Since the reform and opening up, and actively introduce, digest and absorb foreign advanced technology, domestic second-hand digging machine information to promote the development of China excavator industry. Wherein Guiyang mining machinery plant, construction machinery plant Shanghai, Hefei mining machinery plant, the Yangtze River were the introduction of the German excavator factory Liebherr (Liebherr) Hydraulic Mining Company A912.R912.R942.A922.R922.R962.R972.R982 manufacturing technology. A few years later, the introduction of Germany Demark Hangzhou Heavy Machinery (Demag) the company's H55 and H85 hydraulic excavator manufacturing technology, domestic second-hand digging machines, construction machinery plant in Beijing to introduce German Aojia Kai (0 & K) and the company's RH6 MH6 hydraulic excavator manufacturing technology. Further improvement of the hydraulic system. , The hydraulic system has a small hydraulic excavators clear trend towards variable system change. Because the variable pump system in operation, with increasing domestic second-hand digging machine recovery, pressure compensated flow decreases, domestic second-hand excavator market, the hydraulic pump power remains constant, that is equipped with a variable displacement pump hydraulic excavator regularly take advantage of the maximum pump power. When the external resistance increases decreased flow (reduce speed), so digging force multiplied; three-circuit hydraulic system. Domestic second-hand digging machine recovery, Jin Hao used excavators, domestic second-hand digging machine provided 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.