Time to recharge
Posted on 30 March 2010 by Elke Brown, Images by Eddie Madariaga
MTU technicians can repower a haul truck in just a few days.
Years of heavy work in the bone-dry Chilean desert and thin, high-altitude air take their toll. And age is creeping up. The power – though always dependable – is waning and it gets more difficult every day to perform the daily tasks. High time, then, for the patient’s internals to undergo a course of treatment. The magic cure? Repowering.
Fully laden, the behemoth drags itself slowly out of the mine pit in the dry and dusty heat. After nearly an hour it reaches the upper plateau exhausted. In recent times its strength has noticeably faded. For years it has toiled ceaselessly without even allowing itself a day’s rest. But now it costs a lot of energy to complete the daily quota. Too much energy in the opinion of its employers. Although it is a long way from the scrap heap yet, its power is definitely not what it once was. But some new internals should put that right and extend the dump truck’s life expectancy by many years. In just a few days the old engine will be replaced by a gleaming new MTU Series 4000 diesel power unit.
Such unbroken continuous duty is not without consequences. The performance capacity of the engines diminishes over time, while the running costs rise due to wear and higher fuel consumption. And the risk of failure – a horror story for the operator – increases. Because every week that a dumper stands idle, the mine operator is faced with a six-figure loss.
Vehicles made by Hitachi, Le Tourneau, Liebherr, Belaz, Komatsu and Terex can easily be refitted with Series 4000 engines.
Often the package includes a matching radiator and air intake and exhaust systems along with the new engine. So the customer gets all the necessary parts for repowering from one supplier. Despite undergoing a major transplant, the dump trucks require very little recovery time. Once the right replacement engine is ordered, it takes no more than a week including installation and system configuration for the vehicle to be back on its wheels and ready for thousands more hours of continuous duty. And to make sure that the engines continue to perform to their full capabilities long after the operation, MTU takes care of all future health checks. The 30-strong team looks after the nearly 60 engines that drive the copper mine’s heavy-duty vehicles. The technicians know their “charges” inside out and see to everything from filter replacement and oil changes through to regular services. In order to avoid expensive breakdowns, the experts are available 24 hours a day, seven days a week, 365 days a year.
The cooled turbocharger ensures that the engine delivers consistent performance even at high ambient temperatures. The electronic engine management adjusts the most important operating parameters such as injection volume and pressure to suit the onsite conditions. So even at altitudes up to 3,600 meters where simply breathing is difficult, the turbocharger can still reliably deliver the charge air at a boost pressure of around 2.5 bar. The Series 4000 also features the latest-generation electronically controlled common-rail fuel-injection system, which MTU has been fitting as standard since 1997, having been the first manufacturer of large-scale diesel engines to do so. It atomizes and delivers the fuel at ultra-high pressure so that only the precise amount required for the work being done is used. And what is so special is that, compared with preceding models, the latest version consumes around five percent less fuel. At the same time it is kinder to the environment because the MTU Series 4000 engines not only satisfy the emission restrictions demanded by the US EPA Tier 2, but also meet all the requirements for compliance with future exhaust emission limits.
After a series of thorough tests, the patient is discharged from the care of the engine health professionals. With new-found zest it accelerates to 60 kilometers an hour then quickly slows down to descend the switchbacks into the deep mine crater. It’s difficult to believe that it was struggling up these slopes only a week ago. And now it is looking forward to being able to carry hundreds of tonnes of copper ore out of the mine again. And to being restored to full power by the engine doctors if it should ever be necessary again in the future. Which is what repowering is all about.