Patent ID: 7563018

Claim:
A mixing device for producing bone cement comprising: a mixing space ( 6 ) for mixing components ( 4 , 5 ), said mixing space ( 6 ) including at least one piston ( 9 ) which can be brought to remain in a start position (A) at or adjacent a first end portion ( 8 ) of said mixing space ( 6 ) during mixing and which is releasable therefrom after mixing, said piston ( 9 ), after being released, being sucked towards a second end portion ( 10 ) of the mixing space ( 6 ) by a vacuum prevailing therein, and at least one throttle device ( 20 ) and a closing device ( 23 ), wherein the throttle device ( 20 ) and the piston ( 9 ) define an intermediate space ( 21 ), the closing device ( 23 ) and the throttle device ( 20 ) define an outer space ( 33 ), and the intermediate space ( 21 ) communicates with the surroundings through the outer space ( 33 ), wherein the throttle device ( 20 ) can be closed by the closing device ( 23 ) for air-tight isolation of the piston ( 9 ) from the surroundings in order to bring the piston to remain in the start position (A) during mixing, wherein the throttle device ( 20 ) is opened to release the piston ( 9 ) from the start position (A) and by generating a pressure drop between the air pressure in the surroundings and the piston, preventing full power affection thereof by said air pressure after said piston is released.