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Several aspects must be considered in the design of rolling bearing cages. One of the most important considerations relates to studying and developing a stationary approach for solving problems of heat and mass transfer during convection. In this context, this paper proposes, among other achievements, the development and validation of a model of heat generation that is used, as the basis for an energy-efficient cage design in the context of the roller bearings of axle boxes for rail transport. The forces of interaction of the cage with the bearing parts are determined. The energy-efficient design of the cage is performed with modified friction surfaces in the form of convex contours of the pockets and micro-hollows on the surfaces of the pockets and support rings. On the basis of a flat model, of the interaction between the cage and the bearing parts, the pressure forces on the driving and driven rolling elements in the zone of radial loading are determined. The frictional moment of the bearing has been determined based on the integral design of the cage without taking into account lubrication during the interaction of the cage with the jumpers and with the sides of the basing ring. The calculation of the temperature gradient with standard and improved designs of bearing cages has been performed while taking air blowing into account; results showed a decrease in the average level and growth rate of the bearings’ temperature gradient with an energy-efficient cage design. Based on the obtained results, and on the developed heat generation model, a systematic approach for energy-efficient design of rolling bearing cages is proposed. The proposed approach, as well as the respective developed models, were validated by obtaining and analyzing the experimental results.

Problem. This article highlights the current state of diagnostics of gears on the level of accumulated fatigue damage in operation. The generalization of the known information on determination of a technical condition of separate gear wheels, especially with big modules (m> 20 mm), allows to outline prospects of development of such diagnostics of a technical condition of gear wheels directly in the course of operation. Goal. The goal of this study is to develop an algorithm for diagnosing the technical condition and forecasting a fault-free operation of the gears of heavy-duty machines. Methodology. The least squares method and the confidence interval method are used to predict accident-free guaranteed gear operation. Results. A procedure for diagnosing the technical condition of gears by measuring the hardness of the metal has been developed, which includes five main stages: selection of the device; choice of measurement scheme; selection of the number of measurements, number and relative position of measuring points; development of a design of a template for measurements; development of a device for fastening templates. When determining the accident-free guaranteed operating time on the basis of several criteria of the limit state, the final decision is made on the criterion that determines the minimum term. Originality. The method of forecasting accident-free guaranteed operating time of gears is chosen taking into account the stages of running-in and stable in linear function accumulation of damage in operation. Practical value. The use of the developed procedure for diagnosing the technical condition of the gears of gearboxes of heavy-duty machines will significantly increase the efficiency of their operation due to the transition from scheduled preventive maintenance to maintenance according to the actual technical condition.

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