Two other machines are on order for a major customer in Queensland, with more in the pipeline, according to Sandvik Mining and Construction’s product line manager for underground flameproof load-and-haul equipment Richard Osborn.
“We are now looking at exporting these to major overseas markets, including South Africa, China, and eventually the US,” he said.
Sandvik’s 7-tonne LS171 and the 10t LS191 deliver lower emissions, increased safety and ergonomics, better power and torque delivery and easier servicing, according to Osborn.
Both loaders are powered by a low-emission Tier 3 Caterpillar C7 engine through a Sandvik-specified electronic engine management system, for reduced emissions, improved performance and lower fuel consumption.
“The underground coal mining industry has been crying out for Tier 3 engines for many years, because they are so much cleaner,” Osborn said.
“While we can achieve the required emission levels on Tier 2 and even Tier 1 engines, Tier 3 engines give a major reduction in NOx emissions, as well as further lowering particulate emissions.”
The Cat C7 ACERT engine delivers gross power of 172 kilowatts at 2200rpm and maximum torque of 940 Newton metres at 1650rpm (up 25% on the previous models), giving greater tractive effort and increased towing performance.
This engine is controlled by a Sandvik-specified electronic management system specifically designed for underground applications.
Both the LS171 and LS191 loaders share a high degree of parts and components commonality, including the engine electronics and some drivetrain components, with the main difference being in the hydraulic systems of the two machines.
The LS171 uses a conventional fixed displacement hydraulic system for its loader system, based on a proven design that is robust and easy to repair, while at the same time incorporating upgraded pumps for higher efficiency.
The LS191 – as with its predecessor the LS190 – has a pressure compensating hydraulic system which allows it to act as a prime mover unit for Sandvik’s 50t hydraulic drive roof support trailer, used for relocating longwall shields and equipment.
This pressure-compensating hydraulic system allows the LS191 to efficiently deliver hydraulic power to drive the trailer, for faster, more effective moving of large longwall components.
An upgraded hydraulic system features new, more efficient pumps to allow a reduction in engine speed – 2300rpm compared with 2600rpm for its predecessor – resulting in lower noise levels.
The engine’s electronic management system – which has been specifically developed by Sandvik for underground operations, in close consultation with customers and engine and electronics systems suppliers – meets the latest underground mining requirements.
To comply with underground explosion protection requirements, all exposed field devices for the engine electronics are either intrinsically safe or encapsulated.
In addition, the electrical components have been fully certified by Australian certification authorities.
Osborn said other major changes to both machines included safety, cabin ergonomics and serviceability.
“In terms of easier and safer maintenance, we have moved major components so that all daily and weekly check points are at ground level,” he said.
“Only service points for 250 hour and greater service checks require access to the top of the machine – and we’ve greatly improved access there.”
In the cab, the operator’s display includes details such as solenoid status, pressure switch status, faults log and engine diagnostics, so if there is an issue, the operator can quickly and easily let the maintenance technicians know what’s causing it.
“That makes troubleshooting much quicker and easier, plus service technicians can plug in specialist diagnostics tools, while data logs, giving a complete log of all machine activity and conditions, can be downloaded to a laptop,” Osborn said.
The Caterpillar C7 engine system used in the new units meets the requirements of AS/NZS3584.2:2008, the latest version of the standard for diesel engines used in underground coal mines.
“We have put a lot of time and effort into assessing the safety performance of the engine control system,” Osborn said.
The braking system has also seen safety-related improvement, with the safety-related parts of the braking control system meeting AS4024.1501 Category 3 requirements.
Stability levels have also been improved, while both loaders are fitted with Sandvik’s fully ISO-compliant (to ISO 3471:2008 and ISO 3449:2005) ROPS/FOPS operator’s canopies, available in a range of heights to suit different minesites and operations.
Noise levels have been reduced significantly through the fitting of new engine bay covers, which have been designed so that operators and maintenance personnel are discouraged from leaving them open during operation.
In addition, a temperature-controlled fan only runs at full speed if it needs to, further contributing to lower noise levels.
Other safety and operational features include in-cab engine/shutdown system diagnostics, wet scrubber system and improved cabin ergonomics and layout.
There have been major changes to the cabs on both machines.
“We’ve removed everything above the operator’s eye level to improve visibility and minimise distractions – and greatly improve safety – plus we have incorporated a detailed operator’s display,” Osborn said.
A self-levelling seat in the cab always returns to the same height for greater comfort, plus it self-adjusts to the weight of the operator.
Cabin access/exit improvements include wider doorways and three points of contact.
“While environmental legislation in some jurisdictions still doesn’t require low-emission engines for underground mining, demand is being driven by the mining companies who are insisting on the highest environmental and safety standards for their operations globally,” he said.
“These loaders really represent the future of underground coal loaders for us.”