Hydraulic systems have been a mainstay of mining productivity for six decades, and suppliers are working on solutions that will allow them to keep pace with the industry’s electrification, decarbonization and energy-conservation efforts
By Russell A. Carter, Contributing Editor
The simplest dictionary definition of work – to set or keep something in motion – also accurately describes the role of hydraulics in heavy offroad machinery applications. For more than 60 years, miners have depended on hydraulic power to carry out the pushing, pulling, lifting and turning tasks involved in daily operations.
Traits such as overall ruggedness, high power density and the ability to handle variable shock loads have enabled hydraulics to massively expand their role in mining, growing from their initial implementation as a welcome replacement for clunky cable hoists and mechanical linkages on mobile equipment to inclusion as propulsion systems for the latest generation of bulldozers, pump motors, integral design elements in high-pressure grinding rolls, (HPGRs) and more.
The industry’s confidence in the technology is underlined by recent investment decisions; for example, Danfoss Power Systems’ acquisition of Eaton’s hydraulic business, or the announcement from a major supplier of hoses and fittings that it will invest $40 million to build a state-of-the-art industrial hydraulic hose production facility in Mexico mainly to support growing demand in North America. Recent McKinsey research shows that the global hydraulic pump market alone is valued at approximately $70 billion today and is projected to be worth $85 billion to $90 billion by 2025.
However, hydraulic systems also have significant limitations. They’re relatively inefficient, with as much as 40% of the energy they are capable of providing to a mobile machine lost through power-draining components and pressure drops at ports and metering valves. Most current hydraulic systems aren’t designed or optimized for energy recovery – a highly sought-after feature for effective operation of electrified fleets – and they’re generally ‘dumb,’ lacking the sensors and data collection capabilities of newer technologies. The industrial landscape is changing, and hydraulics technology will be challenged to match the pace of innovation in electrified power systems that can drastically reduce equipment noise, heat and emissions while providing advantages such as instant torque, reduced maintenance and smaller parts inventories.
In a 2022 McKinsey report titled Smart Fluid Hydraulics: Preparing for the Imminent Revolution in the Fluid Systems Industry, the authors identified some targets for OEMs seeking to establish a strategy to meet future trends in hydraulic applications, such as:
• Reassessing company strategy and technology road maps. “The introduction of smart fluid hydraulics entails a profound rethinking of the value chain for industry players. Equipment OEMs will need to assess their company strategies, define their technology road maps, and make a conscious decision on when to develop which type of smart fluid-hydraulics application,” according to the report.
• Considering integrated systems instead of single components. The most successful companies will offer a one-stop solution to customers and serve as an interface for single-component players.
• Focusing efforts on a limited number of relevant use cases. Companies will benefit from limiting the scope of their efforts rather than trying to target as many use cases as possible.
• Defining and building required future digital capabilities. Companies will need to build a strong, cross-functional internal team with an agile mindset and digital and software skills.
Recent conversations with heavy equipment OEMs and fluid-power system suppliers confirm they are acutely aware of the issues and challenges and are taking steps to meet evolving customer and market demands. For some, future strides might take the form of redesigns that shrink conventional hydraulic components, such as motors, while maintaining or increasing their power ratings. Others may focus on development of integrated systems that combine components that have typically been separate items, or on better power control and metering designs. And, for some, it will also include development of products such as compact, integrated electrohydraulic systems or a move toward electromechanical actuators that can provide precise control while eliminating maintenance and safety issues associated with conventional hydraulic cylinders, oil and hoses.
Although it’s safe to say that conventional hydraulic systems aren’t in immediate danger of extinction in offroad mobile or stationary plant equipment applications, the shifting focus of the mining industry from a strong preference for familiar, brute-force design solutions to more energy-efficient, sustainable choices brings with it the awareness that there’s room for improvement in typical hydraulics-powered use cases. With “greener” being the linchpin concept anchoring many corporate ESG and decarbonization programs, equipment selection decisions are increasingly influenced by a product’s perceived carbon footprint, energy efficiency, recyclability and overall environmental impact.
That places a triple burden on hydraulic system suppliers: First, how to manage product offerings in a market that is trending away from dependence on traditional diesel-powered solutions. Second, how to serve an industry that requires some of the largest, most powerful machinery on earth to do its job, but also has intense interest in technologies that offer lighter, more compact and potentially safer equipment. And third, how to ensure that their equipment can contribute to enterprise productivity without excessive resource consumption, environmental degradation or endangering a company’s social license to operate. E&MJ spoke with some of the industry’s most well-known suppliers and service companies to gauge the flow of this sector’s product development efforts.
Designing for the Lifecycle
Danfoss Power Solutions is a leading provider of mobile hydraulic and electrification products and solutions. Its product line and market reach expanded significantly after acquiring Eaton’s hydraulic business in 2021 for $3.3 billion. We asked Ben Hoxie, senior director-solutions, to comment on the company’s vision of the future role for conventional hydraulic systems in heavy machinery applications such as mining.
