SERVICE LIFE OF THE SUPPORT ROLLERS OF TRACKED TIMBER HARVESTING MACHINES
Due to strict economical factors, determining a service life of the structural components of a tracked timber-harvesting machine (TTHM), including the support rollers becomes a key issue for the manufacturers and customers. With that, optimum relationship between the original cost of the support rollers and their life cycle cost for maintenance and repair during the entire service life shall be observed. The timber harvesting machines are operated under severe environmental and production conditions. In the course of operation, they meet variable obstacle, including stubs, stones, fallen trees, etc., which in their turn affect negatively the service life of the support rollers. This article offers a research of the service life of the tracked timber harvesting machine support rollers. It describes main defects of the support rollers, including operational, mechanical and thermal ones, as well as embedded flaws and dynamic defects. It also presents the factors affecting the support rollers' wear. The article presents a service life-determining model where the following principle can be generally applied. Service life of a support roller is determined by its admissible operational wear-out divided by actual factor for this support roller and operational conditions