Power loss performance of high pressure nitrided steel gears

Abstract

Environmental issues are leading to continuous search for more efficient solutions; in this work the influence of high pressure nitrided steel gears in combination with a bio-lubricant was analysed. So, power loss tests were performed on the FZG test rig, using carburized (C) and high pressure nitrided (N) steel gears and two different lubricants. The operating temperatures of the oil and of the FZG gearbox wall were measured for different values of the input torque and speed. At the end of the tests, the gear mass loss was measured, and the tooth flanks were inspected, looking for typical surface failure mechanisms. Using an energetic model of the FZG test gearbox it was possible to quantify the influence of lubricant formulation and gear materials on the average friction coefficient between gear teeth. The tests results showed that for the conditions tested the high pressure nitrided steel gear had lower dependence of lubricant type than a carburized steel gear and when a mineral lubricant was used the nitrided gear also promoted lower stabilization temperatures. The nitrided steel gear showed higher wear with both lubricants tested.