GB739278A - Improvements in and relating to load measuring means - Google Patents

Abstract

739,278. Load measuring gauge. NATIONAL RESEARCH DEVELOPMENT CORPORATION. March 5, 1954 [Dec. 5, 1952], No. 30986/52. Class 40 (1). A load measuring gauge comprises a hollow ring of elastic material through which the load is transmitted in a direction normal to the plane of the ring, having at least one resistance strain gauge fixed to the outer or inner periphery to respond to the circumferential strain. Circular section steel ring 11 has four strain gauges of equal resistance fixed on it, two 22 extending around almost the entire outer periphery and being connected in opposite arms of a bridge circuit, and the other two 21 extending around the inner periphery and connected in the remaining arms. Connection to the inner gauges, which have more limbs than the outer to compensate for their shorter length, is through diametral hole 24. Load is applied to the ring through a pair 12, 13 of steel plates with annular grooves into which the ring fits, the groove being sealed by cork packing ring 14 and rubber band 15. The plates are held together by nut and bolt 16, 17 bearing on resilient washers recessed into the plates. Balancing resistor 23 is also mounted on plate 13. The strain gauges which are of wire, e.g. of metals known under the Registered Trade Marks " Nichrome " or " Eureka," on paper bases are applied by means of phenol formaldehyde resin diluted with alcohol and are then covered with the undiluted resin, bound with tape and the whole then cured. The ring 11 may be of elliptical or lenticular cross-section with the major axis parallel to the load. The working range is proportionately increased by using a thin walled ring of material with a high ratio of elastic limit to elastic modulus, e.g. alloy steel or that known under the Registered Trade Mark K. " Monel " metal.