The slewing mechanism is one of the five working mechanisms of the tower crane, and the slewing support is an important part of the slewing mechanism. This paper mainly analyzes the fault caused by the design, selection, use and maintenance of tower crane slewing support, and gives the solution to reduce the influence of slewing support fault on the use of tower crane, so as to better serve the construction site.
Has a wide of tower crane jib operation, can complete different requirements, in most case, it will have the function of turning, because the rotation of the tower crane is heavy, can reach dozens of tons, even hundreds of tons, not easy to install and maintain, therefore, in order to be able to let the tower crane slewing smoothly and fast, now the tower crane is ball slewing bearing or roller slewing bearing. The slewing support system is an important structural component of tower crane. The slewing support system connects the top and the bottom, the lifting arm, the tower cap and so on. All kinds of loads generated under different working conditions should be transferred to the tower through the slewing support system. As a slewing system, it also bears different loads. The common faults of tower crane slewing bearings mainly include abnormal sound, collapse after raceway corrosion and excessive amount of shaking when the slewing bearings rotate.
1 Failure cause analysis
There are two reasons that affect the normal operation of tower crane slewing bearings. On the other hand is the factory before the assembly and processing, working environment, maintenance. If the design and selection of slewing support is improper, it will affect the performance and safety of tower crane for a long time.
2 Aging effects of rotary bearings
In general, the new slewing support, its ball and raceway precision is in line with the design requirements, the new raceway basically will not appear damage or due to poor quality control of materials and products and raceway damage deformation phenomenon, so the noise described before is not slewing support itself. Rotary bearing is the connection with a group of high strength bolts respectively connected to the upper and lower bearings of slewing mechanism, slewing mechanism and bearing plates welded together, because of welding without the effective heat treatment, machining accuracy deviation, lead to assemble plane error tolerance, the serious influence rotary bearing the overall installation accuracy, easy to deformation, resulting in ball orbit impedance appears on a card, tower crane ball can produce larger resistance through the corresponding position, let the structure by the torque, to produce noise. Generally with the change of time, the ball and raceway run in the average, such imagination will disappear.