Fuelling productivity in quarrying equipment
By Steve Skinner09 November 2010
The longevity of quarries places specific demands on the equipment used especially in relation to fuel efficiency and overall lifetime costs.
Regional manager at Heidelberg Cement's Jehander quarry in Kållered, Sweden, Niklas Osvaldsson speaks for many quarry operators when he says that a major cost is fuel. "Fuel costs are increasing, so consumption is a big issue for us and we are always trying to find ways to reduce our usage," he told iC.
The quarry is currently testing a Volvo L180F wheeled loader equipped with optishift and reverse by braking (RBB), two new systems developed by Volvo to cut fuel consumption by up to +15%.
Optishift uses a new torque convertor with a free wheel stator that can be locked to eliminate energy loses. The system is suited to load and carry applications and the lock-up feature also improves hill climbing performance and therefore productivity.
The RBB feature applies the brake to stop the wheeled loader when changing from reverse to forward motion. Volvo spokesman Arvid Rinaldo said, "Many operators traditionally changed gear and used engine power via the torque convertor to switch from reverse to forward motion.
"What RBB does is automatically apply the brake when a forward gear is selected while the wheeled loader is still travelling backwards. Essentially, it brings the machine to a proper and controlled halt before enabling forward acceleration.
"This saves fuel, improves operator comfort and produces less stress on the torque convertor, which in turn lengthens the life of the transmission," he said.
Optishift and RBB are currently available on Volvo's L150F, L180F and L220F wheeled loaders but Mr Rinaldo said the systems will be fitted as standard on all new generation wheeled loaders.
Caterpillar's application specialist for quarrying, Vincent Migeotte shares in the belief that efficiency is the dynamic behind developments in the sector. "The main driver for the interim update of our 988H wheeled loader was to lower operating costs and specifically fuel consumption," he told iC.
The wheeled loader now features a new hydraulic system featuring proportional flow control to increase efficiency. There is also a new bucket with a wider opening and a longer floor.
"This bucket has greater material retention than the earlier version. In back-to-back tests, when measured as litres of fuel used to move one tonne of material, it gave us up to +10% better fuel efficiency. If with every cycle an operator can get easier penetration and load +10% more material, the combination offers a real improvement in productivity," said Mr Migeotte.
Caterpillar introduced its new quarry body for rigid haul trucks at Bauma. The new body has led to a 1 m3 increase in capacity with the company's 36 and 45 tonne 770 and 772 models and a 1.5 m3 increase with its 64 tonne 775 model.
Mr Migeotte told iC, "We found for quarrying applications, and particularly with limestone and gravels, that our customers wanted a single flat floor body with no liner, but a good reinforced body. We've met this demand with the new quarry body that's constructed from SSAB's 25 mm thick Hardox steel. This has helped us to optimise the maximum payload of the trucks to gain efficiency. It also lends itself to easier dealer management as there are no individual liner specifications to stock."
Also at Bauma, Caterpillar unveiled its 336E excavator, the company's first Tier 4 Interim emissions compliant unit. Mr Migeotte said, "In developing this excavator, we concentrated on reliability to make sure the systems and design worked well.
"Having now conducted over 10000 hours of field tests across different applications in different parts of the world we have confirmed that our Tier 4 Interim system doesn't impact on the normal operation of the machine and that, depending on application, we have gained +5% improved fuel efficiency," he said.
Hyundai marketing manager Michel de Weert told iC that through the launch of its 9 Series equipment, the company had redesigned the hydraulic systems of its 50 tonne 520LC-9 excavator and its 5 m3 capacity HL770-9 wheeled loader to enhance performance, smoothness of operation, operator comfort and fuel efficiency.
"The design of both machines was built around an improved relationship between engine and hydraulics to offer more precise control, reduced fuel consumption and better net use of the engine output," he said.
Both machines feature enlarged operator cabs with improved visibility and more adjustable controls to aid operator comfort.
For Hitachi, wheeled loaders form a key part of the company's business strategy. "The alliance between Hitachi, Kawasaki and TCM has enabled us to further develop and expand the ZW Series of wheeled loaders," said manager of international sales for heavy and mining equipment, Greg Smith.