“We help equipment designers optimize their machines for the complete lifecycle,” he explained. “We see purchase cost, size, weight, life, robustness and reliability, maintenance, and energy consumption as key decision factors for machine builders. As the world works to decarbonize, some of the traditional machine architectures are changing, but not a need for operators, including in mining, to deliver in an ever more competitive world.
“We do see lots of opportunities for electromechanical actuation, particularly in applications with high impact from inadvertent oil leakage and/or high-intensity single actuation, both linear and rotary, such as our partnership with RISE Robotics or our Editron product offerings.
“That said, we do believe next-generation equipment will likely also have more advanced hydraulic solutions, particularly in machines and applications that need power density, impact resistance, ability to thrive in challenging environmental conditions, or cost-effective multi-axis distributed actuation.”
There are ways to make conventional hydraulic systems more efficient, he noted. “Danfoss offers many improvements to traditional hydraulic systems especially in the areas of efficiency, energy savings, and lower CO2 impact. Not just for battery electric vehicles, but also for low-carbon combustion machines as well. Many of today’s typical machine architectures were established when the price of fuel – both economic and environmental – was much less. During the design phase, machine builders have many options to improve the performance and energy intensity of their machines. Danfoss has a global network of expert application engineers to help machine designers understand the tradeoffs and optimize their machines.
“We’re helping improve machine performance by providing advanced valve and control systems that can enable a drilling machine to speed up through soft material and slow down at harder materials,” Hoxie continued. “This type of enhancement results in improved drilling time, machine and drill bit life, as well as energy consumption. Another example is our Digital Displacement Pump, an excellent solution for excavators that require many parallel actuation points to quickly move material. When coupled with our Editron electric motors and inverters, we have already shown a 25% reduction in battery requirements over a traditional excavator. “
Leif Bruhn, the company’s GM of Digital Displacement, provided more details about future applications. “We’re developing a larger Digital Displacement Pump (DDP1X0D) that can be applied to larger excavators. A single DDP1X0D unit applies to 20- to 40-ton class excavators, with typical engine power at 100-250 kW. Multiple parallel units with a gearbox, a solution that is commonly used in the industry, apply to excavators above 40 tons. We are working with OEMs on up to 90-ton class excavators, and we expect to apply DDP1X0 to even larger excavators after that.”
Higher Torque in Smaller Packages
Bosch Rexroth offers customers a wide range of hydraulics, along with electric drive and control technology, gear technology and linear motion and assembly technology. The company took the opportunity offered by a major mining trade show earlier this year to display fresh branding of its Hägglunds hydraulic motors and drives and highlight the operational characteristics that appeal to heavy equipment customers. These include:
Torque Control: Direct drives with low speed and high torque that can provide full torque from standstill, without time restrictions. Hägglunds hydraulic direct drives are designed to operate continuously throughout their power range up to their rated torque, from zero to full speed.
Start-Stop-Reverse: According to the company, Hägglunds hydraulic direct drives are able to switch automatically from driving to braking mode, and the direction of rotation can be switched quickly by changing the direction of the oil flow.
Shock Load Resistance: Its direct drive motors offer a solution without mechanical play and with a low moment of inertia so it can withstand vibrations, external shock loads and changing load directions.
Hägglunds released its Fusion Direct Hydraulic Drive last year, showcasing it as a unique system that “puts everything on the torque arm,” from the hydraulic motor and pumps to the cabinet that houses them, making high torque and superior reliability available from a single unit – in a remarkably small footprint. More recently, the company spotlighted its Quantum motor line at the 2023 International Fluid Power Exposition, pointing out that these direct drive units can be used in both mobile and fixed applications that demand high reliability with unique power density.
“The Hägglunds Quantum range rewrites the rules of power density, especially when it comes to efficiency at higher speeds,” said Wolfram Ulrich, vice president of sales for Hägglunds. “By stretching the limits so far beyond previous solutions, it introduces possibilities for greener operation, mobile applications and more.”
We asked Brian Howell, Hägglunds USA sales manager, to describe the types of applications for which Quantum motors are likely to be specified and what features or characteristics would make them a preferred choice for these applications.
“Quantum Power is well suited for applications that require high power and torque, such as large conveyors, crushers, sizers, agglomeration drums, and surface miners,” said Howell. “The features that make Quantum Power attractive for these applications are its power density, ability to offer unlimited start/stops, ability to withstand tough shock loads and provide high starting torque.
“Our R&D team optimized the casting of the Quantum Power to allow for high volume flow paths with reduced pressure drop to yield a highly efficient motor to direct drive a machine shaft. This means Quantum Power can produce 3 MW output power in a motor that weighs 2,100 kilograms.”
The new design doesn’t require specialized maintenance, according to Howell: “The most important maintenance practice is routine oil analysis to ensure the quality of the fluid meets the required specifications, and to perform semi-annual filter changes to keep the fluid clean. We also offer condition monitoring solutions that monitors the system performance in real-time and can alert the user or our technicians of potential issues, so we can proactively correct problems before they cause downtime, which is critical for mining operations.”
