... China National Erzhong Group, China National Yizhong Group, Taizhong, Shenzhong, it designed and manufactured on its own 3150t open die hydraulic press. ... such as cross universal coupling, drum coupling, expansion coupling, hydraulic safe coupling, wobbler and star elastic coupling, heavy diaphragm ... and applied for patent in China, and some, such as 35~50 Mpa hydraulic torque wrench, arc face gear ...