Abstract
Farm tractors are still widely used in many forestry operations. Predicting fuel and lubricant costs is difficult because their consumption depends on a number of factors such as hours worked and operations performed. Fuel and lubricant consumption is important since it can have an impact at both the economic and environmental level. Many fuel models have been studied in the last decades, but few studies have focused on oil consumption. The ASABE (American Society of Agricultural and Biological Engineers) Standard suggested a model for predicting engine oil consumption of farm tractors of the 1980s, which are potentially different from modern tractor engines. In addition, the recent widespread application of semi- and full-power-shift and continuous variable transmissions and the high number of hydraulic applications increased the amount of lubrication oil for transmission and hydraulic systems.For these reasons, we analysed 133 4WD recent model farm tractors used in forest operations with the aim to study:Þ engine, transmission and hydraulic system oil capacitiesÞ engine oil change intervals as recommended by the manufacturers.A new equation for engine oil consumption, as a function of the rated engine power, was first used and statistically analysed. It was similar to the equation developed by other authors (with a mean difference of 28%, decreasing to 11% at the highest engine power), but well below the ASABE model (with an average engine oil consumption three times higher). Another equation of total oil consumption related to the rated engine power was then studied and compared with a recent study. The results showed an average difference of 18%, decreasing to 8% at the highest engine power. The differences, due to a different machine dataset (only 4WD farm tractors that can be used for forestry operations were analysed) are, however, minimal also in the engine oil consumption model if compared with the oldest ones: a new proposal is therefore necessary, with new and affordable models for correctly evaluating economic and environmental forestry operation costs when using farm tractors.
Highlights
Despite the use of custom built forestry machines, rubber-tyred farm tractors are still widely used in small-scale forestry in various sites and in non-industrial private forestry, where specialised forest-addressed machines may not be viable for the terrain morphology (Marchi et al 2014, Spinelli and Magagnotti 2009, Spinelli et al 2010) or for economic and environmental reasons (Spinelli and Magagnotti 2012, Šušnjar et al 2008, Beuk et al 2007)
The study concerned only rubber-tyred tractors. We compared both the engine and the total oil consumption with the results found by Calcante et al in 2017 and 2019, with the aim to evaluate possible differences when considering farm tractors for forestry operation purposes
Despite a wide variability in the capacity of the oil pans and oil service intervals, this study showed a good correlation between the engine rated power with both the engine and the total oil consumption in 4WD farm tractors used in forest operations
Summary
Despite the use of custom built forestry machines, rubber-tyred farm tractors are still widely used in small-scale forestry in various sites (mountain areas, steep hills, urban forestry sites) and in non-industrial private forestry, where specialised forest-addressed machines may not be viable for the terrain morphology (Marchi et al 2014, Spinelli and Magagnotti 2009, Spinelli et al 2010) or for economic and environmental reasons (Spinelli and Magagnotti 2012, Šušnjar et al 2008, Beuk et al 2007). The mechanisation cost of these machines is lower than that of specialised forestry equipment, their owners are interested in the estimation of the operating costs (Bright 2004, Nordfjell et al 2010, Röser et al 2011, Spinelli and Magagnotti 2012, Gilanipoor et al 2012). These costs are related to the use of the machine (Hawkins and Buckmaster 2015). At the end of the 1990s, Siemens and Bowers found that the cost of fuel and lubricant for a farm tractor ranged between 16 and 45% of the total cost of the machine
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