Device for damping the vibration of a structure

A device for damping vibration of a structure, the device comprising:

• a support having one end held fixedly in the structure;
• a main mass fastened to the support;
• an auxiliary mass mounted on the support, said auxiliary mass including a primary mass and a secondary mass, wherein the secondary mass is arranged in a groove of the primary mass;
• a casing mounted on the support, wherein the auxiliary mass is disposed and movable within the casing;
• a spring positioned to bias the primary mass away from the secondary mass thereby pressing the primary mass against a first inside surface of the casing and pressing the secondary mass against a second inside surface of the casing;
• a drive screw engaging the auxiliary mass along a longitudinal axis parallel being offset from an axis of symmetry of the auxiliary mass;
• and
• a manual drive means engaging and actuating the drive screw to move the auxiliary mass along the drive screw thereby moving the center of gravity of the device to modify the resonant frequency of the device.