Due to the particularity of the structure of the excavator and the diversity of the on-site conditions, it is easy to cause failure of the rotary bearing, rotary ring gear or rotary motor due to oil leakage. Therefore, leakage should be prevented and dealt with in a timely manner. This article will introduce some maintenance methods summarized from practice.
Slewing bearing structure and lubrication principle
In fact, the grease lubrication of the rotary part of the excavator is divided into two chambers: the rotary bearing lubrication chamber and the rotary ring gear lubrication chamber.
Slewing bearing lubrication is accomplished through the lubrication nozzle located on the outer ring of the slewing bearing. Lubricating grease is added to the slewing bearing. The slewing ring gear is lubricated by the pre-added grease. The slewing bearing has two inner and outer (or up and down) rubber strips as oil seals. The outer oil seal is fixed to the inner ring (fixing plate) of the slewing bearing of the lower frame to prevent dust and debris from entering the slewing bearing. The inner oil seal is located on the outer ring (movable plate) of the bearing to prevent the grease in the rotating ring gear from entering the bearing. The same brand of grease is used for the slewing ring gear and the slewing bearing.
The rotary oil seal gradually becomes thinner and gradually forms a sharp corner. Only the elasticity of the rubber itself presses the end face of the rotary bearing against the deformation of the rubber to achieve the sealing effect. This kind of seal has a slight effect on preventing grease leakage, but the pressure bearing is not high. Once the pressure is increased due to too much oil or the working temperature increases, the grease will still leak through the oil seal. Under normal circumstances, the amount of leakage is related to many factors such as the amount of filling, the working speed and frequency of the rotating part, and the on-site temperature. Therefore, there is ambiguity between normal and abnormal leakage.
