As mine output goals intensified and haul trucks increased in size, manufacturers typically built bigger excavators to match. A common rule of thumb
recommends three to five passes per loading cycle for maximum productivity; that is what drove the development of the largest hydraulic and electric rope
shovels currently available.
But productivity per se is not necessarily the top focus for shovel users or producers. “The industry today has really shifted the focus of original
equipment manufacturers toward cost per tonne rather than simply maximizing productivity,” says James Roush, electric rope shovel and dragline new product
introduction and strategy manager at Caterpillar.
In late-2013, Caterpillar dropped its previously announced plans to build the highest-capacity hydraulic mining shovel yet. The 6120B H FS would have been
able to move 363 tonnes of material – the capacity of a CAT 797F truck – in as few as three passes. But the mining downturn that immediately followed its
announcement at MINExpo 2012 killed the program budget.
Instead, CAT invested in its existing models. According to CAT spokespeople, the most exciting development is an energy storage mechanism that will lighten
the load on 7495 and 7495 HF electric rope shovels. Energy created during swing deceleration and bucket-lowering is stored in ultra-capacitors, and then
used to power high-demand activities. The electric shovels still require generators but only about four megawatts’ worth – as opposed to eight megawatts or
more on the existing models.
Caterpillar calls this approach the Power Demand Management system. “As the most efficient off-grid power solution available, CAT rope shovels with Power
Demand Management technology offer new possibilities for opening greenfield sites and will help rope shovel operations anywhere become even more productive
and cost effective,” says Ruth Haws, CAT’s electric rope shovel and dragline commercial manager. She adds that new projects with a focus on cost per tonne,
availability and durability are being incorporated into future model releases and will also be available as retrofits to existing machines.
Brian Mace, product marketing manager at Hitachi, reports that keeping up to date with technology for better reliability has guided Hitachi’s excavator
program. Six to seven years ago, when Hitachi introduced its current excavator models, it focused on improving remote monitoring capabilities. An
all-hydraulic system became electric-on-hydraulic, with a new set of operator controls. “We took out all of the older analog-type gauges and put everything
onto a digital monitor for the operator,” says Mace. “So everything’s on one screen for ease of operation and looks at how the machine’s performing.”
Mace sees this as a general transition toward greater autonomy. The current controls allow operators to do some troubleshooting directly from the cab, and
as this technology becomes more prevalent, he suggests it will open pathways to remote operation. Hitachi already has an autonomous haulage program, with
trucks undergoing trials at the Meandu coal mine in Australia. “I’d say after that, within five years or further out, we may see that adapted to the
shovels,” predicts Mace. “I would say on the shovels, it’s probably more remote operation sooner than autonomous.”
Mace suggests that safety concerns could also drive design changes in the future: “We’re seeing more and more emphasis around the operator regarding noise
level exposure and vibration exposure. So those will definitely affect the design if there are major changes planned to what is currently available.”
In the meantime, Hitachi’s next redesign will enhance onboard monitoring and diagnostics. But most importantly, it will bring the machines’ diesel engine
emissions up to scratch for the American, Canadian, and European markets. The current line meets the U.S. Environmental Protection Agency’s Tier 2
standards; starting in 2015, any new models will need to reach near-zero Tier 4 levels. The release date has yet to be determined.
Alexander Hochgürtel, marketing assistant at Komatsu Mining Germany, agrees that remote monitoring will become increasingly relevant. He feels that Komatsu
has already established expertise in this type of technology: for the last decade or so, Komatsu has had a monitoring kit, KomtraxPlus, that gives
customers access to machine data and key performance indicators, runs self-diagnosis, and can transfer data via satellite to the web.
In Komatsu’s latest tweaks to its hydraulic excavators, basic maintenance has played a stronger role. “Komatsu has done massive investigations on its boom
and stick hose routing,” says Hochgürtel. The older configuration bent hydraulic fluid hoses over the top of the boom and stick; the new design runs the
hose routing along the side of the attachment in order to minimize bending, thereby reducing stress on the hose and giving it a longer life. Introduced to
the smaller-scale PC3000 and PC4000 in early 2014, the new hose routing will eventually extend to Komatsu’s entire range of excavators.
