GB642285A - Improvements in or relating to spring balances - Google Patents

Abstract

642,285. Spring balances. LEER, W. VAN. June 18, 1948, No. 16445. [Class 143] A weighing scale with a rotary indicator has two selectable weighing ranges wherein the load is counterbalanced either by one spring or by that spring together with another spring. The pan 28 is secured to a stem 25 on a frame 13 which is guided by pairs of parallel links 14, 15 and 18, 19 and movement of this frame is communicated through a rack 9 to a pinion 8 on the same shaft as an indicating pointer 7 An arm 30, pivoted to the casing at 31, has a forked enc 32, 33 from which depend a pair of light load springs 34 per manently secured to the frame at their lower ends, and an arm ,40, pivoted to the casing at 42 supports the top of the heavy spring 51 from the bottom o: which depends a stirrup 54 When the parts are as shown this stirrup engages the lower member 35 of the frame so that both the light and heavy springs counterbalance the load, but, when the arm 40 is moved into a position 40<SP>1</SP>, the stirrup is disengaged from the member 35 so immobilising the spring 51 and allowing the light springs only to counterbalance the load. Zero adjustment screws 39, 47 are provided for each of the springs and movement of the screw 47 along a slot (not shown) in the casing to the position shown chain dotted effects movement of the arm 40 and thus the change in weighing range.