Development of a Gear Oil Scuff Test (GOST) Procedure to Predict Adhesive Wear Resistance of Turbine Engine Lubricants

Abstract

The Ryder gear test has been widely used to define the antiwear characteristics of lubricating oils intended for use in aviation gear boxes. However, an accelerated procedure is required, particularly for the screening and development of new lubricants, due to the cost and complexity of the Ryder test. The present study is a development of previous work that evaluated the suitability of a number of apparatus. Initial screening work indicated that a ball-on-rotating cylinder contact geometry had the potential to effectively predict the results of the Ryder gear test. The present work describes the development of the test procedure and confirms that similar wear mechanisms exist in both instances. Indeed, the calculated contact flash temperature in both the Ryder and ball-on-cylinder contacts was almost identical at the onset of scuffing. A simple model was developed to predict the effects of lubricant viscosity on the gear contact. Excellent correlation was observed between the model and the measured effects of hydro-dynamic lubrication in the full-scale Ryder gear test. As a result, the Gear Oil Scuff Test (GOST) procedure considers both chemical and physical lubricant characteristics. A correlation coefficient of 0.92 was obtained between the laboratory and full-scale test procedures for a matrix of 27 oils of widely varying quality.

Presented at the 52nd Annual Meeting in Kansas City, Missouri May 18–22, 1997

KEY WORDS:

• Bench Tests
• Gear Lubricants
• Boundary Lubrication
• Wear
• Surface Roughness
• Scuffing

Notes

Presented at the 52nd Annual Meeting in Kansas City, Missouri May 18–22, 1997