Patent ID: 8579311

Claim:
A damper assembly for damping movement of a damper mass, the damper assembly comprising: a rod extending along a longitudinal axis between a first end and a second end; a casing disposed annularly about and in sealing engagement with the rod to define a primary fluid chamber between an interior surface of the casing and the rod; wherein the casing is moveable relative to the rod along the longitudinal axis; a piston fixedly attached to the rod and disposed within and dividing the primary fluid chamber; wherein the rod includes an annular wall extending along the longitudinal axis to define a first expansion chamber extending along the longitudinal axis; wherein the rod defines a first expansion port extending radially through the annular wall of the rod to connect the first expansion chamber and the primary fluid chamber in fluid communication; a first spring coupled to the rod and configured for opposing movement of the casing relative to the rod in a first direction along the longitudinal axis; and a second spring coupled to the rod and configured for opposing movement of the casing in a second direction along the longitudinal axis, wherein the first direction is opposite the second direction.