The paper addresses issues related to estimation of operational time for open pit excavators during truck loading operations. The author analyzes the method of annual capacity estimation and highlights disagreements in different ways of operational time logging. Recommendations are offered concerning estimation of excavator capacity taking into account its repair cycle. The paper contains an analysis of the cyclical nature of various types of maintenance in the interval between capital repairs as a function of operational time. Guidelines are proposed that allow to calculate annual production days of the excavator with regards to the repair cycle and adjusted utilization coefficient throughout the shift. It has been established that decreasing the coefficient of excavator utilization throughout the shift and more precise logging of annual work days lead to a slower decrease in estimated machine capacity than the one described in the reference literature. According to the suggested method, estimated excavator capacity is more than 23 % higher than the value stated in the reference literature.
