Causes and repairing methods of slewing rings in construction machinery

The slewing ring is one of the main components of the swing mechanism of construction machinery such as cranes and excavators, it is a component with a high frequency of use in the swing mechanism. Therefore, in various construction machinery, slewing bearings are very easy to failure and damage. What is the cause of the failure of the slewing ring in the construction machinery? How to repair the slewing ring after it fails?

The function of the slewing mechanism is to support the dead weight of the slewing part of the crane and bear vertical force of the lifting load and tilting moment, it is driven by the slewing drive device to make a full circle rotation around the slewing center to lift the heavy objects and and place them in different places. The slewing rings used in construction machinery are generally four point contact ball type and cross cylindrical roller type, large-scale equipment adopts three row cylindrical roller type.

The faults that affect the normal rotation of the truck crane can be divided into mechanical faults and hydraulic system faults. The following engineers of Unique Transmission will give you an analysis of the causes and repair methods of mechanical failures in the slewing rings of truck cranes.

The mechanical failure is mainly the raceway wear formed between balls and slewing ring inner and outer rings. The raceway is composed of semi-circular grooves on slewing ring inner and outer rings. When installing or taking out balls and spacer blocks, all through the special tangential circular hole of the slewing ring inner ring or outer ring, then block this process hole, in use, lubricating oil is often added through grease nipple installed on the raceway circumference.

If the steel ball in the slewing ring is damaged or worn, or the raceway is worn, all will affect normal operation of the slewing mechanism. In severe cases, the rotation of the crane will be blocked, that is rotary heavy, the pressure required to make the rotation exceeds the specified value during design and there is an unharmonious noise.

At this time, when the crane is lifting and unloading, pay attention to observe slewing ring (or put the dial indicator seat on the surface of the lower vehicle, let the dial indicator measuring head touch the underside of the upper vehicle turntable). During lifting and unloading, it will be found that the vertical vibration of the part connecting the upper and lower vehicle is too large, that is the clearance of the slewing ring is too large. In this case, check the slewing ring, if you have the ability to repair the raceway with an enlarged size, you can purchase new balls that have size larger than the original slewing ring balls for installation, it’s more economical to maintain slewing ring. If the wear is particularly serious or cracks are found at the raceway, the slewing ring assembly needs to be updated. In the process of the slewing ring maintenance and installation, the inspection and tightening of the strength bolts should be done in strict accordance with the requirements.