GB868824A - Improvements in automatic weighing means - Google Patents

Abstract

868,824. Electric measuring systems. SIMON Ltd., HENRY, and RICHARDSON SCALE CO. March 11, 1958 [March 26, 1957], No. 9822/57. Class 40 (1). In an automatic feed weigher which batch weighs a number of different constituents in a single weigh pan utilizing a resistance bridge circuit comprising fixed resistors in two of the arms, cyclically selected pre-set resistors CP1, CR1, &c. in the third arm, and a variable resistor P controlled by the weighing mechanism in the fourth arm, the quantity of a particular constituent as determined the preset resistors is modified by a relay MC controlled by the main cyclically operating switch, which opens its contacts mc2 at the appropriate step on switch bank 3 to introduce an auxiliary resistor CR in accordance with known impurities in the constituent. The auxiliary resistor CR is controlled by a second resistor bridge 11 in which one arm 12 is adjusted to the weight of the particular constituent as preset into the main bridge, another arm 13 is preset in accordance with the proportionate weight increase required to compensate for the impurity, the third arm is a fixed resistor and the fourth arm 14 is automatically adjusted by motor 15 which simultaneously adjusts the auxiliary resistor CR. If the impurity is itself one of the main constituents, e.g. water in sand when weighing the constituents for concrete, the preset resistor for the impurity as a separate constituent can be reduced by the same setting of the second bridge 11. Specifications 779,356, 839,626 and 868,823 are referred to.