At Visby, on the Swedish isle of Gotland, Scania and Siemens are developing a dual powered (diesel and electric) truck that operates in electric mode by drawing current from overhead wires.
The companies are looking forward to demonstrating the electric truck on the road between Pajala and the iron mine at Svappavaara in far northern Sweden, if the route can be equipped with overhead power cables.
“This is one of many different projects Scania is working on to identify new fuel-saving future alternatives,” says Sara Bengtsson, manager, Scania public affairs.
In an around-the-clock operation, trucks hauling iron ore will travel the 150 km or so to Svappavaara where the freight is transferred to the Iron Ore Line (Malmbanan), a railway that will carry the ore to a port on the Atlantic coast of northern Norway.
In a recent report, the Swedish Transport Administration (Trafikverket) stated that electrically-powered trucks, using either overhead cables or rails in the road, are a realistic alternative to conventional diesel powered units. However, an overhead conductive power supply is believed to be the only realistic solution for this service, since the road is built over bogs and moves up and down.
“Development of our electrified vehicle has to take place on a step-by-step basis,” explains Johan Lindström, an expert engineer at Hybrid Systems Development, NBB.
“We are using electrified gearboxes that were developed in hybrid projects, but then a large electric motor must be added to the powertrain in order to drive the 90 tonne vehicle entirely by electricity.”
Siemens’ technology ? known as eHighway ? resembles the trolley buses of old but is far more advanced. Systems in the truck detect whether there are overhead cables via a laser sensor and if detected the current collectors are automatically deployed.
A hall sensor monitors that the truck follows the cable, and the current collectors move backward and forward laterally to ensure continuous contact.
Siemens has built a four kilometre long test track near Berlin, Germany, and says the challenging part was not building the overhead cables, but building the systems that will allow the truck to be rapidly connected to and from the power supply, for example while overtaking, when the truck is instead powered by its diesel engine.
The Swedish Transport Administration has proposed that overhead cables should initially be placed along a 12 kilometre stretch of the Pajala–Svappavaara road in order to gain experience for continued development.