"The introduction of the 26 tonne ZW330, 31 tonne ZW370 and 46 tonne ZW550 is testament to what can be achieved through the sharing of technology and information."
The new wheeled loaders have been developed to achieve higher productivity while attaining similar fuel consumption to the models they are replacing according to Mr Smith. "More customers are focussing on the total cost of ownership, which means we have to continually improve every parameter that affects performance," he said.
Over the past three years, Caterpillar has equipped all of its machines with product link. "This means over 50000 machines are now sending information back to their owners, to dealers and to ourselves about geographical position, fuel consumption, idling time and other operational information," said Mr Migeotte.
"This is a big source of information for us that has already led to developments in our equipment, such as the auto-shutdown feature, which we launched at Bauma and that is already a standard feature on the 988H wheeled loader."
With the system, if a machine is left idling for more than a predetermined time agreed by the operator and dealer and it's in a safe position, then it automatically shuts down.
"With product link we saw that machines in quarries were idling for up to 40% of the time, which is a waste of both fuel and accumulated hours on the machine. Just by shutting down the engine we can delay service intervals and reduce machine hours, which is of value when it comes to resale," he said.
Bell Equipment launched its Fleetmatic software back in 2004, which marries machine performance with production to establish precise business parameters, all transmitted over the Iridium satellite system so there is full global coverage. "This system makes more information available than ever before and has shown us that our articulated dump trucks (ADTs), for example, are still spending up to 60% of the time idling," said sales and marketing manager Josh Foster.
With this information, Bell developed its auto idle and auto shutdown systems, which are now standard features across the company's range of ADTs. With time delays set by quarry managers, auto idle sees the machine switched to low rpm mode, which then progresses to auto shutdown if there's continued inactivity.
"Bell's design philosophy is linked to fuel efficiency. We have taken many operator decisions out of play so that equipment is operated more precisely and efficiently," said Mr Foster.
The company's ADTs feature electronic systems such as inclinometers and on-board weighing systems that combine to increase productivity, safety and efficiency. "ADTs are fairly easy to tip over because, due to the articulation, an operator cannot feel if the rear section is lifted on one side," said Mr Foster.
"With the inclinometer, we have developed an automatic safety stop that prevents tipping if the rear of the unit is off centre. The operator display will highlight a loading area problem and the operator can then reposition the truck for level tipping."
The on-board weighing systems aid operators, both in terms of productivity and efficiency. Mr Foster told iC, "The obvious advantage of on-board weighing is that an operator knows when he has the optimum load.
"Equally, the system means the machine knows if it's loaded or not and therefore automatically selects the appropriate transmission setting. In combination with the inclinometers, the truck can also sense if it is climbing or on level ground, and again can automatically select the optimum transmission setting," he said.
"In quarrying, it's all about cost per tonne, and I would say Bell machines are more intuitive, which aids precision and therefore efficiency."
In addition to the fuel savings that can be found through the correct choice of equipment, proper use of machines can also have a drastic impact on a quarry's fuel consumption. Caterpillar's Eco-operator training, which is available through the company's dealers or directly with Caterpillar, teaches operators how to use machines properly and more efficiently.
Mr Migeotte told iC, "We have found that after a one day training course, operators are generally burning -15% less fuel while maintaining exactly the same levels of production."
Volvo too has its own Eco Operator programme, which has seen operators cut fuel consumption by between -5% and -25%. Mr Osvaldsson of the Jehander quarry said, "Volvo Eco Operator training is carried out on-site so it's efficient and close to real production needs. All of our operators will be attending training this year."
Volvo Eco Operator training covers aspects such as correct tyre inflation, gentle use of the accelerator, working at reduced rpm, switching off instead of idling, keeping the site free of obstacles, choosing the right equipment and working in cooperation to optimise machine interaction.
Due to the longevity of most quarries, the demands in this sector are unique. As Mr Migeotte told iC, "The beauty of a quarry is that it's there for many years. It involves day-to-day maintenance and operation as the operator is not trying to get the maximum out in just one hour. As such, safety and consistency are key and the challenge is to have properly configured equipment and harmony between processes to attain optimal efficiency and productivity."