German Tier 1 supplier ZF said that British bus manufacturer Alexander Dennis (ADL) is expanding its product line, adding a double-decker model powered by a fuel cell drive, which is also equipped with ZF's AxTrax AVE electric drive axle to prevent local emissions.

ZF said it also provided additional hardware and software solutions for optimum performance. An initial prototype was impressive, operating at high efficiency during field testing, demonstrating the success of AxTrax AVE electric portal axle product line.

“We are delighted that the British manufacturer Alexander Dennis has placed its trust in the AxTrax AVE electric drive solution from ZF,” said Fredrik Staedtler, head of ZF's Commercial Vehicle Technology Division. “ZF has simplified the process of electrifying vehicle platforms for the manufacturer while making an important contribution toward keeping city centre mobility solutions free from emissions.”

The Tier 1 said that AxTrax AVE will be installed in a bus with a fuel cell drive in a bus, designed by ADL based on its Enviro400 product line. This configuration comprises a secure system that uses hydrogen to generate electricity, which, in turn, drives two electric wheel-hub motors in the electric portal axle. As fuel cells do not utilise fossil fuels, it will not produce any hazardous emissions, only steam. 

ADL spent two years developing this hydrogen-driven double-decker bus with ZF being a partner from the start. During field testing, the prototype operated along real bus routes in several cities throughout the United Kingdom. In addition to the AxTrax AVE, ZF also provided the inverter, the EST 54 electronic control unit (ECU) and the appropriate control software.

In this complete system, the company optimally aligned performance, efficiency and the service life of the drive. Moreover, this system solution helped reduce the test and homologation costs for ADL. 

The British manufacturer has already presented the prototype of the new fuel cell double-decker to the public as well as several fleet operators.
ZF said first introduced the AxTrax AVE in 2012 and has been successfully deployed around the world ever since. The electric drive axle can be used in a wide array of possible applications as it can not only be operated in the mentioned fuel cell configuration, but also as a hybrid or purely electrically with lithium-ion batteries.

In addition to the striking drive performance – totalling 250kW up to a maximum axle load of 13,000kg – the compact design is also appealing. Since neither a conventional unit nor a universally jointed shaft is necessary for transmitting power, manufacturers have more freedom to design the passenger area the way they want. They can add seating and standing room, for example, or provide for step-less entry and exit or a completely flat passageway.