The article contains the research findings on the justification of kinematic and power parameters of a rack and pinion system for heavy-loaded mining machines. The article points out that for a designer to find more reasonable constructive solutions it is advisable to carry out wear assessment of the designed gear at a design stage. Application of additional quality parameters of gearing is proposed, i.e. coefficients of acceleration and sliding velocity and the scoring resistance coefficient. Introduction of these parameters will allow choosing geometrical parameters of the designed gearing, which will possess the best kinematic and power character-istics and will be least inclined to wear.