On-board axle weighers are devices which can be fitted to vehicles to show the weight carried by each axle. Accurate and reliable on-board axle weighing systems would enable operators to load their vehicles fully without overloading axles. This should encourage efficient vehicle usage whilst reducing avoidable road wear. A feasibility study of methods of on-board weighing concluded that the most promising method would be to measure the vertical shear strain in the axle between the suspension and the wheel. Strain-gauged transducers were designed and were tested on a rig which simulated the loads imposed on an axle. Their performance was compared with that of strain gauges mounted directly on the test axle. The results suggest that directly mounted strain gauges could give weight indication accurate to within 100 kg per axle when the vehicle is on a flat level surface. Slight gradients and surface unevenness would reduce the accuracy by a further 50 kg per axle. Although the output of the strain-gauged transducers was larger than that of the directly mounted strain gauges, it was less consistent and more susceptible to other strains in the axle, resulting in lower overall accuracy. (A)

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