5. Conclusion

Models of the linear behavior of the various components in the complete powertrain highlight the main torsional vibration modes responsible for the most frequently encountered noise problems, both in neutral and in engaged gear.

In neutral, the so-called "neutral" noise results from the clattering of the idler gears inside the gearbox. In the absence of a clutch pre-damper, the system reduced to flywheel, clutch and gearbox primary has a mode generally centered around 2,200 rpm. This mode is amplified around idle speed, so that the acyclism on the gearbox side is greater than the acyclism on the engine side, and of sufficient energy to excite the gearbox. For this reason, most clutches are equipped with pre-dampers, enabling the above-mentioned mode to be reduced to below 500 rpm. With this system, filtration in neutral becomes excellent, with gearbox-side acyclism...