Abstract: A ferrofluid centrifugal seal and method of sealing a rotatable shaft, wherein ferrofluid is retained in an O-ring-seal form at static and low speeds and is moved to a barrier seal in a passageway at high speeds.

Abstract: A seal for rotatable shafts utilizes a ferrofluid as a sealant and lubricant. As a sealant, the ferrofluid acts to exclude particulate matter from passing through the seal area contaminating internal mechanism elements, while as a lubricant, the ferrofluid forms a film between the shaft and the elastomer-material seal element; thus, cooling and lubricating the contact interface and acting to extend the life of the related components. The seal assembly has permanent magnetic elements which create a magnetic-field gradient, causing magnetic-field maxima at points immediately surrounding the contact point between the seal-elastomer material and the shaft. The ferrofluid is entrained magnetically within the interface region; thus, insuring continual lubrication of the contacting surfaces, while further, the entraining forces prevent leakage of the ferrofluid from the region.

Abstract: A viscous-fluid inertia damper, which damper comprises a housing composed of a nonferromagnetic material and having a chamber therein, a seismic mass containing a permanent magnet disposed in the housing chamber and in a closely spaced-apart relationship with the internal wall surface of the chamber, means to couple the housing to a dynamic element whose energy is to be dampened, and a ferrofluid of selected viscosity in the remaining volume of the chamber, the ferrofluid distributed generally uniformly in the volume, the magnetic saturation of the ferrofluid by the magnetic field of the permanent magnetic levitating the seismic mass in the damper, and the viscosity of the ferrofluid in the magnetic field providing a means to dissipate energy from the dynamic system through viscous shear forces in the ferrofluid disposed between the wall surface of the chamber and the seismic mass.