Abstract: An apparatus for selecting between a mechanical or electrical mode for controlling the flow of fibers by motor driven feed lift aprons from a plurality of hoppers to a plurality of weigh pans for producing a predetermined blend of fibers. The mechanical mode utilizes a balance arm assembly which can be set to feed a predetermined amount of fibers into a weigh pan. The electrical mode utilizes thumbwheel switches which can be set for regulating the amount of fibers to be fed into each weigh pan. The electrical mode system also utilizes a comparator for comparing a signal representing the actual weight of fibers in the weigh pan that is produced by a load cell with a signal representing the desired weight of fibers produced by the thumbwheel switches and generates a control signal responsive thereto. The control signal is used for operating a motor driven feed lift apron associated with the hopper.

Abstract: An apparatus for selecting between a mechanical or electrical mode for controlling the flow of fibers by motor driven feed lift aprons from a plurality of hoppers to a plurality of weigh pans for producing a predetermined blend of fibers. The mechanical mode utilizes a balance arm assembly which can be set to feed a predetermined amount of fibers into a weigh pan. The electrical mode utilizes thumbwheel switches which can be set for regulating the amount of fibers to be fed into each weigh pan. The electrical mode system also utilizes a comparator for comparing a signal representing the actual weight of fibers in the weigh pan that is produced by a load cell with a signal representing the desired weight of fibers produced by the thumbwheel switches and generates a control signal responsive thereto. The control signal is used for operating a motor driven feed lift apron associated with the hopper.

Abstract: A grid wire for use in a duct for imparting ions in the air flowing through the duct responsive to a voltage being placed on the grid. The grid includes a housing which has upper, lower and intermediate horizontally extending supports carried therein. Laterally spaced grid wires extend between the upper and lower support members. Screw means are provided for securing the grid wires to the intermediate non-conductive support members so as to minimize the length of the free swinging portion of the wire in case the wire breaks. By making the intermediate support member non-conductive a more uniform discharge of ions is produced by the grid.