Minesite vehicles have progressed and evolved as the need for bigger, safer and environmentally friendly trucks has grown.
Before mechanisation, the mined material was shovelled by hand into skips and pulled to the main road by horses. It was not until the 1950s that serviceable mine trucks were being utilised across Australia.
Minesite vehicles have progressed and evolved significantly over the last 100 years from horses pulling a tonne of ore in a cart to haul trucks with a payload capacity of 360 tonnes.
Today it seems size does matter. Large bucket wheel excavators can be 100m tall and 200m long.
With the demand ramping up from the off-shore markets including China and India, mining companies are placing a greater emphasis on improved efficiencies, essentially doing more with less investment.
According to Caterpillar’s global mining president Chris Curfman, today’s minesite vehicles are significantly advanced in comparison to their predecessors.
They have the ability to collect and interpret advanced information, can address sustainable development issues while also being safe, reliable and operator friendly.
“In the pursuit of lowest total cost of ownership, the primary purchasing criteria for mining machines, mining customers and suppliers have arrived simultaneously at essentially the same conclusion, although probably using different paths,” Curfman told Australian Mining.
“The relationship between the customer and the supplier had to evolve from a traditional focus on initial price for equipment acquisitions. It needed to evolve to an interdependent relationship focused on common goals and objectives that support attaining the lowest total cost of ownership while addressing the broader issues of sustainability, safety and leveraged growth,” he said.
Early developments
The first excavator was a steam powered shovel, manufactured in the United States of America in 1835.
However, it wasn’t until more than a century later that excavators replaced horses on Australian minesites.
The first modern form of hydraulic excavator was conceived during the 1940s following the mechanical engineering revolution.
The original wheel loader was conceived in the agricultural industry in the 1920s when tractors were fitted with a loading shovel. However, the first self contained two-wheel drive, rubber tyre wheeled loader was introduced much later in 1939.
Early engineering designs aimed to produce a face shovel bucket attachment to a machine that could re-handle light agricultural materials.
Such attachments are still available today. However, the ‘front-end’ machine became much sturdier and suitable for carrying heavier payloads.
During World War II there was a scarcity of labourers on minesites, which in turn, led to further development in minesite vehicles.
In an attempt to minimise the impact of having less workers on-site, manufacturing companies started developing machines that could complete the work of several miners.
Following World War II, there was an upsurge in infrastructure projects. This provided mobile equipment manufacturers with an incentive to further develop off-highway trucks and the equipment to load them.
As mining became one of Australia’s greatest resources, and demand for minerals surged, the need for scrapers, graders, track and wheel dozers also surged.
The world’s first articulated (ADT) dump truck was developed by Volvo in 1957 and was called the ‘Moon Rocket’.
The concept underlying the design of ADT’s is the use of a connection between the front and rear frame and an all wheel (four or six) drive.
By the late 1950s most of the horses were gone from the mines and nearly all fixed boom steam shovels had been replaced by diesel and electric-powered shovels and draglines.
The majority of these still had low dipper or bucket capacity, but new shovels and dragline excavators were capable of moving ever-larger quantities of overburden and coal.
Larger shovels and bigger trucks meant the productivity of surface mining continued to rise.
Western Australia School of Mines research associate Ray Hardy told Australian Mining that market demand was met by response from original equipment manufacturers with mining trucks and matching loading equipment of ever increasing scale and capacity.
“Minesite vehicle manufacturers continue to frequently upgrade the range of earthmoving equipment,” he said.
“Today, minesite vehicles are expected to have fuel efficient engines, low profile tyres with longer tyre life potential and mine specific design bodies.”
Since the 1950s, there has been constant development in rope shovels.
In the 1960s hydraulic excavators, both backhoes and shovels, were introduced.
The earliest large mining hydraulic shovels and backhoes were introduced to Australia at Weipa in North Queensland in about 1974.
In 1976 85-ton trucks replaced 40 tonne mining trucks.
An alternative future
Recent trends indicate that mining companies want technologically advanced, bigger, energy efficient, safer and cost effective earthmoving machines.
One cost effective technique employed by manufacturers is parts commonality.
Tyres, spare parts, and service support continues to be a critical issue.
The importance of these issues is fundamental for the earthmoving equipment industry at the moment as the boom in mining in Australia and in China and India requires quicker service, efficiency in repairs and maintenance and up to date equipment to keep up with the high workloads.
Thanks to these markets, there continues to be an economic push to increase the productivity of mobile material handling equipment used in open-pit mines. This includes the largest electrical machines: excavators and haul trucks.
Existing DC drive systems used on this type of equipment are a mature technology.
They have no further economic potential to accommodate larger equipment because of the high maintenance costs and the trade-off between power, speed and space limitations of their DC traction motors.
In recent years the large scale introduction of AC drives in the rail transportation sector has led to the development of compact, powerful and rugged AC inverter drives specifically adapted to the mining market.
