WORKING PRINCIPLE OF DOUBLE SHEAR BEAM LOAD CELL
Double shear beam load cells are used to measure compressive forces. This type of load cell is a variation of the shear beam load cell, normally rated for higher loads. In double shear beam load cells, the force acts on the centre of the device. This makes double shear beam load cells less sensitive to uneven loading. The core element of the load cell is a spring element, consisting of a metal part that is elastically deformed under load and recovers when the force is no longer applied. This deformation or strain is picked up by strain gauges installed on the metal element and converted into an electrical signal. Double shear beam load cells contain two such spring elements and are calibrated for grams, kilograms or tons.
Double shear beam load cells are commonly found in heavy-load scales in the range of multiple tons and are thus most suitable for silo scales, container scales, vehicle scales and weighing frames. Double shear beam load cells are also used for force measurement in testing machines.
As double shear beam load cells are primarily used in industrial applications, they are designed to withstand adverse operating conditions and are generally rated IP67 or IP68. This means that the load cells are protected against dust ingress, splash water and even immersion (IP68 only). To identify the most suitable load cell for a particular application, the following parameters must be considered: rated load, limit or breaking load and minimum scale division for the calculation of the permissible tare weight. These specifications are found in the data sheet of the load cell. As load cells are generally impedance-trimmed (calibration of current output), multiple cells can be installed in parallel without the need for subsequent device calibration. In addition, most load cells are compatible with models from other manufacturers. Verifiable weighing equipment must of course be equipped with verifiable load cells.