Abstract: A rotary actuator assembly for positioning read/write heads in disk drive mass storage systems. The actuator assembly includes an actuator motor and one or more actuator arms secured thereto. The motor provides rotary motion of the arms, to move the heads. The stator magnet of the motor is an electromagnet wound on an arcuate core; a pair of elongate permanent magnets are attached to the rotor member, for coaction with the stator magnet. The rotor member has a U-shaped cross sectional area in a plane perpendicular to its axis of rotation; the permanent magnets are fixed to the outside, bottom corners of the U and the actuator arms are mounted across the open end of the U. The rotor is of a very small radius, to minimize inertia. The permanent magnets have a flat face facing the stator, with a channel running longitudinally down the middle, to minimize flux density variations in the permanent magnet-coil gap. The rotor balances the arm relative to the rotor's axis.

Abstract: An external combustion engine, such as the vapor cycle engine, produces power by the expansion of a working fluid vapor. A vapor generator vaporizes a suitable working fluid which is fed to an expander. The vaporized working fluid expands and is subsequently fed back to the vapor generator. A burner provides energy for the vapor generator. The fuel and air supply for the burner is controlled by a system responsive to operating conditions of the engine. That is, the power input to the vapor generator is correlated by a control system with the demand on the engine. The control system disclosed involves a servomechanism which may suitably respond, for example, to either the working fluid flow rate or the input from an accelerator which commands a change in the working fluid flow rate.