A portable vehicle weighing unit is necessary for axle-load surveys in pavement design as well as for enforcing legal load limits on highways. In many parts of Brasil the conventional static weighing bridges are almost non-existent and overloading of vehicles is quite common. A portable electronic weighing unit based on strain gage load cells has been developed which is battery operated and can weigh loads of upto 10 tonnes to better than ± 5% accuracy. The principle involved is the conversion of the wheel load into a mechanical deformation of the load cells which in turn is converted into an equivalent electrical signal by bonded strain gages on the load cells. This output signal is amplified using integrated circuit operational amplifiers. The prototype developed has shown satisfactory performance in laboratory tests. While such electronic weighing units are already in use in industrialised countries, the present development, it is felt, is the first attempt in Brasil at developing this technology indigenously.
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