Crane manufacturing industry is closely related to urban construction, transportation, energy development and other people's livelihood cause of the industry. In recent years, China's crane industry has achieved rapid development. To bridge gantry crane manufacturing company, for example, to 2008, China's bridge gantry crane has about 450 manufacturing enterprises, employing over 14 million people [1]. If these enterprises are divided into three echelons: big play, too heavy in the first echelon, they are the industry's largest economy enterprises, with national technical center, comprehensive strength, in order to produce high-end products, such as nuclear ring cranes, large weight metallurgical cranes, foundry cranes, large dock cranes, etc.; second tier that includes Weihua Group, including China's top 20 companies, most of them have plant-level technology center, which is the establishment of Weihua Group regional technology center in Shanghai set up a product design and Research Institute, these enterprises are the backbone of the industry, products cover a wide range of high-end products both in bidding, also participated in the competition from cheap generic products; third echelon is the remaining four hundred SMEs, which generally are small, roughly the same product type, and to be priced competitively based market share effective strategies to enable these enterprises generally poor, severely Hand stacker the pace of development. Then, in the vagaries of the market today, a large number of third-tier companies, the fate of which way to go?Check the overhead crane and even the loose coupling "scroll keys." Focused on checking flexible pin coupling elastic rubber ring without abnormal wear on tooth gear coupling ring to pay special attention to its wear condition. Poor accuracy due to the installation, the two large offset between the shaft case, the performance of the entire ring will soon wear short bald. If the lifting mechanism in such a case, prone to serious accidents.