Relation of execution time and rock mass physical and mechanical parameters during executing horizontal developments in the lead and zinc mines
The task of this paper was to determine technical characteristics of the combined machine working part, based on the calculations and working experiences, which could be applicated for the development works in the working conditions – coal, in the domestic underground coal mines. Laboratory data for specific working conditions are used, and calculations of necessary power of the electrical engine with driving working part, are realised by the determined methodology. Framework of the working tool characteristics (for the working enviroment – coal) are given by the analysis of the received data, which include number of rotation of the driving electrical engine, number of knives, and necessary power of the driving electrical engine. 
