Szalai, G. and Kovari, P., "Development of Axles for City Buses," SAE Technical Paper 942241, 1994, doi:10.4271/942241.
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.This presentation introduces the “silent” double-reduction axles designed for city buses of medium floor height, as well as “portal”* axles with a special design.*A “portal” axle is defined as an axle where the axle body, the differential, the drive pinion and gear set have a drop compared to the center of the wheels. This drop is called the portal distance.