Wide-range load cell

摘要

A wide-range load cell is installed within a press in line with the work load. The load cell measures the actual force applied to the load irrespective of any friction, binding or drag in the press mechanism. The sensitivity of the load cell is adjusted in order to provide an accurate measurement over a wide range of pressures. In some embodiments of the load cell the least sensitive of the pressure or traction bearing elements become active as the applied force approaches the maximum limit of the more sensitive element. In other embodiments of the invention the most sensitive of the pressure or traction sensing elements are switched out of operation as the applied force approaches their maximum limits. A hydraulic version of the load cell uses a combination of pressure-sensing transducers of different ranges and sensitivities. An alternate mechanical version of the load cell is based on a plurality of concentric force rings of different heights which are sequentially subject to the force of the press as the tallest and usually most sensitive amongst them are being deflected to the level of the next shortest cylinder.