Black Decker Inc.

Rene Gumpert

Heinz-Werner Faatz

Tim Heimrich

Bruno Meinholf Ruethers

Petr Dusik

Horst Grossman

A hammer drill is provided including a motor, an electrical power circuit arranged to provide power to the motor, a tool holder arranged to hold a cutting tool, and a drive transmission operable in at least two modes of operation. A mode change mechanism is provided to switch the drive transmission between the at least two modes of operation, and at least one electrical switch is located within the electrical power circuit to provide power to the motor. Hammer drill further includes lock-on mechanism is configured to lock the at least one switch in the closed state when it is activated, a controller configured to control an operation of the motor, and an electrical power circuit configured to provide power to controller. The motor is prevented from operating when no power is provided to the controller.

Hammer drill

A motor driven hammer having a housing, a motor having a motor shaft and being arranged in the housing, a hammer mechanism including a cylinder in which a ram is arranged the ram being slidable along a longitudinal axis (L) of the cylinder, and a tool holder which may support a tool bit so that the tool bit is aligned with the longitudinal axis of the cylinder, wherein the motor is coupled with the hammer mechanism, so that rotation of the motor shaft results in a reciprocating movement of the ram within the cylinder, the ram applying impacts on a tool bit supported by the tool holder during the reciprocating movement. Further, the ram is made of a paramagnetic or ferromagnetic material or comprises a permanent magnet and a coil is arranged within the housing adjacent to the cylinder so that the coil applies a force in the direction of the longitudinal axis on the ram if a current is applied to the coil.

Motor driven hammer having means for controlling the power of impact

A speed adjustment mechanism for a power tool is disclosed. The mechanism includes a support, a first toothed gear for rotation by means of an adjustment dial, and a second toothed gear rotatable by means of the first toothed gear and connected to a potentiometer which is connected to a speed control circuit. Limited movement of the first and second toothed gears relative to each other is possible to reduce transmission of impacts from the adjustment dial to the speed control circuit.

Control mechanism for a power tool

A powered hammer is described comprising a housing, a tool holder mounted on the housing, a percussion mechanism arranged within the housing which mechanism includes a ram reciprocating in a longitudinal direction and being adapted to apply impacts on a tool bit supported in the tool holder, a dampening mass which is slidably mounted in the longitudinal direction within the housing, wherein the dampening mass is biased towards a neutral position by a biasing element and wherein the dampening mass may be deflected from the neutral position against the biasing force of the biasing element. The dampening mass is formed of a ferromagnetic or paramagnetic material or comprises a permanent magnet and a solenoid is arranged within housing adjacent to the dampening mass such that the solenoid applies a force in the longitudinal direction on the dampening mass when being in the neutral position if a current is flowing through the solenoid.

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Schoeneck, Germany

Rene Gumpert