Caterpillar’s latest innovations in electric drive wheel loaders and articulated trucks have recently been put to work at a showcase for the extractive and construction sectors in Western Australia. Damian Christie reports.
On 31 October, 2019, dealers and key clients ventured to Quarry Farm, 56km south of Perth, for Caterpillar’s Load and Haul Event where the original equipment manufacturer presented the latest developments in its wheel loaders and articulated trucks and a range of other machinery.
Caterpillar’s new electric drive (XE) wheel loader range was intended as the centrepiece of the event. The Cat 988K XE and 972M XE loaders worked in concert with the diesel-operated 986K aggregate handler, the 740 GC and 745 articulated dump trucks (ADTs) and the mine-spec 6015B excavator. There was also a presentation of the Piacentini Panther low loader, which was designed by Bunbury-based contractor Piacentini & Son. It has been developed to improve safety and efficiency for the loading and transportation of heavy equipment around mine sites – and to prove its mettle, the 740 ADT towed the low loader, with the 6015B on its back, around the quarry.
The electric drive transmission replacement technology was first introduced by Caterpillar in 2008 – on a track-type D7E tractor. The XE powertrain in the decade since has been subsequently developed for three of Cat’s product families with different designs. This included the 2012 launch of the XE concept on the 966K and 972K medium wheel loaders which had continuously variable transmission and virtual or electronic gear.
The XE technology is intended to lower average fuel consumption by up to 25 per cent on machines with traditional torque converters, as well as offering simplified operations and high performance at all speeds. As Ayden Piri, the Asia-Pacific industry specialist and account manager for Caterpillar’s Global Construction and Infrastructure (GCI) division, told Quarry: “The XE design uses electric components with electronic control systems to reduce fuel burn and increase productivity and overall efficiency.”
According to Caterpillar, the XE machines have been rigorously tested in-house (sometimes against their predecessors and against competitive brands) and field-proven to ensure they are economical and efficient.
ELECTRIC DRIVE LOADERS
The 988K XE – which was first launched at bauma 2019 in Munich, Germany – is intended for demanding job sites which value fuel efficiency. It is therefore expected to be up to 25 per cent more productive than the conventional, diesel-run 988K (whose forebears span 50 years), as well as up to 49 per cent more efficient at the quarry face. Yet, despite the change in powertrain, the 988K’s customary C18 ACERT engine, mechanical dropbox, driveline and axles remain a staple of the electric machine for trouble-free operation.
The loader offers a single speed range, which means it can efficiently operate without the need for gear shifts.
New virtual gears help to control machine ground speed and deliver smooth direction shifts. Further, Caterpillar production studies report this new loader can deliver up to 10 per cent more productivity in load and haul applications. It is performance matched to efficiently load the Cat larger rigid trucks, including the 38-tonne 770G (three passes), the 46-tonne 772 (four passes), the 55-tonne 773G (five passes) and the 64-tonne 775G (six passes). Its standard and rated payload reaches 11.3 tonnes when working with face material and 14.5 tonnes with loose material. Its bucket capacities cover 4.7m3 to 13m3.
The 988K XE is also equipped with switched reluctance (SR) technology. Piri explained that the SR system runs “by reluctance torque. Unlike the common DC system, power is delivered to the windings in the stator (case) rather than by the rotor. This greatly simplifies mechanical design as power does not have to be delivered to a moving part. This means less heat, less wear and smoother power transmission”.
The loader’s XE technology is also said to lower overall maintenance costs, with extended oil change intervals of 2000 hours, requiring 40 per cent less powertrain oil. It offers increased engine life expectancy by up to 3500 hours, extending time between powertrain rebuilds.
“The 988K is considered a large wheel loader,” Piri explained. “With size comes capacity and productivity expectations. Obviously larger units will be best for a wide range of work from face loading to load and carry operations.”
While some of the 988K XE’s diesel-run predecessors have over many years worked in quarrying applications, the medium size 966M XE and the new 972M XE loaders are more specifically designed for aggregates, sand and gravel, concrete batching, and construction applications. They are also suitable for poor underfoot conditions and steep gradients which make traction difficult, thanks to what Piri described as “on the go disc-type differential locks”.
“These models come standard with front axle differential locks which are manually activated by a switch on the cab floor,” Piri explained. “Optional fully automatic front and rear axle differential locks operate by measuring differences in wheel speeds and require no operator intervention to activate. These disc-type differential locks reduce tyre scuffing compared to other traction aids, further reducing operating costs for customers.
