Demolition hammer and/or hammer-drill with a percussion device suitable for releasing clamped objects by striking

A demolition hammer and/or hammer drill for working a material, comprising:

• a tool having a tool shaft which is movable over a limited axial path;
• a percussion generating device which comprises an axially reciprocatable percussion;
• and
• a percussion changing device, including:
• a force detection device configured to detect a pulling force which acts upon the tool when the tool is jammed in the material being worked and which is generated by pulling on the demolition hammer and/or hammer drill, and
• a switching device configured to cooperate with the force detection device for the purpose of switching over from a main percussion state to a free percussion state,
• wherein, in the main percussion state, the percussion piston influences the tool shaft of the tool directly or via an intermediate element in a main percussion direction,
• wherein, in the free percussion state, the percussion piston does not influence the tool shaft directly, but rather influences the percussion changing device so as to influence the tool indirectly in a free percussion direction which is opposite to the main percussion direction,
• wherein it is possible to switch over from the main percussion state to the free percussion state if the tool is jammed in a material being worked,
• wherein the switch over to the free percussion state is performed if the pulling force exceeds a predetermined threshold value,
• wherein a first part of the percussion changing device can be displaced in the free percussion state into an effective region of the percussion piston by means of the tool which can be pulled along the axial path out of the demolition hammer and/or hammer drill,
• wherein, in the main percussion state,
• a free percussion ram, which forms a first part of the percussion changing device, is removed from an effective region of the percussion piston by an effect of a return spring forming the force detection device, and
• at the same time, the percussion changing device is pretensioned under the effect of the return spring in such a manner that an extension, that forms a second part of the percussion changing device protrudes into a movement path of a stop which is provided on the tool, and
• wherein, in the free percussion state,
• by reason of its changed axial position, the stop of the tool influences the percussion changing device against the effect of the return spring and displaces an impact surface of the free percussion ram into the effective region of the percussion piston when a spring force is overcome.

A demolition hammer and/or hammer drill for working a material, comprising:

• a tool having an axially movable tool shaft;
• a percussion generating device having an axially reciprocatable percussion piston;
• and
• a percussion changing device, the percussion changing device including
• a force detection device which detects a pulling force which acts upon the tool when the tool is jammed in the material being worked and which is generated by manually pulling on the demolition hammer and/or hammer drill, and
• a switching device which is responsive to operation of the force detection device to switch over the percussion piston from a main percussion state to a free percussion state when the force detection device detects that the pulling force exceeds a threshold value,
• wherein, in the main percussion state, the percussion piston at least indirectly drives the tool shaft to move a main percussion direction, and
• wherein, in the free percussion state, the percussion piston at least indirectly drives the tool shaft to move in a free percussion direction which is opposite to the main percussion direction.