Cracks Cause excavator boom side cracks reasons: including the original weld itself bubbles, slag, and minute cracks when the excavator overworked, small second-hand excavator factory, will produce original weld microcracks and slowly expand: when welding electrode and the plate does not match the performance and cracks: a large excavator boom due to volume, Tianjin second hand excavators, difficult to employ reliable and effective heat insulation measures, has not been completely removed after welding welding seam hardened area surrounding the base metal, the small second-hand excavator market, resulting weld strength decreases: excavators greater impact vibration during operation, so that the weld seam at the uneven stress cracking. The second generation excavator: With the widespread use of hydraulic technology, the excavator has been applied more scientific gear, hydraulic excavator instead of mechanical drive technology is a major leap forward. 1950 Germany's first hydraulic excavator was born. Mechanical drive is the second generation of hydraulic excavators. Small second-hand excavator net, Jin Hao used excavators, used mini excavators Tianjin Jin Hao from Shanghai Used Construction Machinery Co. 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.