APPLICATION OF EHL (ELASTOHYDRODYNAMIC LUBRICATION) THEORY TO GEAR LUBRICATION

The concept of EHL (elastohydrodynamic lubrication), and simplified equations for calculating the isothermal elastohydrodynamic lubricant film thickness between meshing gear teeth, are presented. The only physical property of the lubricant required is the lubricant parameter (LP), which combines both the viscosity and the viscosity-pressure characteristics. The value of LP can accurately be determined by direct measurement of the oil film thickness in an optical EHL apparatus. Since LP is dependent on temperature, measurements are made at different temperatures and the data presented in the form of charts of LP vs. temperature. The quality of lubrication of gears can be expressed as the ratio of the EHL film thickness to the composite surface roughness of the gear teeth, frequently called the specific film thickness. Data relating the probability of gear distress to the specific film thickness are reviewed. Lubricant selection for a desired value of the specific film thickness can be made through LP. Under certain operating conditions the EHL film thickness may be significantly less than that calculated from theory. Correction factors are provided for nonisothermal conditions and for lubricant starvation in the EHL contact of meshing gear teeth. Effects of viscosity index improved and non-Newtonian oils are considered.

• Supplemental Notes:
  • Presented at SAE Earthmoving Industry Conference, Peoria, Illinois, 14-16 April 1980.
• Corporate Authors:

  Society of Automotive Engineers (SAE)

  400 Commonwealth Drive
  Warrendale, PA  United States  15096
• Authors:
  • Jackson, A
  • Rowe, C N
• Publication Date: 1980

Media Info

• Features: References;
• Pagination: 14 p.

Subject/Index Terms

• TRT Terms: Gears; Lubricating oils; Pressure; Viscosity
• Old TRIS Terms: Elastohydrodynamic lubrication
• Subject Areas: Safety and Human Factors;

Filing Info

• Accession Number: 00376859
• Record Type: Publication
• Source Agency: National Highway Traffic Safety Administration
• Report/Paper Numbers: SAE-800670, HS-030 004
• Files: HSL, USDOT
• Created Date: Jul 30 1983 12:00AM