When Sandvik developed its new Sandvik TH550 and TH540 underground trucks, the company started by getting the big picture to answer an important question: What are the real factors that affect productivity and operating costs for these types of vehicles? Product manager Mark Ryan at Sandvik thinks that the way forward is to look at overall costs and productivity of a mine, and that you don’t achieve as much as you might think just by making underground trucks go faster.

“Mines are getting deeper and the haulage distances longer, with higher operating hours per day being scheduled,” Ryan says. “Increasing the maximum speed does not guarantee more production per shift. More operational hours per year is the key.”

Field studies and other analysis showed that other factors need to be considered besides just the trucks’ technical performance in terms of power and speed. You also have to consider their impact on the environment. “One of the big costs that mines have is ventilation, so we decided to go with more efficient and cleaner engines,” Ryan says.

This is why the TH550 and TH540 come with two engine choices that meet the emission levels set out by Tier 2/Euro Stage IIA or Tier 4i/Stage IIIB. They are two emission standards that regulate the maximum levels of nitrogen oxides (NOx) and particulate matter for diesel engines (DPM) in off-road vehicles, as mandated by legislation in different parts of the world. Although transitional rules allow manufacturers certain flexibility in the implementation of these standards, Sandvik has decided to be in the front line with this new technology in underground applications.

In addition to low levels of NOx and DPM, the new trucks offer lower fuel consumption than the earlier T50 and T40 generation, but with more torque. High-efficiency engines generate less heat than higher-powered engines while doing the same amount of work.

“The engines work smarter, not harder,” says Ryan. “The ventilation and fuel requirements for these trucks are the lowest in the market.”
A key word when it comes to productivity is uptime, and lower fuel consumption obviously extends the refuelling intervals. Sandvik’s engineers have also designed other uptime-increasing features for the TH550 and TH540, adding to the proven reliability of the earlier generation of Sandvik trucks.

One example is the electrical wiring and VCM (vehicle control and management) system. Components that can be negatively affected by water in the mine, such as wire harnesses and battery packs, have been mounted higher up on the vehicle for better protection. In addition, there are fewer wires and relays, to reduce the number of possible failure points. Everything is connected to the VCM system with an interface that displays the vehicle status in real time.

“It won’t fix the problem, but it will help identify the problem area much quicker,” Ryan says. “This means there will be much more uptime due to less time needed for troubleshooting.”
The TH550 has a payload capacity of 50 tonnes, while the TH540 is rated at 40 tonnes. A look under the hood reveals a 603hp/450kw Volvo TAD1661VE for the TH550 and a 543hp/405kw TAD1660VE for the TH540. These engines give the two underground trucks a high power-to-weight ratio, which combined with a high payload per envelope size and empty vehicle weight give an overall performance advantage in underground applications. “We chose Volvo because they came up with the best solution for our application,” Ryan says. “Overall it is a good engine that is reliable and fuel-efficient.”

The emission limits set out in Tier 4i and Stage IIIB are met through an aftertreatment system for the exhaust. This includes a selective catalytic reduction (SCR) unit with a urea injection system. SCR is a technology where dangerous NOx is converted to harmless nitrogen (N2) and water (H2O), with the help of a catalyst. The combination of efficient engine design and SCR technology results in reduced DPM and NOx.

The approach Sandvik chose for the new underground trucks has been to take a wider perspective instead of just cranking up the power another step.
“This also brought us back to one of our core values: to offer the lowest cost per tonne hauled,” Ryan says.

Åke R Malm