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Performance of onboard weighing systems on sugar cane transport vehicles

2012-05-10 11:35   Article Source:N/A   View Times:
Abstract
To minimise the cost of transporting sugarcane it is important to optimise the payload. Overloading the vehicle will damage the roads and the vehicle, and compromise safety. There is also the risk of prosecution. Underloading the vehicle will result in lost revenue and increased costs. There are two aspects to loading a vehicle; one is to ensure that the gross mass is correct, and the other is to ensure that the load is correctly distributed between the various axles. These objectives are difficult to achieve with a crop such as sugarcane, where the bulk density of the material varies substantially. Other industries with similar problems, such as the timber industry, have settled on load-cell based ‘onboard?weighing systems as the only practical answer to the problem.
One year of data from a sugarcane grower and haulier in the Sezela area has been analysed to assess the suitability of using an onboard weighing system in a sugarcane haulage operation. The results have been compared with a vehicle that has an airbag suspension with a simple weighing mechanism, and a vehicle with spring suspension and no weighing system.
The conclusion is that the onboard weighing system achieves the desired load far more consistently than the airbag system, which in turn is more consistent than the spring suspension. The ablity to consistently achieve maximum payloads means that the cost of the onboard weighing system can be recovered over one or two seasons.
Keywords: sugarcane, transport, onboard weighing, payload, overload, load-cell
Introduction
In order to consistently load a vehicle optimally, it is essential to have an accurate measurement system as an indicator of both the gross vehicle mass of the vehicle and individual axle weights. In this way it may be possible to minimise both overloading (and avoid prosecution) and underloading (and save money). Available systems include:
• portable vehicle scales
• weighbridges
• pressure gauges on airbag suspensions
• onboard weighing systems.
Onboard weighing systems have been successfully implemented in the timber industry and are possibly the most cost-effective and accurate systems presently available in South Africa.

At a 2005 SASTA Workshop, a presentation dealing with onboard weighing systems (Cole,
2005. gave a comparison of gross vehicle mass of 78% of all loads delivered to Sezela mill during the 2004 season. This included data from any vehicle that operated 24 hours a day, six days a week and consistently delivered sugarcane loads to Sezela mill. A comparison was made of the gross vehicle mass of loads achieved by three vehicles, one fitted with an onboard weighing system, one with air suspension and an air pressure gauge and one with spring suspension and no weighing system. It was shown that the onboard weighing system was a cost-effective tool to optimise sugarcane loading.
Data used for this report relates to sugarcane loads carried by three vehicles from two farms during 2005. Two of the vehicles used were fitted with onboard weighing systems supplied by Loadtech (Pty) Ltd, and were used to transport 95% of the loads. The third vehicle, without a weighing system, was used sparingly during the 2005 season (5% of all loads). Data regarding this vehicle has been included, however, since the number of loads transported was very limited, it has been considered separately.
The data used in this report included weighbridge slips from Sezela mill as well as printouts from the Loadtech onboard weighing systems. There were a number of loads where no Loadtech printouts were available. For these loads, it is not certain as to whether or not the weighing system estimations have been used. For this reason, these loads have been considered separately from the loads where weighing system printouts were made. Drivers were instructed to aim at loading between 56 tons and 58.8 tons, without having individual axle overloads.
For all loads analysed, a Bell loader was used at a loading zone to load loose cane onto each vehicle. This ensured that it was possible to evenly spread the load across each axle.



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