Black Decker Inc.

Robert Bernhard Wache

Manfred Droste

Ernst Staas

Heinz-Werner Faatz

Bruno Meinholf Ruethers

Thomas Michael Stanke

Reinhard Plietsch

A method of assembling a hand held electrically powered drilling and/or hammering tool having a tool housing and a drilling and/or hammering spindle mounted within the housing. The spindle has a forward end at which a tool or bit may be mounted. The method of assembly includes the steps of making a motor sub-assembly including a motor and a radial fan, the fan has a plurality of blades located on one side of the fan and non-rotatably mounting the fan on an end of the armature shaft of the motor at a first end of the motor with the blades facing away from the armature of the motor. The method further including balancing the motor sub-assembly, and mounting the sub-assembly within the housing, with the longitudinal axis of the motor armature shaft at an angle, preferably perpendicular to the longitudinal axis of the spindle and with the first end of the motor closest to the spindle axis. Thus, in use of the tool, the fan rotates at the first end of the motor to draw air into its inlet via air inlets in the housing and so as to push air through the motor and out of air outlets in the housing in the region of the second end of the motor which is remote from the spindle axis. A drilling and/or hammering tool made according to the method is also described.

Method of assembling a drilling and/or hammering tool

A tool holder attachable to a spindle of a hammer and which can receive a bit, the bit having a shank with at least one retaining groove extending along part of the shank, the retaining groove having a defined length, a front end and a rear end that limit axial movement of the bit in the tool holder, which tool holder comprises a hollow cylinder having an axis, an axial bore, a rear end that can be attached to the spindle of the hammer, and a front end that can receive the shank of the bit so that the bit is slidable within the cylinder in an axial direction, at least one retaining element that is located so that it can extend radially into the bore of the cylinder and into the at least one retaining groove of the bit so that the retaining element can be hit by the rear end of the retaining groove during the transition to idling and limit the extent of axial movement of the bit within the cylinder, at least one radial restraining element limiting movement of the retaining element in the radial direction, at least one axial restraining block limiting movement of the retaining element in the axial direction, when hit by the retaining element the axial restraining block movable to a limited extent in the axial direction with respect to the radial restraining element, and a resilient element located forward of the axial restraining block and arranged so as to attenuate the impact transmitted through the axial restraining block from the retaining element.

Rotary hammer

A rotary hammer is provided which comprises a tool holder (,) and an air cushion hammering mechanism which comprises a cylinder (,&prime;) having one end (,) that is connected to the tool holder, a piston (,), a ram (,) and a beat piece (,) slidably located in the cylinder so that reciprocation of the piston in the cylinder will cause the ram to reciprocate in the cylinder and thus cause the beat piece to hit a bit located in the tool holder. The ram (,) has an annular recess (,) in its peripheral surface at the end thereof nearest the piston (,), in which recess is located an annular seal (,). The annular seal has an annular seating flap (,) lying on the radially outwardly directed surface of the recess and an annular sealing flap (,) that is joined to the seating flap and extends between the radially outwardly directed surface of the recess and the inner wall of the cylinder (,&prime;).

A rotary hammer has a pneumatic hammering mechanism driven by a wobble plate drive arrangement. A rotatably driven intermediate shaft transmits torque for rotating a tool holder. A carrier sleeve is rotatably mounted on the intermediate shaft and is elastically coupled with the intermediate shaft for limited rotational displacement relative thereto. The tool holder is rotatably driven via gearing by the carrier sleeve. On a suitable portion of the carrier sleeve a hub body of the wobble plate drive is mounted so as to be rotatable relative to the carrier sleeve but non-rotatable in relation to the intermediate shaft. In use, when a hammer bit in the tool holder is placed under load, the carrier sleeve and the intermediate shaft are caused to rotationally displace relative to each other as a result of the elastic coupling, wherein the inclination of the hub body of the wobble plate drive alters and with this the hammering stroke is altered.

Rotary hammer with variable hammering stroke

A rotary hammer has a pneumatic hammer mechanism which can be driven by means of a driver-part mounted rotatably on an intermediate shaft, with which driver-part a first coupling element of a coupling is non-rotatably connected, while the second coupling element of the coupling is non-rotatably mounted on the intermediate shaft and through axial displacement can be brought into positive coupling engagement with the first coupling element. A synchronizing arrangement is provided, which on approach of the coupling elements to one another, accelerates the first coupling element at least approximately to the rotational speed of the second coupling element and only then permits the positive engagement of the coupling elements.

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Wiesbaden, Germany

Robert Bernhard Wache