Effect of Contact Conditions on Oil Leakage in Floating Seals

Floating seals, commonly utilized in shaft seals, such as those found in crawler tracks for construction equipment, are composed of a pair of metal seal rings and rubber O-rings. During operation, the O-rings move to relieve load distribution, causing the seal rings to also move, resulting in complex changes in the contact conditions of the sealing surfaces. In this study, the relationship between the contact conditions between the seal rings and the occurrence of oil leakage in the case of eccentricity between the seal rings was investigated through experiments and analyses. The results confirm that if the eccentricity is small, a surface contact with low surface pressure and wide contact width is established around the entire circumference. By contrast, when the eccentricity is significant, contact with the inner ridge of the seal ring in areas of large high misalignment, resulting in high surface pressure and narrow contact width. This creates a boundary between the contact area with low surface pressure and wide contact widths in areas of small misalignment. This boundary area coincided with the experimentally confirmed location of the oil leakage.