DETERMINATION OF CONTACT STRESSES AND GAPS IN CHAIN TRANSMISSION HINGES

The article considers the questions of determination of contact stresses in the chain transmission hinges that need to be known for assessing their wear resistance, because the wear and tear of hinges is the most common type of damage to the chain gears. In this context the main attention was paid to determining the required clearance between the bushing and the pin of roller chain drives. This gap largely determines the character of the distribution and magnitude of contact stresses in the hinge, and, consequently, the durability of chain drives. A method of calculation of the maximum contact stresses in the chain transmission hinges is developed. It is shown that decreasing clearance in the hinges increases the contact angle between the pin and the bushing and reduces the maximum contact pressure. However, for the actual angles of contact the contact stress greatly exceeds the allowable average unit pressure, causing increased wear of the hinges. One of the possible solutions to this problem is the use of transition fits in hinges, in which the gaps and interferences are relatively small. When pressing the pins into in the bushings, due to cutting microasperities from the contact surfaces, the interference in the connection virtually disappears. Examples of determining gaps and contact stresses in the chain transmission hinges are provided.