Abstract: A piston pump mechanism for use in positive pressure and vacuum pumping systems for pumping various gases such as air, freon, natural gas, etc. The pump mechanism incorporates an inlet and discharge valve system that substantially eliminates any unpurged or unswept volume of gas within a pump cylinder during each reciprocating stroke of the pump piston. The pump mechanism also incorporates a control spool that floats within a pump head and has a sealed flexible interconnection with the discharge valve that allows the discharge valve to seek optimum seating engagement about the entire periphery of the cylinder. The valve control spool may be pressure balanced or controllably unbalanced, as desired, for influence of the discharge valve. The spool also provides for inlet of gas to an inlet valve that may be incorporated into the discharge valve.

Abstract: A vegetation cutter and method employing a revolving flexible non-metallic line as a cutting member is provided with means for mechanically feeding out additional line to replace lengths broken during operation of the cutter. A rotatable spool is provided for storing extra line in a coiled configuration, with the unwound portion being extended from the rotatable head of the cutter to an exit aperture at its periphery. A control mechanism provides for moving angularly the spool an incremental distance within the rotating head to feed out an increment of line only when desired. Means secure the spool in the head to prevent inadvertent unreeling of cutting line.

Abstract: A centrifugal clutch mechanism according to the present invention includes a pair of spaced clutch shoes, one being a power shoe and the other being an energizing shoe, that are movably supported by a rotor element that is rotated by a drive source. A clutch housing having an internal cylindrical surface for mating engagement with the clutch shoes is connected to a rotatable driven element and is rotatable along with the rotor element responsive to forces transferred to the clutch housing from the clutch shoes. Clutch energization or expansion is induced by a centrifugally movable modulating arm having a cam roller that has operative engagement with a cam surface provided on the energizing shoe. Centrifugally induced movement of the modulating arm is controlled by a slippage control spring and by an anti-self-energizing spring.