## 2 Literature Review: Methods Used in the Spare Parts Supply System  
The reliability of vehicles depends not only on the quality of the vehicle design, but also on its further service support. To keep the vehicle in working condition, timely maintenance of its systems and mechanisms is necessary. In this sense, high-quality and timely provision of spare parts is one of the key links in this process. To ensure that service needs are met in the shortest possible time, a certain level of spare parts is kept in stock. The authors of [4] propose the use of a centralized control strategy. Based on centralized real-time storage of spare parts demand information in each region, centralized inventory control in each sub-warehouse is carried out by the coordinating center. The demand for spare parts depends not only on the planning of spare parts for vehicle maintenance, but also on the possible failures of the vehicle's systems. The failure of their parts, components, and assemblies is probabilistic in nature, this can happen at any time, while the desired part may not be in stock. Therefore, automotive companies are developing their own inventory forecasting methods that will take into account various factors that affect the operational state of vehicles. For automotive companies, it is very important that the level of customer satisfaction of auto repair shops meet their expectations, while not increasing the cost of holding inventory. Demand for spare parts is not stable. Seasonal changes also affect the formation of stocks [5]. The number of heavy trucks in Russia at the beginning of 2023 amounted to 2.483 million units. The share of vehicles older than 10 years is about 69%, and KAMAZ trucks older than 10 years is 60.8%, which is lower than the national average. Experts noted that truck drivers are involved in traffic accidents 1.7 times more often than other road users. Thus, at the end of 2021, the frequency of insured events in the category of trucks was 8.3%, which is 3.2% higher than the average number [6]. All this leads to a higher failure rate. In [7],the number of spare parts is determined by the number of accidents, and the number of accidents is determined by the total number of vehicles sold. Most service centers use a warehouse management system based on event forecasting, and it is relevant with an ideal logistics system and a minimum time factor. If these criteria cannot be met, maintenance and repair times are extended, especially away from logistics centers [8]. In [9], the authors propose a methodology that allows us to determine the required range and quantity of spare parts for a known fleet of vehicles with a given load and conditions for ensuring the calculated level of reliability and performance of equipment. The algorithms and mathematical apparatus presented in the article make it possible to determine the range of spare parts depending on the operating time parameters of special vehicles and their failure rate [10]. Many studies use the ABC classification method, that is, the division of spare parts into groups [11; 12]. When repairing vehicles, spare parts are the main part. In [13], the authors studied the number of vehicles sold and their mileage associated with each of the spare parts and used rough set theory based on ABC analysis. In the article, solving the problem of the diversity of spare parts and their distribution, the ABC classification method for automotive parts based on DEA was built [14]. Various mathematical methods are used to determine the required stock, from the simplest to the most complex. Inventory formation involves maintaining such a ratio of parts with frequent or irregular demand so that there is a high turnover at the same time, so that the costs of maintaining inventory are most favorable.