How does over-greasing the slew ring impact its longevity?

Over-greasing the slew ring, while seemingly beneficial, can negatively impact its longevity by causing seal damage and attracting contaminants. The slew ring, or swing bearing, is a large bearing that allows the excavator's upper structure to rotate smoothly. It requires regular greasing to maintain proper lubrication and reduce friction between the rolling elements (balls or rollers) and the raceways. However, excessive grease can over-pressurize the seals that retain the grease within the bearing. These seals are designed to keep grease in and contaminants out, but they have a limited pressure capacity. Over-greasing can force grease past the seals, damaging them or even causing them to rupture. Damaged seals lose their ability to effectively retain grease, leading to grease leakage and reduced lubrication. This also allows contaminants, such as dirt, dust, and moisture, to enter the bearing. These contaminants act as abrasives, accelerating wear and reducing the bearing's lifespan. In addition, over-greasing can create excessive heat buildup within the slew ring. The excess grease increases the internal friction, generating more heat during rotation. This can lead to premature grease breakdown and further reduce the bearing's lubrication effectiveness. Some slew ring designs also have grease relief valves or vents to prevent over-pressurization. However, these relief valves can become clogged or malfunction, leading to the same problems as over-greasing without a relief system. Following the manufacturer's recommended greasing intervals and grease quantity is crucial for maintaining optimal slew ring lubrication and preventing premature failure. It's better to grease frequently with the correct amount than to infrequently apply excessive grease.