Tower crane originated in Western Europe.  A rotating crane with a boom mounted on the upper part of a towering tower.  It has a large working space and is mainly used for vertical and horizontal transportation of materials and installation of building components in house construction.  It consists of three parts: metal structure, working mechanism and electrical system.  The metal structure includes the tower body, boom and base.  The working mechanism has four parts: lifting, luffing, turning and walking.  The electrical system includes motors, controllers, distribution cabinets, connecting lines, signals and lighting devices, etc.From the perspective of the technical development of tower cranes, although new products are emerging one after another, and the new products have improved in terms of production efficiency, ease of operation, ease of maintenance and reliable operation, the technology of tower cranes has not fundamentally changed.  Research on tower cranes is moving towards combined development.  The so-called combined type is to take the tower body structure as the core, decompose the tower body into several parts according to the structural and functional characteristics, and then divide each part into several modules according to the serialization and generalization requirements and the modular system principle.