That includes the company’s largest hydraulic mining shovel, the PC8000, which has had a standard bucket capacity of 42 cubic metres at 1.8 tonnes per
cubic metre material density since 2004. Komatsu is not looking at increasing its shovel size at the moment, but Hochgürtel says Komatsu will evaluate the
possibility of increasing shovel capacity if the industry demands larger machines with regard to bucket size. To load its largest truck, the 960E, the
PC8000 takes an acceptable five loading passes.
The similar-sized R 9800 manufactured by Liebherr, with a starting capacity of 42 cubic metres, has seen a recent upgrade. Liebherr developed an add-on to
the R 9800 that improves its performance in backhoe configuration; the “high performance kit” includes a new bucket design with a capacity of 85 tonnes per
pass, while reducing the overall weight of the attachment.
“We particularly focus our development on the reduction of the total cost of ownership but also increased reliability,” says Swann Blaise, group leader of
the marketing department at Liebherr Mining Equipment.
On the five machines Liebherr has introduced in the past decade, this focus takes many forms: reliable electronics, easier troubleshooting, and the
development of electric-drive hydraulic excavators, which combines the precise controls of an electric drive with the flexible digging power of hydraulic
parts. The two largest machines, the R 9400 and the R 9800, both have electric versions available.
Although Liebherr took a cautious approach to growing capacity, Blaise believes mining shovels will continue to grow bigger in the coming years. And
indeed, prior to the mining sector’s most recent downturn, certain users were expressing a strong interest in getting more capacity out of their
excavators, according to Patrick Singleton, product manager for the 4800XPC, a new electric rope shovel design from Joy Global.
High-production, low-cost mining operations running 360-tonne haul trucks, like the oil sands and coal operations in Canada and the hard-rock copper mines
in South America, could see the economic benefits of getting down from four to three loading passes. At the same time, customers who already used Joy
Global’s 4100XPC shovel had specific requests for any larger electric mining shovels: higher capacity with the same footprint. “They wanted us to stay
within the same relative weight and ground-bearing pressure requirements,” explains Singleton.
The design of the 4800XPC is based on the 4100XPC AC, which has sold about 50 units since its introduction in 2010, but its dipper is at once larger and
lighter, with a capacity of around 65 to 70 cubic metres or 123 tonnes. In order to accomplish this, Joy Global improved load flow throughout the dipper
structure and used castings in certain areas for improved weight efficiency. An integral tooth base lip design borrowed and improved from hydraulic
excavators also helped lighten the dipper.
“There’s really a lot of subtlety and nuance within the design,” says Singleton. “The boom is 3.4 metres wide, which is considerably larger than our
existing booms from a width perspective, and that width allows us to offset the damaging effects of corner tooth loading, because that dipper lip is
getting wider. We’ve improved the overall strength of the dipper to allow for greater resistance to denting, and then we’re focusing a lot of effort into
the changes in the latch system.”
The 4800XPC also introduces the Adaptive Controls system, a set of control functions that optimizes the machine’s power usage during different phases of
the dig cycle. Although the operator largely maintains control over the machine, a set of algorithms quietly adjusts motor operation when certain tasks are
taking place in order to limit unproductive loads on the machine. For example, the “smart/dynamic crowd” function can prevent the boom from jacking or the
machine from tipping backward during a crowd motion, and it improves the dipper’s ability to penetrate hard rock. As an operator assist feature, Adaptive
Controls is a baby step towards autonomous operation of mining shovels.
Both Adaptive Controls and more structural innovations from the 4800XPC could be applied across the entire shovel product line, according to Singleton. The
question Joy Global now seeks to answer is: How do we get these other efficiencies onto the existing machines that we manufacture today?
Another unanswered question lies outside Joy Global’s power to answer: Who will be the first 4800XPC adopter?
“We’re still looking for the home for that first 4800,” says Singleton. “It’s not a situation where any customers are averse to the product at all. On the
contrary, there are some that are excited. But they’re fighting that uphill battle of capital expenditure in the current state of the mining industry.”