Tower crane plays an important role in the construction machinery industry, and it is also commonly used in people’s daily life which seems irrevocable tendency. The tower crane use a single-row four point contact ball elements slewing ring (01 series) and Double row ball slewing bearing, Dia. of 1000mm-2000mm, 1250mm & 1064mm are both standard.
It is divided into two types for slewing bearing: bottom rotation and top rotation. Top installation is relatively common find in the application; the rest of the structure is installed on the upper part of the slewing bearing except the tower body. The advantage of this installation is that the tower body is fixed and the tower body is fixed. The lower structure is simple and the jacking and adding joints are convenient to operate. The disadvantage is that as the height increases, the center of gravity of the tower crane rising accordingly, which in turn easily effected stability by wind. The advantages of the bottom swing tower crane installation are decrease center of gravity, good stability, and convenient maintenance at a later stage. The disadvantage is that the technical requirements are severe and the installation height is limited.