In a vibration damping device 20, the moment of inertia J.sub.1 of a driven member 15, the moment of inertia J.sub.2 of an inertial mass body 23, the mass m of crank members 22, the distance L3 between the center of gravity G of the crank member 22 and the fulcrum of swinging of the crank member 22 with respect to the inertial mass body 23, and the distance L4 between this fulcrum and the center of rotation RC are determined so that torque fluctuation of an object for which vibration is to be damped, which is derived based on angular displacement and angles obtained by solving an equation of motion for the driven member 15 and an equation of motion for the entire vibration damping device 20 is equal to a target value.

In a vibration damping device 20, the moment of inertia J.sub.1 of a driven member 15, the moment of inertia J.sub.2 of an inertial mass body 23, the mass m of crank members 22, the distance L3 between the center of gravity G of the crank member 22 and the fulcrum of swinging of the crank member 22 with respect to the inertial mass body 23, and the distance L4 between this fulcrum and the center of rotation RC are determined so that torque fluctuation of an object for which vibration is to be damped, which is derived based on angular displacement and angles obtained by solving an equation of motion for the driven member 15 and an equation of motion for the entire vibration damping device 20 is equal to a target value.

The dual mass flywheel comprises a spring assembly (4; 104; 112; 128; 129), if necessary, with two stages of which one can include a spiral spring. Furthermore, the dual mass flywheel comprises a friction damping system (111) that applies torque independently of the rotational speed of the flywheel.

The dual mass flywheel comprises a spring assembly (4; 104; 112; 128; 129), if necessary, with two stages of which one can include a spiral spring. Furthermore, the dual mass flywheel comprises a friction damping system (111) that applies torque independently of the rotational speed of the flywheel.

A torsional damper assembly for a vehicle powertrain is provided and is configured to dampen torsional vibration transfer between an engine and a transmission of the vehicle. The assembly includes a hub having a flange defining a window, a biasing mechanism disposed at least partially within the window and configured to absorb a first portion of the torsional vibration from the engine, and a damper body disposed at least partially within the window. The damper body is formed from at least one of a viscoelastic material and a viscoplastic material, and is configured to dampen a second, different portion of the torsional vibration and radial forces from the engine such that the biasing mechanism and the damper body cooperatively dampen the torsional vibration transfer between the engine and the transmission.

An antenna for satellite communication includes; a signal transmitting and receiving unit for receiving or transmitting a signal from/to the satellite; a driving unit for rotating the signal transmitting and receiving unit so as to enable the signal transmitting and receiving unit to track the satellite; an anti-vibration unit provided inside the posts for elastically supporting the signal transmitting and receiving unit or the driving unit. Therefore, by providing the anti-vibration unit inside the posts, it is possible to increase availability for a circumferential space of the posts and to simplify the structure of the anti-vibration unit.