Experimental Test Rig for the Evaluation of Oil Squeeze Effects between the Impacting Teeth of a Meshing Gear

The paper describes a test rig for the experimental validation of theoretical models to analyze the automotive drive-line dynamic behaviour accounting for the presence of oil between the impacting teeth of the gear pairs. The rig is constituted by a single gear pair, driven by an electric motor controlled in speed by an inverter. The peculiarity of the rig is its versatility in order to compare various gear pairs with different tooth parameters and different lubrication conditions. In particular the experimental study regards the acquisition of vibrations, originated during the impacts of an unloaded gear pair, responsible of the “gear rattle noise” phenomenon. At the present the automotive manufacturers investigate experimentally the gear rattle phenomenon generally comparing different cases by the measures of the noise level using microphones. The study aims to measure the gears relative angular displacements of an unloaded gear pair by two encoders, fitted on the primary and secondary shaft, and successively reconstructing the relative motion of the teeth along the contact line. Some results of the first experimental tests, conducted in dry conditions, are reported. The results confirm the test rig capability in detecting the relative motion between the impacting tooth.