hydraulic pumps featured with ultra-pressure, small, safe and efficiency, are widely used in many fields using oil pressure for driving. E.g., with assistance of different fixtures and equipments, it can realize many basic functions such as pushing, stretching, expansion, clamping, bending, lifting, squeezine etc., and it is also well used in many engineering works such as reinforcing steel compression, reinforced concrete for pile driving, pier foundation test etc.