초록 ▼

A hammer drill is provided with a clutch whose movable part is firmly connected to an axially displaceable drum which supports a wobbling disc driving a percussive mechanism for striking a work tool. The axially fixed clutch part is rotated by driving motor and is backed-up by a housing of the drill

A hammer drill is provided with a clutch whose movable part is firmly connected to an axially displaceable drum which supports a wobbling disc driving a percussive mechanism for striking a work tool. The axially fixed clutch part is rotated by driving motor and is backed-up by a housing of the drill. Retroacting forces from the percussive mechanism are transferred via the drum onto the movable clutch part so that the engagement of the clutch is reinforced at the moment when the compression generated by percussive mechanism is maximum. When pressure applied on work tool is relieved, a separating spring disengages the clutch and braking surfaces on the drum limit its axial displacement and brake the rotation of the wobbling disc.

대표청구항 ▼

A hammer drill having a housing and, within the housing, means for guiding work tool, a driving motor coupled by a gear train and a motion converting wobble disc means to a percussive mechanism acting via a resilient buffer on an axially reciprocating striking member whose energy is transferred to a

A hammer drill having a housing and, within the housing, means for guiding work tool, a driving motor coupled by a gear train and a motion converting wobble disc means to a percussive mechanism acting via a resilient buffer on an axially reciprocating striking member whose energy is transferred to a work tool inserted in said guiding means, comprising a clutch arranged in said gear train to transmit torque from said driving motor to said wobble disc means when brought in engaged condition in response to a contact pressure of the work tool against a workpiece, the clutch including an axially movable clutch part arranged for joint rotation with the wobble disc means and an axially fixed clutch part driven by said gear train and being backed up by said housing, said means for guiding a work tool being supported for axial movement relative to said housing; and said axially movable clutch part being brought into engagement with said axially fixed clutch part by the action of said percussive mechanism transmitting back forces via said wobble disc means when the work tool is pressed against a workpiece.