ZF Equips Fuel Cell Bus with Electric Drive System

• First application of ZF’s AxTrax AVE electric portal axle in a fuel cell configuration by ADL
• ZF delivers a system solution for optimal performance
• New prototype bus performs impressively during field testing

Friedrichshafen/Larbert, Scotland. The British bus manufacturer Alexander Dennis Ltd. (ADL) is expanding its product line, adding a double-decker model powered by a fuel cell drive. This new model is also equipped with ZF’s AxTrax AVE electric drive axle to prevent local emissions. ZF also provides additional hardware and software solutions for optimum performance. An initial prototype is now operating at high efficiency in field testing.

This new application is further evidence of the success of the 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,” says 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 center mobility solutions free from emissions.”

The AxTrax AVE will be installed in a bus with a fuel cell drive. The bus, designed by ADL, is based on ADL’s Enviro400 product line. This configuration comprises a secure system that converts hydrogen into electricity, which, in turn, drives two electric wheel-hub motors in the electric portal axle. As fuel cells do not utilize fossil fuels, they produce no hazardous emissions, only steam.

Partner in the system

ADL spent two years developing this hydrogen-driven double-decker bus with ZF selected as a partner from the beginning. During field testing, the prototype operated along actual bus routes in several cities throughout the United Kingdom. The Enviro400 design impressed everyone with its outstanding efficiency.

In addition to the AxTrax AVE, ZF also provided the inverter, the EST 54 electronic control unit and the appropriate control software. In this complete system, the company aligned performance, efficiency and the service life of the drive while reducing 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.

Efficient and proven

The AxTrax AVE was introduced in 2012 and has been successfully deployed around the world. The electric drive axle can be used in a wide array of applications as it can not only be operated in the fuel cell configuration, but also as hybrid or purely electrically driven with lithium-ion batteries. In addition to the excellent drive performance – totaling 250 kW up to a maximum axle load of 13,000 kilograms – the compact design is also advantageous for packaging considerations.

Since neither a conventional unit nor a universally jointed shaft is necessary for transmitting power, manufacturers now have more freedom to configure the passenger compartment to their design preferences. They can add seating and standing room, for example, or provide for step-less entry and exit or a completely flat passageway.