“The axles contribute to lower fuel consumption due to lower oil levels, reducing churning losses from rotating components,” he continued. “They also have new external caliper disc parking brakes mounted to the input of the front axles. Caliper parking brakes have a higher capacity than the drum brakes used on the 966K and 972K. Since they are external, they don’t have the inefficiencies of enclosed wet parking brakes due to brake discs running in oil, nor is there any oil to change. The results are reduced fuel and maintenance costs. External caliper brakes are easily accessible for inspection and service.”
The M-series XE loaders’ hydraulic systems are a mono-block design with integrated ride control systems that have become standard in the regular M-series loaders. The ride control systems use two accumulators, which enable more efficiency and productivity over a greater payload range.
“Hydraulic system components on the 966M XE and 972M XE are protected by full flow and kidney-loop filtration,” Piri explained. “A filter in the hydraulic tank return line filters all of the oil returning to the tank. There is also a case drain screen for additional protection and finally, a separate kidney-loop filter with a finer micron rating continuously filters smaller particles out of the system.
“This multi-level design ensures the hydraulic oil is clean and thoroughly protects the rest of the hydraulic system from contamination. A new thermal bypass valve has been added to improve hydraulic system warm-up.
“On the 988K XE, we have increased efficiency through our Positive Flow Control (PFC) hydraulic system. PFC has concurrent pump and valve control. By optimising pump control, the hydraulic oil flow is proportionate to implement lever movement.”
In the M-series XE loaders, new implement pumps with larger displacements for increased hydraulic flow at lower engine revolutions per minute continuously and automatically balance hydraulic loads with the machine performance stipulated by the operator. The pumps save fuel and improve engine response.
The M-series XE loaders, the 988K XE and the 986K loaders are all equipped with technology solutions to increase operating efficiency and vehicle uptime, including the Cat Production Measurement (CPM) program, which offers advanced weighing modes that assist the operator with payload accuracy and increased loading cycle speed.
“The system automatically weighs each bucket load as the load is raised without any need for the operator to hesitate or stop the lift cycle which can be done while travelling,” Chris Barrett, the Caterpillar technology specialist for the company’s GCI division, told Quarry.
“Some exclusive features that help operators increase cycle times are the ‘tip off’ and ‘low light weighing’. Low lift weighing provides an estimate of bucket payload quickly without lifting through the entire weight range. Tip-off then provides adjusted weights in real time, which allows operators to make final pass load adjustments either at the truck or the stockpile. Both of these features increase cycle time.”
The CPM can be viewed on a multi-purpose colour touchscreen in the cab. The intuitive navigation with in-language text encourages operators to adjust their machine operating parameters and monitor machine condition from the cab.
The 988K XE and the 986K are also equipped with remote monitoring systems via the standard Cat Product Link and Vision Link programs to keep personnel informed about critical machine operating data, eg fuel usage, payload summaries, service reminders, faults, and productivity reports.
The on-board Vital Information Management System (VIMS) also alerts the loader operator to real time fuel consumption and efficiency. The operator can also utilise an optional tyre pressure monitoring system via the VIMS platform. The Cat Connect Solutions software on the M-series electric drive loaders perform similar functions to the Cat Product Link and CPM on the 988K XE and the 986K.
Barrett said these programs provide “comprehensive information” for producers to manage and optimise their fleets.
“Cat Productivity provides precise payload, location and time details while developing cycle segmentation data for analysis. It tracks daily productivity with quick access to truck stored weights, loads and cycle counts, material movement, and daily totals. It enables tracking of fuel costs and machine hours and enables live payload data for analysis. This is ideal for comparing productivity between shifts.
“The dashboards enable an easy review of high idle time and encourage data-based decisions to determine optimum distances of cycle segments and fleet deployment based on hourly utilisation updates.”
The 986K loader has the potential for fuel economy and improved efficiency. A complement to the conventional 988K loader and a replacement for the legacy 988F model, the 986K’s aggregate handler configuration features an 8.3m3 bucket and additional counterweight for higher volume loading of aggregates. It is well matched for loading 36- to 53-tonne articulated and rigid trucks, including the Cat 740 GC and 745 (four passes), the 770 (four passes), the 772 (five passes) and the 773 (six passes), especially with its high-lift configuration.
The 986K’s Z-bar loader linkage provides visibility to the bucket edges and work area and delivers aggressive digging capabilities and high breakout forces.
