EFFECT OF RESISTANCE TO ROLLING ON THE DYNAMICS OF THE LIFTING MECHANISMS OF THE TRANSPORTING MAC

Purpose. Coefficient of rolling friction in bearings determines the amount of resistance to rotation of rope drums of the lifting mechanisms of transporting machines, which affects the value of the efficiency of such machines and their dynamics accordingly. To clarify the values of the efficiency and the speed of cargo, it is necessary to determine analytically the amount of rolling friction coefficient for the ball bearings of the lifting mechanism drum, reduced to a pin, and also to evaluate its influence on the dynamics of such a mechanism. Methodology. In the paper, dependences are given for determining the coefficient of resistance of the ball bearing of the cable drum of the lifting mechanism when it is rotated by both the inner and outer cages, as well as the design schemes of the bearing and drum. Findings. According to the results of research the dependences for definition of cargo movement speed and efficiency of the lifting mechanism of transporting cars with the specified value of movement resistance coefficient are presented. The corresponding graphical dependencies for a concrete example are constructed. Analysis of the obtained dependencies and graphs allows us to draw the following conclusions: 1) the rate of lowering the load depends on the position of the rope along the length of the drum, decreasing as it approaches its middle; 2) the coefficient of friction of the bearings of the drum reduced to the pin increases as the rope approaches the middle of the drum; 3) the efficiency of the rope drum depends on the position of the rope on the drum, decreasing as the rope approaches the middle of the drum; 4) the efficiency of the bearing depends on whether the holder rotates: internal or external, and the difference depends on both the load on the bearing and the lubricant, reaching more than 3% in its absence and 2% - with liquid lubrication. Originality. The authors obtained more accurate dependences of the lifting speed of the load and the efficiency of the lifting mechanisms, using, in this case, the dependences determined by the drag coefficient in the drum bearings. Practical value. The obtained values of resistances can be used for refined calculations of the lifting mechanisms of transporting machines