Shift into gear
Mooketsie Edward Botha, 29, started working at Tharisa Mine in July 2011 as a truck driver. He is one of three drivers qualified to operate the T31, the only Terex TR100 powered by the new MTU S2000 engine. The monstrous truck stands a hefty 5.2 m high and weighs almost 160 t fully laden. All of that requires some serious power and Eddie, as his work mates call him, revels in the challenge. Eddie is a first generation mine worker. His relationship with powerful engines started at the tender age of nine, when he was driving a tractor on his family’s farm. His fascination with heavy machinery stuck through his studies of computer science and electronics. When he had to quit university for a job in order to sustain his young family, a move to the mine was almost inevitable.
Eddie started off driving an articulated haul truck and then progressed to the Terex TR100 T66. In April 2012 he became the first to operate the T31, the truck with the newly installed MTU Series 2000 engine. Drivers go through training and an assessment to prove that they are competent to operate any machinery. Eddie was chosen on the basis of his excellent performance record: high levels of productivity, no absenteeism and most importantly, he had no reported incidents on his shift. “All the operators want to drive the T31 because of its power. It also is less noisy than the other trucks. I enjoy driving this truck. It makes coming to work a pleasure,” he says.
“You need to be able to listen to the engine”
Eddie’s day starts at the shift -change office where all workers report before the start of a shift. Shifts are split into a morning and afternoon shift with blasting occurring between 15:00h and 16:00h on certain days. Wearing his safety pants and reflective vest with hard hat in hand, Eddie sits in on the safety and planning briefing meeting. He listens intently as his foreman announces the line-ups, loading plan and excavator allocation for the shift. Then it’s off to the hard park area where his ride for the day, the Terex TR100 T31 awaits. He effortlessly climbs up to the cabin. Next stop is the service bay to complete the inspection checklist. “You need to know your truck and be able to listen to the engine and then report any noises.” After sign-off by the shift foreman, Eddie drives the machine up a slightly elevated ramp to test the all-hydraulic brake system control. The T31 needs to give an instant braking response. Safety is top priority. If any technical issues are picked up, the machine will not be allowed to operate in the pit.
Power in the pits
Spanning a distance of between 7 and 8 km, the Tharisa Mine’s total chrome resources have been calculated at approximately 900 million tons of contained chrome. The mine has been operating since 2008 and extracts ore from the Middle Group chromatite reefs across two open pits which comprise four main layers of mineable ore of differing chrome and platinum group metals content. What seems like deserted wasteland from the distance changes rapidly the closer you get to the pit with the rumbling of a range of machinery increasing until you reach the edge of the pit. The East and West open pits of Tharisa Mine are 45 m and 70 m deep. They are busy with excavators, heavy wheel loaders and drilling machines, performing their jobs with precision and moving about in what appears to be a logistical nightmare but is in fact a thoroughly structured choreography.
The temperatures in the pit can reach up to a sweltering 40°C by midday. At 18:00h the surroundings are dusty, making it diffi cult to see through the haze. These extremities and rough terrain call for a truck with rugged construction and an engine that will perform at peak in all conditions, non-stop.
Amid the dust and assortment of machines, the T31 appears in the line-up waiting to collect a load. The excavator beeps and starts loading waste. With the precision of a well-rehearsed play it maneuvers its bucket just inches above the top of the T31 as it swings back and forth. The noise of the excavator drowns out the sound of the T31 proving the claim that the engine is less noisythan its predecessors. For about ten minutes, the earth shudders as the excavator digs into the ground to bring up another mouthful of waste, again and again, about eight times until the truck is loaded. Eddie beeps his hooter, signaling that he is ready to move off . The trucks line up to exit the pit with the T31 waiting in line. Eddie navigates the T31 up the ramp and out of the pit at the speed limit of 40 km/h. The T31 has no problem going up the ramp with a full payload. “It is tempting to see the speed to which I could push the T31 while going up the ramp but I do not want to break the rules,” he smiles, thinking of the power in his hands.
Eddie looks relaxed through the window of the cabin. His shift lasts ten hours and he has already done five. “The shifts are long but I don’t mind as it is a pleasure to drive the truck with the Series 2000 engine. I enjoy driving the T31 more than the other trucks. It needs fewer transmission shifts and you can drive it at lower engine speeds than others.” The technical explanation for this was provided by Alexander Richter, MTU product manager for Series 2000, C&I and Mining applications: “The engine develops high lugging power at low revs and this allowed us to adjust the automatic transmission control unit so that it remains longer in gear when lugged down, where the original engine already needs a downshift .” That saves fuel as well as making operation much quieter. “I can really feel the power of this new engine,” says Eddie and adds with a smile: “Especially when I’m going up the ramps with a full load.”
Thys Redelinghuys is the MCC Group Plant Manager for Tharisa Mine. He has overseen the day-to-day running of the plant since 2009. Thys is pleased with their year-long partnership with MTU and he is particularly impressed with the performance of the Series 2000 engine. “The Series 2000 gives a powerful performance in high temperatures and differing altitudes. It runs more silently because of the new combustion system and the shifting of the transmission is smoother. Low downtime is important for our production output.” For Thys, engine reliability is especially important because an immobilized truck means big losses. Another major cost factor at the mine is fuel. “Our fuel records since commissioning of T31 with the new MTU engine show, that it burns up to 25% less fuel than the remaining TR 100s in Tharisa, which are powered by the engine of a competitor,” he said.
Achieving low fuel consumption was one of the major targets of the MTU engineers who developed the engine. Consumption is 10%less than on its predecessor. Life-cycle costs have also been cut by 8%. In addition, the engine is the only unit in its class which meets US EPA Tier 4i emissions targets without using an exhaust aftertreatment system. “The new engine gives customers a clear advantage mainly as a result of low fuel consumption and perfect acceleration thanks to improved torque development across the entire speed range,” explained Alexander Richter. “We achieved that with the intelligent combination of common rail injection technology and two-stage turbocharging,” he added. Thys Redelinghuys is particularly happy with the reliability of the engine. “The truck has already logged up 2,500 hours with this engine and it has never been in the workshop except for scheduled maintenance,” said the South African. And if anything should come up, a service technician will be sent out from MTU South Africa in Johannesburg for on-site work. No coming between a man and his T31 At 02:00h, Eddie has finished his shift . Do the long hours in the cabin on his own get to him? “Even though we drive on our own we still operate as a team and communicate a lot. It is important to work together. We cannot have any arguments or tension among us when working in the field. We have to be clear when communicating with the walkie-talkies about our line-ups so that we don’t cause delays and slow down production.”