Crane Development origin: history. Early 20th Century 25 t crane manufacturers in Europe began using the tower crane. Crane hoisting mechanism mainly run institutions, luffing mechanism, slewing mechanism and metal structure. Hoisting mechanism is the basic working body of the crane, mostly by hanging system and winch composition, but also lift weights through the hydraulic system. Crane Development origin: history. Boom slewing mechanism for causing rotation is determined by the drive means and the rotary bearing device. Metal structure is the skeleton of a crane 25 tons crane manufacturers, the main carrier such as bridge, boom and mast can be a box-shaped structure or truss structure, but also for the web structure, and some can be used as a steel support beam.