Stiebel Develops Summation Gearbox for Electric Bus Applications

Stiebel's summation gearbox is directly mounted to two integrated motors to provide full-electric operation to 12 and 18 m buses.

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In terms of energy efficiency and environmental friendliness, mobile machinery with hybrid drives are already leading the way. Nevertheless, especially in larger cities, the impact of emissions caused by road traffic is further increasing and the climate change carbon emissions becomes more noticeable. Electro-mobility alternatives are more in demand than ever before. Rapid transit, as well as urban and suburban trains or trams have a long tradition in the local public transport of larger cities. Urban buses are still using diesel fuel to a large extent and it here where it is necessary to develop ideas of efficient hybrid drives as well as effective fully electric drives. These can also be used in a climate-friendly way in diesel-electric machinery as well as in purely battery-operated city buses.

Higher operational safety and greater running smoothness

To this end, Stiebel-Getriebebau experts have developed a compact summation gearbox (type 4669) for direct mounting to two integrated electric motors. This current project is utilizing the 4669 Drive for urban buses that are ideal for full-electric applications. The energy demand can be precisely determined because the routes are fixed. The Stiebel gearbox for fully electric buses having a length of 12 m and 18 m as well as an engine power of 2 x 80 kW or 2 x 140 kW ensures a high level of operational safety and running smoothness. This is achieved by Stiebel-Getriebebau through a higher production accuracy (concentric and axial run-out) of the power-transmitting components and the strength of the block housing, as well as the components manufacture and state of the art gearing quality.

Compact and powerful

The ratios of the summation gearbox are i=2.29 (in a 12 m bus) and i=3.05 (in a 18 m bus). The power is transmitted to the driving axle of the electro-mobility vehicle by coupling the drive shaft with the differential to the driving axle and the cardan flange (Ø 150 mm) of the gearbox output. The maximum total torque at the output is T2 = 3,700 Nm. With a weight of 132 kg and overall dimensions of 620 mm x 355 mm x 260 mm the Stiebel gearbox is extremely compact ensuring optimum utilization of the available space.

Particularly designed for medium-sized and heavy electric vehicles, the Stiebel 4669 gearbox provides a customized, robust and sustainably powerful solution for a wide range of applications. Other applications of the summation gearbox such as, for example, in commercial vehicles and mobile machinery are already being planned. In this way, Stiebel-Getriebebau continues to develop electro-mobility innovations to further reduce emissions.