Patent ID: 7441442

Claim:
A system for determining the forces acting on a movable member in which the member is suspended out of contact with any stationary component of the system and entirely surrounded by a sample of material to be tested between which and the movable member forces are exchanged in use of the system, the system comprising: an outer housing; a cylindrical sleeve for retaining the sample of material, said sleeve disposed within said outer housing; a rotor forming the movable member and disposed for concentric rotation within the sleeve; means for supplying the sample of material to be tested at a pressure to the interior of the sleeve; means for supplying a pressurized fluid to the outer housing to surround the sleeve and balance the pressure of the sample of material to be tested within the sleeve; magnetic contactless bearings disposed within the housing outside the sleeve to suspend the rotor within the sleeve; a stator disposed within the housing and outside the sleeve to impart a turning moment to the rotor; and means disposed within the housing and outside the sleeve for sensing the radial and angular position of the rotor.