Constructive improvement of mobile energy means, in particular their main unit - the internal combustion engine, is directed on: maintenance of differentiation of size of parameters of functioning of mechanisms of systems depending on variability of conditions and modes of operation of cars; increase of technical resource at use of cars on purpose in the set operating conditions. The existing methods and tools for diagnosing vehicle engines do not fully determine their current technical condition, which requires the development of mathematical models to automate the process of diagnosing their components and parts was found іn the analysis of literature sources. The object of diagnosis is a diesel internal combustion engine of the YaMZ-238 family, which is part of the power unit of most vehicles. Mathematical model of automation of the process of diagnosing internal combustion engines of the YaMZ-238 family is presents in the article. Replacing real technical devices with their idealized models allows the widespread use of various mathematical methods. In this case, the internal combustion engine of the YaMZ-238 family, as the object of diagnosis, is presented in the form of a «black box», the input and output parameters of which have a finite set of values. In general, the mathematical model is a system of functional relationships between each diagnostic signal and structural parameters. For internal combustion engines of the YaMZ-238 family, a diagnostic matrix has been compiled, which includes a list of faults and signs of faults. It is determined that the process of diagnosis based on the model of the diagnostic object is possible if the inverse transformation of the number of signs of malfunctions into the number of structural parameters (malfunctions) of the object was unambiguous. The proposed mathematical model of automation of the process of diagnosing internal combustion engines of the family YaMZ-238 will detect faults of components and parts depending on their characteristics.

The machine-tractor fleet of enterprises is an important link in the production of products of various branches of industry in Ukraine. The timely performance of transport, agricultural, road construction and other works, and ultimately the cost of products or services, largely depend on its effective work. Rolling bearings are one of the most common technical devices used in machines. They largely determine the reliability and performance of devices. The resource of the tractor chassis is mainly determined by the resource of the rolling bearings. Defects in the manufacture and operation of bearings affect the vibration signal in different ways and have different diagnostic signs. This makes it possible to identify defects at the stage of their occurrence and predict further development. In this work, the method of vibrational non-destructive testing is considered when diagnosing the bearing assemblies of the hubs of steered axles of wheeled tractors of traction class 1.4. The mathematical model developed by the authors for diagnosing the bearing units of the hubs of steered axles of traction class 1.4 wheeled tractors is aimed at determining the technical condition of the rolling bearings and allows predicting their possible service life. The developed mathematical model allows you to determine the clearances in the bearings, vibration frequencies and the average value of deformation caused by the load on the bearing depending on the frequency of rotation of the separator and the inner ring of the bearing, the initial contact angle of the rollers in the bearing, the radius of the seat of the roller, the inner diameter of the bearing, the radius of curvature of the bearing. An equation was created to determine the unbalance of the hub of the steered axles and the seating clearance of the bearings.

The main reason that restrains the development of seed production of perennial grasses is losses during harvesting, which depend on the agrotechnical properties of plants and the imperfection of existing means. There are no special grass seeds yet. Therefore, serial equipment with special devices is recommended for their collection. There are enough options for technologies for collecting grass seeds. In the article, six main options of technologies used in production were analyzed and compared according to the main indicators. The best results of a comprehensive comparison are those technologies that process the collected seed mass into a stationary one. The design of a device for wiping the seed mass was proposed to develop this direction of grass seed collection technologies. The article presents theoretical and experimental research results that allowed improving these devices based on rational design and operating parameters. Another way to intensify the production process of leguminous grass seeds is to combine the technological processes of wiping and separation in one machine. The analysis of various separating devices showed that machines with a rotating screen of cylindrical or conical shape are best suited for this purpose. The conducted theoretical studies confirmed the hypothesis that extending the time the material stays on the sieve by using a conical surface increases the yield of clean seeds and contributes to uniform loading of the sieve surface, improving the quality of the initial material. According to the research results, the design of the grating-separating block was proposed for the implementation of this scientific hypothesis. The theoretical and experimental studies presented in the article will allow for significantly intensifying the process of collecting grass seeds and outlining the further development of scientific research in this field.

When designing a car, designers must find a compromise between the dynamism and economy of the car, on the one hand, and reliability and safety - on the other. The first problem is solved mainly by reducing the weight of the car by optimizing the design and reducing strength reserves, and the second - by increasing the strength and durability of structural elements. Reliability of units of cars is the maximum at work on steady modes that confirms experience of their operation. It is known that in the conditions of country routes on good roads reliability of cars is essentially higher, than at operation within the city. In cities, unstable modes of operation of car units are caused, first of all, by frequent stops and subsequent accelerations due to the presence of traffic lights, pedestrian crossings, railway crossings, traffic jams, steep ascents and descents on car routes, etc. All this necessitates frequent braking, shifting gears and moving. These circumstances lead to an increase in the dynamic load of the vehicle units and, as a consequence, to the intensification of the processes of wear of the friction pairs of the clutch discs, gears and cardan gears, and so on. All the factors that reduce the reliability of car units in urban conditions are particularly evident in the example of buses and taxis with a manual transmission. According to some data, the share of failures of mechanical transmission units of such cars is 19 ... 23% of all failures. During intensive operation of the car, various clutch malfunctions can occur. There are malfunctions of the actual clutch and malfunction of the clutch drive. Coupling defects occur not only due to intensive operation, but also due to violations of operating rules. Currently, clutch failures are mainly diagnosed by external signs. However, one external feature may correspond to several clutch failures. Thus, the process of determining the technical condition of the clutch of vehicles is an urgent scientific and technical task. A mathematical model of the clutch of the Volkswagen Polo Sedan as an object of diagnosis are presents in the article. A matrix for diagnosing the clutch of a Volkswagen Polo Sedan and a block diagram of its synthesis have been built.

In the theory and practice of road haulage there are many different types of transport systems, which differ significantly from each other. Urban freight transport is usually performed by one or more vehicles on pendulum or ring routes, i.e., are a small transport system. In such transport systems there is an uneven operation of vehicles, which is the value of the deviation of production in tons and tonne-kilometers, which occurs daily depending on the influence of many factors. The most significant factors that cause uneven operation of vehicles are the inconsistency of the average technical speed of cars and their downtime under load-unloading.Uneven operation of cars significantly affects their implementation of the transportation plan, and thus leads to a decrease in productivity and profits of the trucking company. At the same time, a review of previously performed scientific papers showed that the issues of taking into account the unevenness of cars in operational planning were not given enough attention.The article proposes to consider the average technical speed and downtime under load-unloading not as determined, but as random variables, the distribution of which is consistent with the normal law. Accordingly, a mathematical apparatus is proposed, which allows to model the operation of a small transport system taking into account the uneven operation of vehicles. Taking into account the probabilistic nature of these values allows to increase the accuracy of modeling the operation of a small transport system and the possible occurrence of queues for loading or unloading in cargo terminals. Based on the use of this mathematical model, the paper improves the methodology of operational planning of urban freight. The use of the proposed technique will reduce downtime of cars and increase the efficiency of the transport company.