Rock Products

JUL 2013

Rock Products is the aggregates industry's leading source for market analysis and technology solutions, delivering critical content focusing on aggregates-processing equipment; operational efficiencies; management best practices; comprehensive market

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LOADOUT TRANSPORTATION CARDINAL SCALE'S GUARDIAN HYDRAULIC TRUCK SCALES Cardinal Scale's Guardian Hydraulic Truck Scale offers weighing accuracy and longevity in hostile environments, according to the company. The USAmade Guardian is impervious against lightning and water damage, two of the most common issues to affect electronic load cell truck scales. These NTEP legal-fortrade truck scales are available in concrete or steel decks and low-profile or pit mount types up to 135 tons. The Guardian carries a true lifetime load cell warranty. Cardinal Scale is a singlesource provider for all of the components in the Guardian from the model SST stainless steel hydraulic load cells to the truck scale weighbridge and totalizer to the remote display and digital weight indicator. Cardinal Scale, Advanced Scale Systems Improve Aggregate Operation Efficiency and Increase Production By Larry Behrens Electronic scales are available in many dif‐ ferent configurations to meet diverse appli‐ cation requirements. Though they come in many forms, electronic scale systems deliver dependable accuracy in a rugged, convenient package. From material collection to pro‐ cessing, storage and sale, users will find a suitable scale for each stage of aggregate production. The heart of an electronic scale is the load cell weight sensor, which converts force measurements into an electrical signal read by a connected weight indication system. The most common style of load cell is based on the cantilever principle, where one side of the cylindrical device is fixed and the other suspended. A load – in this case, either a ve‐ hicle carrying aggregate materials or the ag‐ gregate alone – is placed on the suspended end, which absorbs the force of the applied load. This force measurement is translated as the load's weight. One particularly effective style of load cell operates using two pairs of electronic sen‐ sors, also called strain gauges, placed on the outside of the load cell structure – one on top and one on the bottom. The advantage of two sensor pairs is demonstrated when load placement varies in position atop the load cell, or when various types of loading errors occur such as end loading, side loading and torsion effect. The sensor arrangement en‐ sures uniform compressive strain through‐ out the full load cell structure, delivering consistent readings despite these variances. This load cell may be incorporated into many types of scales, including a truck scale. An electronic load cell may also be inte‐ grated into aggregate processing and han‐ dling equipment, such as conveyors and front‐end loaders, to deliver accurate mate‐ rial weighing and tracking from aggregate collection to sale. Tracking Raw Material Typically, an aggregate producer will weigh company trucks and program the connected digital weight indicator to store the weight, as well as any pertinent data such as truck number or driver ID, for each vehicle. This arrangement facilitates one‐time weighing: A driver returns from the quarry with the ag‐ gregate load and, once prompted, enters a driver ID via the indicator's keypad. This ID is associated with the empty truck weight taken earlier, which now serves as a tare weight. The truck is then weighed full, and the indicator generates the net weight of the load. The indicator is often accompanied by a printer as well, allowing drivers to print a receipt immediately after the transaction. An alternative, simpler solution utilizes the weight indicator as basically a local display: The indicator will merely gather and convey the truck's weight so that it can be manually documented. To measure the amount produced of each grade, a belt scale can be used to obtain the weight of the aggregate materials during the transport process. In this arrangement, load cells replace the idlers in the traditional con‐ veyor design. As aggregate travels down the conveyor belt, the belt scale obtains the weight of all material crossing the load sensors. This weight data is gathered by the belt scale's indicator, which also tabulates the ag‐ gregate produced to determine a total. Users can document the total weight by hand, or the indicator can communicate the weight data directly to the aggregate producer's in‐ ventory system. Since each belt scale is used for a different grade of aggregate, the weight information collected can be easily catego‐ 30 ROCKproducts • JULY 2013

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