V-belt transmissions of agricultural machines

Abstract

The article is devoted to the analysis of design features and operating conditions of V-belt trans-missions of agricultural machinery. When designing these gears, it is recommended to give prefer-ence to gears made according to an open circuit or with a tension roller located outside the belt con-tour, to avoid cross and semi-cross gears, as well as multi-pulley gears with crossing shaft axles. To make the wider use of more progressive types of belts. It was shown that the features of V-belt transmissions of agricultural machinery require clarification of the methods for calculating trans-missions with progressive types of V-belts and automatic belt tensioning methods. It was noted that special attention should be paid to transmissions with multi-profile belts, which calculation has not been sufficiently reflected in domestic regulatory documents. The advantages of such belts are es-pecially noticeable under variable and shock loading. Based on the analysis, the recommendations for clarifying the calculation of belt drives with multi-profile belts were given. Analytical dependencies are proposed for determining the value of the nominal power transmitted by one belt (stream) of a multi-profile belt, allowing automation of the calculation of V-belt transmissions of agricultural machinery. For gears with a tension or guide roller that add an extra (sometimes reverse) bend of the belt, it is proposed to determine the coeffi-cient taking into account different degrees of bending on the pulleys according to a graph built tak-ing into account the linear hypothesis of summation of damages. It is recommended to calculate gears with spring-loaded tensioning rollers and design tensioning devices for such transmissions using a special method that takes into account the belt tensioning method. At the same time, the required value of the pre-tension of the belt can be significantly re-duced, which will have a positive effect on its resource, without losing the traction capacity of the transmission itself. Expressions are given for finding the value of the pre-tension of belts, both for gears with tension due to the elasticity of the belt, and for gears with spring-loaded tension rollers. Conclusions and directions for further research are formulated.