The senior quarry specialist for Caterpillar’s GCI division, Felice Stocco, told Quarry the 986K was a suitable replacement for the 988F legacy loader. “The capacity and the production of the primary hopper determines the size of the loading tool and machine size,” he said
“The 986K shares the same proven legacy design of the 988F. This loader carries over a common linkage layout while updating parts for improved service and commonality across the wheel loader family. The 988F linkage had a reputation of being an outstanding digging machine. This is why we didn’t feel the need to change the layout or the kinematics. This makes it ideal as a 988F replacement and where high production and portability is valued. So, all you are doing is to replacing an old model with the latest product that comes with lower fuel burn, more productivity, more comfort and better safety features.”
As discussed, the 40-tonne Cat 740 GC and 745 trucks complement the 986K, 966M XE and 972M XE loaders. According to Piri, both articulated truck models feature a re-engineered cab design for enhanced comfort and ease of operation. They include new controls, transmission-protection features, hoist-assist systems, Advanced Automatic Traction Control (AATC) systems, stability-assist machine rollover warning systems, and a fuel-saving ECO mode.
Piri said the 740 GC and the 745 are the largest ADTs available from Caterpillar and ideal for quarry operators. “The 745 is designed to match heavy applications and the new 740 GC is aimed particularly at the life cycle value customer who requires a reliable, cost-efficient 40-tonne class truck – without the need for the ‘out and out’ productivity of the larger 745.
“The new 740 GC is based on the 735C and 745 platforms, with adjustments to systems to create a genuine 40-tonne articulated truck with all the durability expected of a Cat ADT.”
Both vehicles are equipped with the fully AATC system for stability on steep gradients. Piri said that while the AATC on the articulated trucks works on the same principle as the differential locks on the medium size XE loaders, the key difference is it is fully electronic.
“Proactive application of the inter- and cross-axle differential locks is ‘on the go’ and fully automatic,” Piri said. “The operator does not have to think about when and where to engage either diff lock. Sensors monitor the machine and wheel speeds, enabling instant response in high rolling resistance conditions. Operation is seamless and smooth, eliminating wheel slippage for maximum traction and therefore productivity. Clutches are automatically disengaged when ground conditions allow, maximising efficiency when steering or when on uneven ground. AATC reduces tyre and driveline abuse, eliminating lost machine efficiencies caused by improper manual operation of the differential clutches and reducing the cost of premature tyre replacement.”
Both vehicles are fitted with Cat CX38B high density power shift transmission and automatic retarding control systems. A terrain-based, throttle-smoothing system prevents throttle input surges as the ADT travels over extremely rough ground, thereby enabling the operator to keep steady pressure on the accelerator pedal. Hill assist systems facilitate efficient stopping and starting on grades, reducing the risk of rollbacks. The two vehicles also incorporate a “wait brake”, which temporarily applies the service brakes during pauses in the work cycle, combined transmission and hoist lever systems to minimise operator effort in body hoisting functions, and directional gear shifting protection to bring the truck to a safe stop.
The cabs of the 740 GC and the 745 are also fitted with new external “spinal” rollover protection systems (ROPS), which comprise bonded rear quarter glass to give the operator enhanced visibility of the job site (without the inconvenience of a structural pillar), as well as a host of other safety features, eg automatic climate control systems and a “wake-up” feature which initiates displays and external access lights whenever the door is opened. The Cat Detect with Stability Assist system, which monitors the working angle of the tractor, body and grade, will audibly and visibly caution the operator if the vehicle is at risk of tipping over.
Caterpillar’s Link and CPM technologies are also fitted to the ADTs as standard, and buyers have the option of fitting Cat Connect PAYLOAD technology for the optimisation of operations and jobsite efficiency. Cat Connect PAYLOAD calculates the vehicle’s payload via sensors on the walking beam suspension and includes load status lights on all four corners of the cab roof to enhance the operator’s view.
When it comes to price point and return on investment, Piri said that producers should consult the Cat dealer network around Australia for the best outcome.
“Caterpillar’s dealership network is best positioned to provide adequate information about price, availability, total cost of ownership and return on investment,” he said.
He expressed confidence that the XE range of loaders will make an impact in the Australian extractive industry market. “XE products move more material with less fuel and less time spent on the jobsite,” he said. “These gains can be easily measured in a variety of applications.”
Felice Stocco echoed Piri when he was asked to dispense some advice for quarrying producers looking to buy or upgrade their earthmoving plant and equipment. “Lowering total cost of ownership is an objective all are trying to achieve, therefore optimising the fleet to match productivity is a good starting point,” Stocco said. “Caterpillar and Cat dealers’ quarry experts would be available to visit your site anywhere in the country to provide you with customised solutions and tailored advice.”