Power tool

Claim 1

A power tool, particularly a hand-held pneumatically driven power screwdriver or other hand-held power tool, comprising, in combination, a tool housing, a drive motor in the housing, a spring-loaded release valve device arranged in an energy supply conduit leading to the motor for blocking and unblocking the energy supply conduit, a tool holder rotatably mounted at the front of the housing, a clutch including a hollow driving part connected to the motor and a driven part connected to the tool holder, the clutch being axially shiftable together with the tool holder, the driven part having a plurality of clutch depressions bounded by sloping clutch ridges, the clutch including clutch elements located in the clutch depressions, the clutch including an axially shiftable pressure body surrounding the driving part, adjustable-stress first spring means causing the pressure body to urge the clutch elements to the bottoms of the clutch depressions, the driving and driven parts being immovable relative to each other in axial direction, the driving and driven parts becoming rotatable relative to each other when the torque transmitted by the clutch reaches a predetermined value causing the clutch elements to climb up the associated sloping clutch riges and out of the clutch depressions, the clutch further including a locking bolt guided in the interior of the driving part for axial movement relative to the driving part and being coupled to transmit force to the release valve when axially moved, the locking bolt being guided in the driving part non-rotatable relative to the latter and having at least one radial bore, the driving part having at least one radial bore which can be brought into register with the radial bore of the locking bolt, the clutch further including at least one outer and one inner radially shiftable locking element in the radial bores the inner one of which serves when the bores are in register for locking the driving part and the locking bolt together for joint axial movement so that axial movement of the clutch in response to axial movement of the tool holder causes the locking bolt to transmit force from the driving part to the spring loaded release valve device, the pressure body having a cam surface which faces towards the driving part, the clutch further including second spring means operative for causing the inner locking element to urge the outer locking element radially outward into abutment against the cam surface, the cam surface being so configurated that when the clutch elements climb out of the clutch recesses and push back the pressure body against the opposition of the first spring means the cam surface of the pressure body drives the locking elements radially inward to a position in which the locking elements no longer lock the driving part and locking bolt together for joint axial movement, whereby the locking bolt can no longer transmit axial force from the clutch to the release valve.