The major advantage of AC drives stems from the squirrel cage induction motor which eliminates the DC commutator.
This leads directly to higher speed, increased power density, higher reliability, greater efficiency and lower maintenance of the traction motors.
In the context of excavators and haul trucks, additional benefits driving the move to AC are increased power density, increased reliability and lower cost inverters using active front-end technology that improves compatibility with the mine power grid and improved dynamic response.
According to Curfman, there has been a significant advance in AC drive technology in the mining industry.
“With recent advances in AC drive technology, it is appropriate to make electric drive available as a complement to the pre-existing mechanical drive,” Curfman said.
In the future Curfman believes AC drive off-highway trucks will be readily available.
“AC drive system technology is still in the development phase. To ensure reliability when the technology does finally make its way onto the market, AC drive trucks will be utilised for testing purposes,” he said.
Effective control
Other recent developments include the introduction of simplified control systems.
“Mining machines continue to evolve and deliver greater productivity, reliability and durability,” Curfman said.
“The current use of electronic control systems enables earthmoving manufacturers to better integrate each of the power train components for more efficient operation and longer life.
“The components of a truck or loader must operate optimally with other components to deliver lowest cost per tonne. Electronic controls and monitoring help achieve that goal,” he said.
In the electronic control system, a dozen levers and a steering wheel is replaced by two joysticks providing easy vehicle manoeuvrability.
However, even with the implementation of electronic control systems, getting behind the wheel for the first time can be a daunting experience for anyone, especially when that vehicle is worth millions of dollars.
Ten years ago, Immersive Technologies saw the need for a sophisticated training tool to bridge this gap between the classroom and equipment operation.
The company developed the first commercial mining simulator, allowing new and experienced operators to train in a virtual mine site environment before entering the production circuit.
The simulators allow trainees to become comfortable with the equipment controls, operating techniques and site proceedures.
According to the company, minesites have slashed average monthly incidences of engine over speed by 69% and haulage brake failures by 15%.
Minimising accidents
According to Tony Johnston from Liebherr, arguably the biggest development in minesite vehicles has been the implementation of hydraulic engine systems.
"These systems perform effectively, so production is higher,” Johnston told Australian Mining.
"Today, there is a greater focus on productivity. So in response, companies have improved operator comfort by redesigning the cabs, belts and everything in between.”
Another Milestone has been the sheer size of minesite vehicles.
“Over the decades, minesite vehicles have grown ten-fold,” Johnston said.
The 797 from Caterpillar is the world’s largest off-highway truck. It has a payload capacity of 360 Tonne and stands at 7m tall and 16 m long.
However, as earthmoving vehicles grow, so too do the problems associated with them.
Today’s mine haul trucks are massive vehicles in which drivers have limited vision and cannot see anything within around 30 metres.
If a smaller vehicle on the mine site gets in the way of one of these monsters, the consequences can be dire.
New technology includes additional video cameras that automatically display a detected vehicle on the monitor, along with its speed and position.
This new technology not only alerts the driver if a hidden object is moving relative to the mine haul truck, it alerts them as to what direction it is moving, what its rate of change is and whether a collision could occur.
The future is bright
Increased demand from world markets has provided mining companies with a much needed reason to continue to push for technological advancements in minesite vehicles. However, it is not just the engines and operator comfort that has improved and developed.
The CSIRO has created a novel haul truck measurement system that has been developed using scanner laser technology.
The main features of the system are the ability to measure the in-situ volume of the haul truck load, to perform the measurement while the truck is moving, to calculate the volume automatically, and (when combined with a weight measurement) to provide a bulk density measurement.
According to Bob Chamberlain from the CSIRO, the commercialisation phase is complete and the product is now being marketed.
It seems the future is bright for minesite vehicles.
New AC drive technology will facilitate dramatic improvements in production rates, reliability, power grid compatibility, efficiency, maintenance cost, and system intelligence.
Furthermore, ongoing improvements in minesite vehicle technology will no doubt warrant larger earthmoving vehicles with greater load capacity to ramp up productivity.
With the mining industry brining in the big bucks, there is a plethora of available resources that can go towards further technological investigations, developments and improvements.
Australian Mining thanks Western Australia School of Mines research associate Ray Hardy for his assistance in research for this article.
Ray Hardy
Research associate
Western Australia School of Mines
rayhardy2@bigpond.com
Tony Johnston
Liebherr
www.liebherr.com/me
Chris Curfman
President
Caterpillar Global Mining
MSprouls@aol.com
www.cat.com
Bob Chamberlain
Marketing & Communication Manager
Minerals Down Under National Research Flagship
CSIRO
Bob.Chamberlain@csiro.au
www.csiro.au/org
Immersive Technologies
Support@ImmersiveTechnologies.com
www.immersivetechnologies.com