Estimation of repair and maintenance cost of a tractor base on HP and working hours: Case study of Sudan

A field survey was carried out in Gezira Scheme, Blue Nile State and North Kordofan State, to collect the data for tractor repair and maintenance costs, and annual hours of use of four selected models of Farmtract type tractors farmtrac80 (FT80), farmtrac70 (FT70), farmtrac60(FT60) and powertrac55 (PT55). The results showed significant (P> 0.05) differences between repair and maintenance costs in different systems of tractors. The lowest cost was recorded in the electrical system of the tractor FT 80, while the highest cost was recorded for the engine. For the tractor (PT55) the lowest cost was recorded in the hydraulic system and the highest cost was recorded in transmission system. Different mathematical regression models were also developed for accumulated repair and maintenance cost prediction such as linear, polynomial, exponential, logarithmic and power. The power model was created. The derived models indicated that the accumulated repair and maintenance costs as percentage of initial purchase price was increased as the accumulated hours of use increased for the four selected tractor models and the mean model derived.