Abstract: Head positioning apparatus for a magnetic disk drive unit (10) including a disk pack portion (12) and a head-positioning portion (14), the latter employing a linear magnetic induction motor (22) for accurately positioning an associated head (20) relative to the disk pack portion (12) while permitting efficient assembly of the head-positioning portion (14) due to the arrangement of slide bearing shafts (30, 32) on the outside of the motor (22) and the use of an adjustable lever arm (38) and a bracket (48) at respective ends of the slide bearing shafts (30, 32). Fluid bearings are used throughout, with the disk pack portion (12) employing a fluid thrust bearing (88) in a means for coupling a plurality of disks (80) to an associated drive motor (86) in order to isolate the disks (80) from axial fluctuations of the motor armature (90) along its axis of rotation and prevent damage to the disks.

Abstract: A collapsible rebound exercise apparatus (10) as a resilient, flexible mat (12) capable of forming a substantially planar surface when an associated frame (14) supporting the mat has an open framework (16) thereof disposed in a substantially planar, open position. The framework is provided with two pair of hinges (18, 20) arranged perpendicularly to each other and which permit the framework to first fold symmetrically in overlying relation on itself, and subsequently to collapse on itself by pivotal movement perpendicular to the folding movement. Once folded and collapsed, the framework and associated mat form a generally rectangular package which can be placed in a suitable container, such as a flexible bag (32), for storage and transport.

Abstract: A read/write head-positioning apparatus for positioning one or more heads in a disk recorder and including a magnetic stator assembly having a coaxial, longitudinally-extending, annular coil-receiving cavity and a pair of longitudinally-extending, air bearing forming passageways provided therein, and an armature assembly including a pair of main bearing shafts disposed to pass through the passageways and a member affixed to the shaft ends for carrying a cylindrical coil support adapted to carry a drive coil within the coil-receiving cavity and for receiving the head-carrying arms. A pump is coupled to the stator assembly to create an air bearing flow in the passageways around the main bearing shafts so that electromagnetic interaction between the drive coil and the magnetic stator assembly can be used to position the recording heads with a minimum of frictional resistance.