Repair and Maintenance Cost Models for Mf285 Tractor: A Case Study in Central Region of Iran

Appraisal of repair and maintenance cost models for farm machinery is important to decide for replacement time and to decrease total costs. In this study repair and maintenance costs for MF285 tractor were investigated to present an appropriate mathematical model in order to predict these costs. To present the model, the stratified random sampling method on the basis of tractor age per year was used. The mean accumulated repair and maintenance costs and also the mean working hours (h/year) were calculated for per class separately. Calculated data was analyzed on the five models, linear, logarithmic, polynomial, power and exponential. Finally, it was found that power model gave better cost prediction with higher confidence and less variation than other models.