Capital Equipment News June 2021

A total of 38 T284 trucks are currently running on the Liebherr Trolley Assist System at mine sites, mostly in Panama and Zambia.

enablers for the zero-emission mine sites of the future.” He says Liebherr’s “20 years-plus” of success in this field stems largely from the company’s vertically integrated Litronic Plus AC power drive system which, when combined with a powerful diesel engine, yields higher speeds on grade while enabling trucks to haul more material in less time. “The Litronic Plus drive system uses maximum available engine power to deliver smooth acceleration and consistent speeds on grade, leading to reduced load spillage,” says Munch. Diesel-electric technology Developed and built by Liebherr, the Litronic Plus diesel-electric AC drive system maximises power conversion into mechanical torque. The diesel engine and traction alternator generate AC power, which is then converted into DC power to supply a common DC Bus. “Insulated-gate bipolar transistor (IGBT) frequency convertors transform the power back to an AC waveform, which drives each of the rear wheels and traction motors,” says Munch. “The IGBT frequency convertors enable continuous variable-speed control of the traction motor, from zero to maximum speed.” By extracting optimal power from the diesel engine, the drive system makes more power available for acceleration on inclines, while conserving fuel. “The Litronic Plus system optimises electrical, mechanical and hydraulic power distribution while minimising fuel consumption when the engine is idling. This also reduces CO 2 emissions,” says Munch. “Our goal is to use as much of the

The growing interest in diesel-electric technology in rigid dump trucks is driven in part by the need to reduce CO 2 in mining

Liebherr’s 20 years-plus experience in electrical drive systems stems from the combination of its Litronic Plus AC power drive system and a powerful diesel engine

By extracting optimal power from the diesel engine, the drive system makes more power available for acceleration on inclines

With Trolley Assist, onboard pantographs connect the truck’s drive system to overhead power lines

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truck’s load-carrying capacity as possible for payload.” Advantages The advantages of diesel-electric drive systems over traditional mechanical drive technology include reduced maintenance costs and lower total oil consumption. “The reduced cost of the additional cooling system for downhill, loaded

operations also results in less service time,” says Munch. “With the IGBT system, the drive system power components are liquid cooled to maintain optimum component temperatures. This leads to maximum reliability and reduced maintenance requirements.” Diesel-electric products Liebherr offers a full range of diesel-

CAPITAL EQUIPMENT NEWS JUNE 2021 17