Evaluation of Advanced Lubricants for Aircraft Applications Using Gear Surface Fatigue Tests
Abstract
Surface pitting fatigue life tests were conducted with five lubricants, using spur gears made from a single lot of consumable-electrode vacuum melted (CVM) AISI 9310 steel. The gears were case carburized and hardened to a Rockwell C-60 and finish ground. The gear pitch diameter was 8.89 cm (3.5 in.). The lot of gears was divided into five groups, each of which was tested with a different lubricant. The test lubricants can be classified as synthetic polyol-esters with various viscosities and additive packages. Test conditions included a bulk gear temperature of 350 K (170 F), a maximum Hertz stress of 1. 71 GPa (248 ksi) at the pitch line, and a speed of 10,000 RPM. The following results were obtained. The lubricant with a viscosity that provided a specific film thickness greater than one and with an additive package produced far greater surface fatigue lives than lubricants with a viscosity that provided specific film thickness less than one. A low viscosity lubricant with an additive package produced gear surface fatigue lives equivalent to a similar base stock lubricant with 30 percent higher viscosity but without an additive package. Lubricants with the same viscosity and similar additive packages gave equivalent gear surface fatigue lives.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1991
- Accession Number
- ADA239501
Entities
People
- Dennis P. Townsend
- John Shimski
Organizations
- National Aeronautics and Space Administration