The first Class 7100 electric locomotives built by Siemens for Pacific National, Australia’s largest private rail freight company, are already hauling trains over the tracks in Queensland. Pacific National ordered a total of 23 of these electric freight locomotives and plans to deploy all of them for coal transport. All of the locomotives are to be built and tested at Siemens’ plant in Munich-Allach.
The heavy-duty Class 7100 locomotive has six axles and weighs 132 metric tons, a full-length Pacific National coal train weighs 12,720 metric tons. The trains of this size that were previously pulled by five conventional locomotives with Direct Current traction systems can now be hauled by three of these Class 7100 units. They are able to transport these heavy loads thanks to the modern Alternating Current traction locomotives designed by Siemens, with an output rating of 4,000 kW and a maximum speed of 80 km/h. Two units are coupled up front of the train, while the third is arranged in the middle. The unit reduction from 5 conventional locomotives to 3 new 7100s is made possible by an excellent slip control used in combination with efficient AC three-phase propulsion.
The special equipment needed for these trains includes the Electronically Controlled Pneumatic Brake (ECP). An electrical connection ensures that all freight cars receive the braking command simultaneously and without delay due to pressure changes in the brake pipe. This ultramodern brake system is able to bring a train weighing nearly 13,000 metric tons and traveling at a speed of 80 km/h to a full stop after a distance of 650 meters. Usually braking distances are twice that long. The third locomotive located in the middle of the train is also connected to the ECP cable and is not radio-controlled.
Besides substantially lowering the maintenance costs, Siemens Mobility has also succeeded in reducing energy consumption in comparison with the predecessor locomotives. Consequently, the replacement of five older units by three new Class 7100s will produce savings of up to 2,100 kWh and, in regenerative feedback mode, another 4,500 kWh over a route length of about 380 kilometers. These new freight locomotives not only reduce the operator’s energy costs, they also contribute to a lower CO2 impact.