Update the design theory, improve reliability, professional second-hand digging machinery, and prolong life. United States, Britain, Japan and other countries to promote the use of finite life design theory as an alternative to the traditional infinite life design theory and methods used digging machine digging machine factory and fatigue damage accumulation theory, fracture mechanics, finite element method, optimization design, electronics computer-controlled electro-hydraulic servo fatigue testing technology, the fatigue strength analysis method and other advanced technology to strength research hydraulic excavator, digging factory used to promote the efficiency and competitiveness of high quality products. Derailer wear on W4-60 excavator uses a mechanical shift as the transmission mechanism, which relies on a sliding gear transmission mechanism sets a fixed gear sleeve to move axially and engages with the gear to the driven gear realize shifting. In the frequent shifting process, each gear tooth end surface of the cone of ground easily, resulting in lower performance and cause its engagement 'skip-shift'. Used excavator digging Factory, Kim Ho used excavators (certified), used to dig Factory by Shanghai Used Construction Machinery Co., Ltd. Jin Hao. Shanghai Jin Hao Used Construction Machinery Co. (www.jinhaosh.cn) is the Shanghai Minhang District, mining machinery leaders, over the years, the company is implementing the scientific management, innovation and development, the principle of honesty and trustworthiness, and satisfy customer needs. Kim Ho used excavators in leadership with the staff warmly welcome all inquiries negotiations to create jinhao used excavators better future.