Abstract: Disclosed is an input device for a computing machine which allows a user to input one, two, three, or more position signals controlling the same number of parameters. Such parameters can be the x, y, and z axis positions of a cursor on a display. The present invention includes structures for encoding the movement of the users fingers into position signals. The present invention is arranged so the differential movement of two of the user's fingers in a first plane generates one of the position signals. The differential movement provides that as a first finger is moved, a second finger is moved in an opposite direction and an amount proportional to the movement of the first finger. The differential movement of the user's fingers allows for more efficient, precise, and less tiresome operation by a user than with other input devices. Embodiments of the present invention can possess movement in one, two, three, or more, degrees of freedom and are able to generate one, two three, or more, position signals.

Abstract: A fluid power engine is disclosed. A pair of axially aligned and opposed combustion pistons oscillate in a pair of opposed cylinders. The pistons are connected to each other by a common axial shaft. A fluid power piston is adapted to the shaft and oscillates in a fluid cylinder. Upon oscillating action of the combustion pistons, the fluid power piston oscillates to produce fluid power. By means of a fluid power return assembly, a portion of the fluid power produced is returned to the fluid power piston to urge the combustion pistons in their return directions after their respective firing strokes. The fluid power return assembly includes a spool valve that is actuated by means of physical contact with the combustion pistons.