The slewing bearing is responsible for the operation and rotation of marine equipment, engineering machinery, light industry machinery, metallurgical machinery, medical machinery, and industrial machinery and equipment. It is an important transmission component necessary for machinery that needs to bear axial force, radial force, and tipping moment. . Therefore, the consideration of performance guarantee in the structural design of the slewing bearing cannot be said to be insufficient.
The rotating structure needs sufficient lubrication, and the slewing bearing is no exception. The grease lubrication of the rotating part of the bearing is divided into two cavities: the slewing bearing lubrication cavity and the rotating gear ring lubricating cavity. The lubrication of the slewing bearing is completed by adding lubricating grease to the lubricating nipple located in the outer ring of the slewing bearing, and the lubrication of the slewing ring gear is completed by pre-filled grease. The slewing bearing has two rubber strips inside and outside (or upper and lower) as oil seals. The outer oil seal is fixed on the inner ring (fixed plate) of the slewing bearing of the lower frame to prevent dust from entering the slewing bearing. The inner oil seal is located on the outer ring (moving disc) of the bearing to prevent grease in the rotary gear ring from entering the bearing.
However, equipment and related accessories will be affected by a variety of comprehensive factors in actual use, and abnormal phenomena are inevitable. The oil leakage of turntable bearings is one of the common failure phenomena.
Generally, it is normal for a small amount of oil leakage in the outer oil seal under working conditions. The so-called normal means that the amount of grease leaking through the outer seal of the slewing bearing is approximately equal to the amount of grease added to the slewing bearing. However, when an abnormal phenomenon of a large amount of grease leakage occurs on the excavator, it should be checked. Due to the particularity of the lubrication structure of the rotating part, it is necessary to analyze whether there is a leakage and determine the problem in order to solve the problem.
Since the grease filled in the original equipment may be incorrect, the grease will become thinner when the temperature of the slewing bearing or the slewing ring gear rises slightly. If the thinned grease is pushed to the upper section of the ring gear during the meshing process by the driving gear of the rotary motor, it will flow into the bearing cavity through the inner oil seal, and the grease will drip out from the outer oil seal.