Rotary Shaft Seals: The Sealing Mechanism of Synthetic Rubber Seals Running at Atmospheric Pressure

Abstract

The paper describes an investigation to establish the mechanism by which sealing is achieved in the conventional synthetic rubber oil seal when used on a rotating shaft. After demonstrating that the contact between the seal and the shaft cannot be dry contact—that there is in fact what appears to be a coherent film of oil between the sealing lip and the rotating shaft—further experiments are described to find out why the oil in the film does not flow out past the seal. The conclusion is reached that there is a meniscus at the oil/air interface and that retention of the oil in the oil film is effected by the surface tension of the oil.