Investigation on Influence of Circumferential Velocity and Lubrication Oil Grades on Scuffing and Thermal Efficiency of Gearbox

Abstract

Lubrication oil grades plays major role in reducing the friction to prevent scuffing in gears. Gears transmit power through rolling/sliding contacts between teeth, which must operate reliably for designed life with reduced friction so that there will be minimum wear. Lubrication of tooth contacts, both as a means of minimizing scuffing and as a means of reducing friction due to sliding, is therefore of crucial importance. The circumferential velocity of high speed gearboxes and oil grades plays major role in thermal efficiency of gearboxes. In gearboxes with oil sumps, churning losses contribute for significant portion of the total power loss. Present empirical approaches for examining the churning losses are often limited to certain constraints and operating conditions. Furthermore, they do not provide any information about the oil distribution in the gearbox. In order to overcome these shortcomings, we investigated a steel mill gearbox failure with analytical tools and simulations with the help of renowned software packages and predicted the thermal behavior of the gearbox as function of oil grade and circumferential velocity, also validated later at application.