Given the critically important role of haul trucks in the overall mineral extraction process chain, the suspension system — the component with the highest failure frequency — was selected as the research object. The authors propose a method for quantitatively assessing a group of parameters of a technological transportation route due to challenging mining operating conditions. Using data from two mining enterprises over a three-year period, dependence was established between the reduction in the service life of dump truck suspensions and each of the identified factors in the route parameter groups. The assessment was carried out using data from remote monitoring systems installed on the vehicles. Based on the derived dependence, a criterion for optimizing the overhaul interval of haul truck suspensions was developed, incorporating a set of planning and economic factors. This criterion allows decisions to be made on the advisability of implementing measures aimed at achieving a target reliability level for the suspension system within the framework of the maintenance strategy adopted by mining enterprises, which combines scheduled and emergency repairs of machine components and assemblies. Using the proposed criterion, an optimal ratio between grading equipment and haulage equipment was determined when forming the vehicle fleet. Furthermore, an algorithm for determining a rational overhaul interval for haul truck suspensions was developed based on this criterion. Implementation of the algorithm at the mining enterprises under study has significantly reduced both the duration of unplanned downtime caused by suspension failures and the time required for repair activities.

The necessary condition for the operation of crushers in the production of crushed granite is feeding of the crushers with granite fragments of a certain size. At the same time, granite fragmentation after blasting does not always meet the required size for the crushers and needs additional destruction by blasting or disintegration directly on site. Hydraulic breakers are most often used in disintegration of oversizes. For example, in quarries in Vietnam, JCB HM380 hydraulic breakers with a fracture energy of up to 2.5 kJ are widely used. The working tools of the hydraulic breakers are steel picks of various diameters and shapes. The operation of this tool is accompanied by its intensive wear due to the impact-abrasive action of rocks; the pointed part of the tool gets gradually blunted, which affects the rate of penetration of the pick in rock. In this regard, it is relevant to determine the influence exerted by the degree of wear of the pick on the performance of the hydraulic breaker, and to find out whether replacement or re-sharpening of the pick is expedient. In this paper, based on the previously determined crack propagation velocity in granite and the impact time, the length of the fracture is calculated. The dimensions of a crack in a granite block are calculated depending on the degree of blunting of the pick at a certain number of blows per cycle. At the same time, the limiting value of a crack that causes chipping of a piece from rock mass was considered as the fracture length to free surface at different degrees of pick blunting. Based on these calculations, the average productivity and energy input of disintegration process were determined. It is shown that for a tool with a completely worn tip, the decrease in the productivity and the increase in the energy input of fracture reach two times compared with a sharpened pick. In this regard, from the point of view of increasing the hydraulic breaker capacity, it is advisable to replace or re-sharpen the pick after complete wear of its tip.

The article was devoted to the study of an automated electric drive with a scalar closed-loop speed control system. Severe duty and operating modes of electric drive determine the actual service life. Wear of the induction motor, as a key link of the electric drive, was associated with deviation from nominal parameters. The deviation of parameters of the induction motor equivalent circuit determined the resultant change of characteristics. The parameters of the equivalent circuit determined the accuracy of the adjustment of regulators and optimal algorithms in the control system of the electric drive. In continuous operation modes the possibility of auto-tuning regulators, which requires stopping or no-load mode, was excluded. The paper considered the influence of the magnetization circuit mutual inductance value of the induction motor on the behavior of the electric drive control system. Evaluation of the behavior of the scalar closed-loop speed control system was performed on the basic energy (power factor, efficiency factor) and mechanical (speed, electromagnetic torque) characteristics of the electric drive.