The empirical-analytic model of milling in a ring-ball mill has been presented. It concerns the interaction of the basic design features of the grinding unit (geometry, rate of grinding and thrust of the balls) on the maximum efficiency of the mill. The production of pulverized coal was expressed by the product of the flux of material drawn in by the balls and the so-called "grinding effect of the balls" (defined by the increase of the mass fraction of dust in its flux). The kinematic quantities (among others, the flux of loose material drawn in by the balls) have been calculated on the basis of a simple analytical description of the flow of particles and some parametrical assumptions. The grinding properties of coal have been determined making use of laboratory tests of its cruising by the rollers. Some verifications of the grinding model on the experimental test stand with a ring-ball mill have been presented. The test stand is installed at the Institute of Power Engineering and Turbomachinery of the Silesian University of Technology.

The paper presents a method for dimensional synthesis of a five-rod guiding mechanism for the front wheels of a car. The goal is to find some unknown coordinates of joint centers of three suspension rods on the basis of given input data describing selected coordinates of other points, rods lengths and desired suspension characteristics for jounce-rebound and steering displacements. The synthesis problem is formulated as a single-criteria optimization procedure with a few substages solved in hierarchical order. The procedures for position and displacement analysis of the spatial multilink mechanism and for determination of the screw axes are also described. A numerical example for the AUDI A4 front ax.le is given.