Patent ID: 7654907

Claim:
An apparatus for damping a torsional excitation of a drive shaft, comprising: a tube extending along the drive shaft having one end secured to the drive shaft; a first actuation lever and second actuation lever extending from an end of the tube opposite the end secured to the drive shaft, the first and second levers located on opposite sides of the tube; a hydraulic damper for damping vibration of the first and second actuation levers, comprising: a first pair and second pair of hydraulic cylinders, each hydraulic cylinder having a piston, and a fluid flow path between the cylinders, wherein the first pair of hydraulic cylinders are arranged so that the actions of the pistons of the cylinders oppose one another in a dimension of vibration of the first actuation lever, the pistons communicating with the first actuation lever, wherein the second pair of hydraulic cylinders are arranged so that the actions of the pistons of the cylinders oppose one another in the dimension of vibration of the second actuation lever, the pistons communicating with the second actuation lever, and wherein the torsional excitation of the tube causing vibration of the first and second actuation levers resulting in a fluid flow between the cylinders to damp the vibration.