Test results:

Road testing commenced on August 16th, 2004 to confirm the theoretically calculated and bench test verified, efficiency data. On October 14 2004 TNO, a leading independent Dutch research institute certified the below summerized results:

History:

Finally on April 6th 2004 the X97 arrived from Veldhoven at our new location in Apeldoorn for transformation into the e-Traction® Bus - Technology Demonstrator. The traction motor, which had originally been designed for use in streetcars and its differential, with a 5:1 power transfer ratio, together with just about everything needed to make those components function had, at our request, already been removed by this time. The bus had also received a new color scheme consistent with that of our company.

Its A-frame rear axle had actually already spend some time in Apeldoorn earlier in the year to be minutely measured as a new identical axle had to be made that would be suited to receive TheWheel™ SM500/2FE units, while maintaining the original brake configuration. Our long term partner, Besaris B.V., built the new rear axle to our specifications and is performing most of the mechanical adjustments in close cooperation with us.

Maintaining the original brake system means that all the original test data have remained valid and will facilitate the approval process by the regulatory bodies. For practical purposes though this braking system will rarely be used. To optimize energy efficiency the e-Traction® Bus will mostly rely on regenerative braking, whereby the kinetic energy is converted back into electricity. The conventional brake system will only be used in emergency braking situations and for parking.

Meanwhile the newly designed TheWheel™ SM500/2FE units were being assembled. A Michelin super-single tire, model XDU 455/45R22.5, and our custom-made and designed rims had already arrived. The diameter of these tires required an enlargement of the rear wheel well. Once the exact tire specifications had become known in December 2003, the required alteration in the composite structure could be conducted by Niek Smink of Bustech B.V., the original project manager, under the guidance of the original builders of the bus, Stork Fokker AESP Aerospace Group.

The generator compartment was completely emptied. The generator was stripped of its soundproof housing, because it seemed more practical to soundproof the entire rear compartment instead. The noisy pneumatic and hydraulic pumps and the heating unit have all been housed in that sound and heat insulated space. The generator's exhaust pipe runs to the roof where the muffler has been placed, far removed from pedestrians. Fresh air is brought in from two locations to ensure proper running of the diesel generator and ventilation of this compartment.

The large pieces of equipment have been cleared of the roof. The inverter had become obsolete as this function is already built into every TheWheel™ (and e-Traction® SM350) unit. The device used to dissipate the kinetic energy from braking was similarly removed as the batteries will now be able to conserve this energy. As a consequence the box on the roof can be shortened to almost the length of the first prototype for a more pleasing visual impression.

Aside from the visual impact there is, however, a much more significant technical benefit. Previously the energy from the generator was channeled to the inverter on the roof before going back down to the traction motor. Conversely the regenerative energy from the traction motor during braking was dissipated in a device on the roof. While the distances between these devices caused a significant loss of energy this arrangement also posed a significant electrical conductivity and electromagnetic interference problem that could only be solved with heavy cables and shielding. Just note the thickness of the cables that came in and out of the original inverter box for the single motor in the image below.

The electronics are undergoing a dramatic change. TheWheel™ SM500/2FE is normally operated via an Inter Control Digsy CANopen system. It therefore made sense to convert the entire electronic suite to the same standard for simplicity and ease in programming and operation. Incidentally, if the CANopen system were ever to fail, the e-Traction® Bus can also operate on a manual by-pass that allows limited, forward and reverse, speed operation.

Four Lithium-ion test batteries arrived in June 2004 and were tested on the e-Traction® Kart. They measured up to our expectations and a further 28 units replaced the lead-acid batteries used during the initial trials after the aforementioned TNO fuel consumption measurements tests were completed.

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Last modified: June 12, 2007