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Wet clutches drag loss simulation is essentially linked to the clutch friction surface patterns in addition to the main geometry and conditions of the interface (relative speed, separation, inner and outer radius, viscosity and boundary pressures). The clutch patterns promote cooling flow and micro-hydrodynamic effects to aid clutch separation but greatly complicate the simulation of drag loss during separation. These drag losses are important in understanding the system losses as well as finding the most effective clutch cooling strategy. Typical clutch models either only consider simple patterns, such as radial grooves, or require significant simulation efforts to evaluate. Additionally, many simple models require calibration to measurement of the actual clutch they try to model before they provide a useful model.

One of the greatest problems in city traffic today is congestion. In reducing it, a significant role can be played by improving mass transportation by increased involvement of buses. To entice people to mass transit, it is necessary to increase passengers' comfort. From the technical side, this purpose is served by low-floor buses. To produce them, “portal”* axles are necessary. Besides comfort, vehicles must meet environment protection guidelines including the requirement for quiet operation. In building city buses to meet the new requirements, a significant role is given to the axles. One of the noise sources in buses is the system of gears in the drive axle. The noise coming from this source can be reduced by increasing the “contact ratio” of the gears, by applying fine-module hypoid gear sets in the head assemblies, by introducing so-called “high” gearing with increased contact ratio in the spur gear drives, and by increasing the production accuracy.