Influence of car’s crankshaft–clutch assembly repair on the magnitude of their imbalance.
Students Name: Dets Stanislav Tarasovych
Qualification Level: magister
Speciality: Motor Vehicle Transport
Institute: Institute of Mechanical Engineering and Transport
Mode of Study: full
Academic Year: 2025-2026 н.р.
Language of Defence: ukrainian
Abstract: Vibrations that occur during the operation of machines and mechanisms entail increased loads on parts, which cause intensive processes of their wear and tear and reduce the durability of products, and also negatively affect the physiological state of a person. Most of them are caused by the imbalance of their components. Therefore, to reduce this negative phenomenon, balancing of rotating bodies of machines is carried out by changing their mass during repair or maintenance work. Experience in operating motor vehicles (MVs) [1, 2] shows that balancing their parts and assemblies increases their durability by 25-100%, and in relation to engines increases the useful power by 10%.. The object of the study is is the imbalance of the crankshaft coupling with the flywheel and clutch. The subject of the study is the distribution curves of the imbalance indicators of the crankshaft coupling with the flywheel and clutch during the technological process of repair. The purpose of the work is to calculate the probabilistic characteristics of the unbalance of the crankshaft-flywheel and clutch coupling during their repair. The first section describes the essence of the balancing process and outlines the types and schematic diagrams of unbalance of machine parts and assemblies, which can be static, dynamic or mixed. Formulas are given for determining the centrifugal force that causes dynamic unbalance and the moments it causes. Balancing methods and devices and equipment used for this are considered [3]. The classification of equipment for static and dynamic balancing of parts is given, as well as the requirements for it are formulated. In section 2, the unbalance of parts and assemblies of MVs is analyzed, and the permissible imbalance values of some of them are given. Specialized machines for balancing crankshafts and cardan shafts, as well as automobile wheels, are described. Design and schematic diagrams are illustrated and methods of working with them are considered. Section 3 is devoted to the quantitative assessment of the unbalance of the restored crankshaft in the assembly with the flywheel and clutch. To assess the influence of technological variables on engine vibration, the results of experimental studies were used, in which a number of factors and their interaction with the overall engine vibration were considered. It was found that the balance is affected by many elements, and the most important among them is the mismatch of the crankshaft to the flywheel and the clutch assembly. The experimentally obtained distributions of the crankshaft unbalance were agreed with the theoretical ones using the normal law [4]. Variations of the random variable, detected using statistical analysis, allow us to assess the reliability of the above-mentioned indicator. The results of the research show that the imbalance exceeds the permissible norm (70 g cm) both during operation and during overhaul, reaching values up to 800 g·cm. It is worth noting that the clutch imbalance is within 350…750 g·cm. This indicates that the clutch imbalance is the main cause of the imbalance of the unit as a whole. Therefore, during repair or replacement of the clutch, it is necessary to balance it, taking into account that the crankshaft in the unit with the flywheel is balanced. Moreover, during overhaul, before balancing the crankshaft together with the flywheel and clutch, the imbalance fluctuates within 50…2100 g·cm. Keywords: imbalance, balancing, crankshaft, flywheel, clutch, empirical studies, probabilistic model.. List of used literary sources 1. Anilovych V. A. Mitsnist ta nadiinist mashyn / V. A. Anilovych.- K.: Urozhai, 1996.- 288 s. 2. Fornalchyk Ye. Yu. Tekhnichna ekspluatatsiia ta nadiinist avtomobiliv: navchalnyi posibnyk / Ye. Yu. Fornalchyk, M. S. Oliskevych ta in.- Lviv: Afisha, 2004.- 492 s. 3. Polianskyi O. S. Tekhnolohiia vidnovlennia detalei ta remontu avtomobiliv: navchalnyi posibnyk / O. S. Polianskyi, B. V. Savchenkov, Ye. O. Dubinin ta in..- Kharkiv: vyd-vo KhNADU, 2012.- 312 s. 4. Drahomyretska Kh. T. Teoriia ymovirnostei ta matematychna statystyka: navch. posibnyk / Kh. T. Drahomyretska, O. M. Rybytska ta in..- Lviv: vyd-vo NU «Lvivska politekhnika». 2012.- 396 s.