An axle concept for low floor, hybrid buses is being developed by ZF Passau.
Two electric motors are integrated into the axle, which are used both for traction and regenerative braking. Designed for city buses with a maximum axle load of 13 tons, each wheel is driven by a high speed, liquid cooled asynchronous motor with a downstream two stage ratio. Due to the fixed ratio, no gear changes are required. Continuous power for each axle is 120kW, rising to 240kW for short periods.
Despite the incorporation of motors, the installation space almost corresponds with that of a standard portal axle for low floor buses, which enables its use in a vehicle family of standard diesel buses without having to undertake complex modifications. Due to the low contour of the axle support, it can be installed either as a central axle or as a rear axle in articulated buses. Standard components have been used for brakes, disks, wheel bearings and seals. The axles will be offered commercially from 2010.
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