Abstract: A torsional vibration balancer, especially for piston type apparatus having a secondary side seismic mass radially outside a primary member connected to a shaft to be damped. Damping boxes for the resilient and damped coupling of the seismic mass are attached, as replaceable components, to one of the secondary structural elements, preferably to a support disc for the seismic mass. At the interior of the damping boxes there is at least one fitted bolt or similar element, which extends under seal out of the damping box and is fixed to the primary member. This fitted bolt carries shear sheets which are plane parallel and perpendicular to the axis of rotation, and between which stationary metal sheets extend within and are connected to the damping boxes. The spaces between the shear sheets and the metal sheets are filled with silicon oil which is subject to alternate sheaving during relative movements of the sheets.

Abstract: A torsional balancer device for a rotary shaft such as for a piston engine comprises a rotationally symmetrical member which is adapted to be connected to the rotary shaft to be balanced. A rotationally symmetrical seismic mass is rotatably mounted so as to be closely spaced from the rotational member and a viscous damping agent is within the small gaps between the seismic mass and the symmetrical member.A plurality, preferably an odd number, of curved, substantially closed spring elements have closely spaced ends which are connected respectively to the rotational member and the seismic mass. The spring elements define closed curves which may be circular or elliptical in shape. The rotationally symmetrical member may comprise a hermetically sealed annular housing and the seismic mass and damping agent may be enclosed within the housing.

Abstract: A torsional balancer device for a rotary shaft such as for a piston engine comprises a primary mass mounted upon the rotary shaft and a secondary mass resiliently supported and mounted with respect to the primary mass so as to be capable of resilient rotational movement with respect thereto. The primary and secondary masses have mutually facing surfaces which define a working space and a viscous damping agent is in the working space. The mutually facing surfaces have profiled configurations so as to form a plurality of chambers the widths of which are varied during relative vibration of the secondary mass with respect to the primary mass. The configurations may comprise coregistering ribs and grooves which have various cross-sectional shapes.