How do truck scales work?

The entire steel platform is mounted on load cells. Each load cell is comprised of a durable material such as steel or concrete with one or more strain gauges attached to or embedded in it. A strain gauge consists of a wire (or wires) that transmits a mild electric current.

As the cell is subjected to weight, the wire in the load cell strain gauge is altered or compressed slightly. The change in the wire results in a difference in the resistance to the current passing through it.

The analog signal from each load cell is sent to the junction box. Junction box combine the signals of multiple load cells and then transmit the summed signal to weighbridge controller. The controller digitizes the signal from the junction box using analog to digital converter (ADC) and weigh is registered on LED display.

The weight of the payload, including the weight of the truck, is measured by first driving the truck onto the weighbridge; this weight is referred to as the gross weight. To obtain the weight of the payload (the net weight) the tare weight (the weight of the empty truck) must then be subtracted from the gross weight.