Theoretical and Experimental Analysis about the Gear Rattle Phenomenon in the Automotive Manual Transmissions

The article reports an investigation about the “gear rattle” phenomenon occurring in the automotive manual transmissions. In particular it has been studied the influence that may have the oil lubricant, and the various lubrication mechanisms, in reducing this undesirable event. The experimental analysis has the aim to validate a theoretical model, developed by the authors, that keeps in count the presence of oil in the “dead space” between the meshing gear teeth of the unloaded gear pairs in the no-contact phase. The results of a series of experiments conducted on an appropriate test rig for helical gear pairs, designed and realized at the Dime laboratories, have been then reported and compared with the theoretical expectations, under the condition of “idle gear rattle” varying the lubrication conditions.