Özet:

Purchasing and maintaining tractors and operating machines are two of the most considerable costs of the agricultural sector, which includes farm equipment manufacturers, farm contractors and farms. In this context, repair and maintenance costs (R&M costs) generally constitute 10-15% of the total costs related to agricultural equipment and tend to increase with the age of the equipment; hence, an important consideration in farm management is the optimal time for equipment replacement. Classical, R&M cost estimation models, calculated as a function of accumulated working hours, are usually developed by ASAE/ASABE for the United States operating conditions. However, R&M costs are strongly influenced by farming practices, operative conditions, crop and soil type, climatic conditions, etc. which can be specific for individual countries. In this study, R&M cost model parameters were recalculated for the current Italian situation. For this purpose, data related to the R&M costs of 100 4WD tractors with engine power ranging from 59 to 198 kW, and of 20 SP combine harvesters (10 straw walkers combines and 10 axial flow combines) with engine power ranging from 159 to 368 kW working in Italy were collected. According to the model, which was obtained by interpolating the data through a two-parameter power function (proposed by ASAE/ASABE), the R&M cost incidence on the list price of Italian tractors at 12,000 working hours (estimated life of the machines) was 48.6%, as compared with 43.2% calculated through the most recent U.S. model while, for self propelled combine harvesters, the R&M cost incidence at 3,000 working hours was 23.1 % as compared with 40.2% calculated through the same U.S. model.

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