rod (1.2) to a tool holder (9). The drive shaft also passes through an identical assembly (10f) of first and second eccentric members (1?, 2?) disposed upside down on the first assembly (10) and reciprocally driving, in the opposite direction and in counterphase, a counterweight, to cancel the reactive oscillating forces from the tool holder during operation, which would otherwise have to be absorbed by the hand and aim of the operator.

Abstract: A hand-held power tool, e.g. a high speed file or polisher has a single rotary drive shaft (8) to which there is locked a first eccentric member (1) in which a second eccentric member (2) can be rotated and locked forming a first assembly (10). The second eccentric member has an eccentrically placed crank pin in the form of a hollow needle bearing ring (2a) through which the drive shaft passes. The outer ring (7) of the needle bearing reciprocally drives a connecting rod (1.2) to a tool holder (9). The drive shaft also passes through an identical assembly (10f) of first and second eccentric members (1?, 2?) disposed upside down on the first assembly (10) and reciprocally driving, in the opposite direction and in counterphase, a counterweight, to cancel the reactive oscillating forces from the tool holder during operation, which would otherwise have to be absorbed by the hand and aim of the operator.

Abstract: Hand tool with an apparatus housing (2) in which the are movably mounted a rotary portion (8) and a reciprocating slide (10) non-rotatably but displaceably mounted in the housing, said slide serving as a holder for a tool (12). The rotary portion (8) has an oblique shaft (32) with a rolling bearing device (36) mounted thereon, which converts the rotation of the rotary portion into a reciprocating movement of the displaceable portion (10). The rolling bearing device (36) comprises one or two rolling bearings with outer ring surface areas, via which the bearing device is in direct driving contact with a driver element (52) at the end of the displaceably mounted slide (10). The driver element (52) is in direct engagement with the outer rings (48, 50) of the bearing device via opposite lateral surfaces (54, 56).

Abstract: A dental implement designed to be retained for reciprocating-movement by the sleeve member of a dental handpiece. The dental implement is comprised of a flat dental tool having a flat blade portion and a flat shank portion. The flat blade portion can also be formed with a triangular or arcuate cross-section while retaining the flat shank portion and the blade edges can be straight or have a saw-tooth configuration. A removable tool holder has a slot to receive the dental tool and a outside cylindrical shape complementary with the bore of the sleeve member. Forces applied to the tool holder control the displacement of locking protrusions on the tool shank to selectively permit the tool to be driven in a reciprocating movement with or without rotation and to be removed entirely from the sleeve member.