Repair & Maintenance of slewing bearing

• Introduction

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.

• Instruction for maintenance and maintenance of tower crane slewing ring

1. Before the installation, make sure tower crane support to stress relieving to reduce the deformation of the slewing bearing. When installing, the contact surface of the support and the slewing bearing must be cleaned to remove debris and burrs.
2. The grease shall be re-applied to the slewing bearing and the pinion mesh while tower crane continue to work for 8 shift time..
3. In order to ensure the reliability of the bolt work, to avoid the shortage of bolt pre-tightening force, pay attention to check the pre-tightening force of the bolt.
4. Take attention to the change of noise and the change of the rotary resistance torque. If there is any abnormality, it should be immediately shut down for inspection to avoid unnecessary loss.
5. Use high-strength bolts and nuts to connect the slewing ring of the tower crane, cross tightening to keep balance; use double nut to tighten and prevent loosening
6. Before the bolt is fully tightened, the meshing between pinion & gear should be checked. The meshing condition should meet the requirements of the gear precision.