An Experimental Investigation of the Effects of Lubrication on Rattling Motions and Noise of a Gear Pair

Abstract Vibro-impacts are common in various automotive power transmission applications. They lead to noise issues known as rattling. Input or output toque fluctuations cause gear teeth to separate and commit to complex sequences of drive and coast-side impacts spanning the entire backlash zone. Several recent experimental and theoretical studies characterized the underlying nonlinear structure of the rattling behavior of gear systems, ignoring any influences of lubrication conditions. Those rattle models with no lubricant provisions were shown to compare well with the dry contact measurements. This experimental study aims at complementing these earlier studies providing acoustics and torsional vibration measurements from a single gear pair excited by input torque fluctuations as it operates dry, jet-lubricated and dip-lubricated conditions. A rattle test machine equipped with a lubrication system is presented. Corresponding vibro-impact and sound pressure measurements are provided for a wide range of operating and lubrication conditions. Noise and torsional vibration data under different lubrication conditions are compared directly to quantify the influence of lubrication on the resultant rattle behavior. Presented results with dry, dip and jet lubrication show that lubricant provides some additional damping in the process reducing the noise level to a certain extent while overall vibro-impact behavior remains intact.