TOP-LOADING PRECISION BALANCE

摘要

The magnet system of a top-loading precision balance with electromagnetic load compensation is fixedly fastened in an aluminum alloy frame constituting the fixed link in the parallelogram suspension for the weighing pan. Distortion of the frame resulting from variations of temperature of its ferrous magnet system and the light metal, e.g. aluminum or other light metal non-magnetic alloy of the frame, with consequent different dimensional changes, is prevented by openings formed in the frame walls spacedly surrounding those portions of the frame side walls fastened rigidly to the magnet system. A sheet metal frame has three upright wall portions which in plan constitute a rectangle; the longer opposed side walls are supported by a ferrous magnet body to which the walls are bolted. A parallelogram linkage pivots by two pairs of laterally and vertically spaced resilient strips secured to a rigid end wall of the frame, allowing the weighing pan to move vertically without twist or inclination. The pan displacement is converted to rotation of a lever arm by a suspension carried in the frame end wall remote from the rigid end wall. The opposed side wall portions are apertured or thinned so that the magnet body expansion does not distort the sheet metal frame and alter the support point of the lever arm suspension.