Crane Development origin: history. Rotating mechanism for allowing the boom slewing used 30-ton crane, is supported by the drive unit and the rotary device. Metal structure is the skeleton of a crane, the main carrier such as bridge, boom and mast can be a box-shaped structure or truss structure 30-ton crane, but also for the web structure 30-ton crane sales company, and some can be used as a steel support beam. Crane use and maintenance: Before lifting equipment factory, to make identity records. Installation and maintenance of security checks before: Check equipment performance of the main institutions of integrity, inspection and coupling and its main steel pins, bolts visible defects, corrosion Check the device surface, forming a recording, issued by the installation advice.