AGMA 17FTM02 PDF

Sustainability is becoming one of the most important aspects within the power transmission business. Users demand low-maintenance drive systems with as little disruption as possible and expect lifetimes of more than 10,000 hours. Approximately 40 percent of long-term gearbox leakages can be traced back to poor interaction between the Radial Shaft Seal (RSS) and the lubricant. Thus, it becomes essential to analyze the tribological system as a whole, which includes the gear oil, seal grease (if required), elastomer material and design, and the shaft. This paper highlights the most critical interactions between the industry’s most commonly used gear oil formulations, with emphasis on synthetic oils, with Nitrile- and Fluoroelastomers. Herein described are wear modes for Radial shaft seal (RSS), such as the change of dimension, seal lip wear, and shaft run-in.

The report also contains evidence of how polarity of the base oils and the additives alter the swelling and shrinking behavior, which eventually have an impact on the sealing function. Chemical and physical reactions between the lubricant and the elastomer were space-resolved with the help of Image Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) analysis as well as Nuclear Magnetic Resonance (NMR). Through the newest micromechanical measuring system developments, one was able to determine the difference of the mechanical properties in the sealing lip area within µm. It was proven that certain oil formulations merely changed the mechanical properties on the surface of the RSS. Typical immersion testing would not show any significant differences regarding the mechanical properties, but under long term dynamic testing, those oil formulations show considerable wear and eventually leakage of the RSS. It was proven that through an ideal combination of base oil and additives, the demand of life expectancy on the radial shaft seals can be met.