Damping device having controllable resistive force

A damper assembly is provided including a linear to rotary motion conversion mechanism having an outer tube member. An inner tube member is reciprocally movable and at least partially disposed within the outer tube member. The inner tube member is adapted for linear translation in a first and a second direction. A rotatable shaft is disposed within the inner tube member. The translation of the inner tube member produces a rotation of the shaft. Also included within the damper assembly is a damping mechanism having a rotor fixed to the shaft. A coil is configured to generate an electromagnetic field in response to an applied current. A magneto-rheological fluid is in contact with the rotor, and has a variable viscosity in the presence of the electromagnetic field that, in turn, provides variable resistance to rotation of the rotor and translation of the inner tube member within the outer tube member.