The company expects Quantum units to contribute to higher mining efficiency. “The benefit that Quantum Power brings is its high power to weight ratio, all while doing so without the need for a gear reducer,” Howell explained. “With its ability to provide direct-drive high-output torque at higher speeds, and yet deliver the same reliability, users can expect to see higher uptime with their machines. We see customers trying to scale operations to increase machine performance and minimize their use of combustion engine-powered equipment to transfer or transport material from one location to another in a mine via large conveyors. Quantum Power is up to this task as its size range fits well to machines that can move materials more efficiently in the mine site.”
An important benefit offered by Quantum Power is the ability to handle high shock loads in applications like sizers, crushers, and surface miners: Where a conventional electro-mechanical drive is typically over-dimensioned to handle the shocks and peak loads that these machines see in operation, Quantum Power “takes this in stride and continues to provide reliable performance to meet customer requirements,” said Howell. “Like all Hägglunds direct drive motors, Quantum Power can deliver maximum torque down to zero rpm, which allows users to keep operations running even in overload conditions or if they need to slow the process down due to limitations in other equipment or processes.”
Fluid power systems are used throughout the entire mining sequence – and for good reason: they’re designed and engineered for longevity and the ability to handle massive loads at variable speeds. That’s also a recipe for potential unscheduled downtime, particularly when those mechanical demands are coupled with environmental conditions such as extreme temperatures, dust or corrosive substances.
Motion Industries (Motion) is a leading North American supplier of industrial parts and solutions that serves both the MRO (maintenance repair and operating) replacement parts and OEM markets. The company launched its fluid power business brand, Mi Fluid Power Solutions, in mid 2022 as a full-service provider of fluid power, integrated electronic controls and electro-mechanical technologies for industrial and mobile equipment. As a supplier with insight into the full fluid-power product usage spectrum, E&MJ asked Scott Smith, division manager–West Shops, at Motion to comment on common maintenance and equipment failure problems encountered by company technicians, and on the demands that future performance goals might place on fluid power systems.
“With hard rock mining equipment, two most common problems we see are system heat and oil cleanliness, causing reduced component life and machine downtime,” said Smith.
Like many hydraulic systems, hard rock mining equipment is operated most often at the design limits of the system, including speed, torque, power and pressure, on a 24/7 schedule, he explained. “Machine conditions are tough, causing the systems’ high-pressure spikes and continuous impulses. All these factors add up to high heat loads that can devastate oil film strength, ultimately reducing component life. We often see hydraulic systems where the cooling system has been neglected, which lessens or eliminates cooling capacity.”
According to Smith, contamination control must be a priority in investment and maintenance focus for hard rock mining equipment. “Oil cleanliness standards must be established and followed to maximize system hygiene, improve uptime and increase component life. These standards should include ISO cleanliness code targets for system components and filter element life indicators that are monitored and utilized rather than ignored. A stringent oil sampling program is also necessary to fully understand the payback of your filtration investment.
He recommended a set of best practices for heat and contamination control in hydraulic systems. This includes:
♣ Ensuring all heat monitoring sensors work and cooling fans operate when called upon.
♣ Ensuring air cooling fins are clean of waste and debris, maximizing the efficiency of the cooling air.
♣ Installing dust filters in front of air-cooling fins to manage debris buildup.
♣ Moving to a synthetic oil with a higher viscosity to reduce oil breakdown and increase film strength.
♣ Adding reservoir flushing systems for more oil-cooling capacity.
♣ Implementing ISO cleanliness code standards to match the component manufacturers’ specifications.
♣ Installing delta-P indicators on return and pressure filters to maximize element life.
♣ Using element condition indication to schedule element replacement before it goes to bypass.
♣ Using synthetic, beta-rated single-pass elements in all hydraulic filtration other than kidney loop systems.
♣ In very critical systems, installing real-time inline condition monitoring (ICM) to observe oil cleanliness with ISO particulate contamination, water and temperature level displays.
Smith predicted that, as the mobile equipment industry migrates to more battery-powered systems overall, the hydraulic sector will need to respond with higher power-to-weight efficiencies. “We have witnessed many changes in the past 15 years, with mobile hydraulics moving from 200 to 350 bar systems and now more than 420 bar systems,” he noted.
“In addition to higher pressures, we will see more changes in materials used in hydraulic components, such as carbon fiber and other advanced materials providing very high strength with reduced weights. Reservoir sizes can also be reduced when the circulating volume of the system is decreased, saving weight.
“As system pressures climb and reservoir sizes decrease, we will see more investment in hydraulic cooling system components,” Smith explained. “To achieve some of the cooling deltas needed in these systems, ambient air-cooling deltas are no longer sufficient. To reach the higher-cooling deltas, components such as refrigerated coolers need to be considered.
“Pressure and temperature increases will affect oil viscosity and film strength, which are vital to component life,” he continued. “The type, grade and maintenance of oils used will be critical to component life and system efficiency. The ISO filtration levels will need to be increased, as higher-pressure components are more susceptible to internal component wear.
“With weight reduction and hydraulic system efficiency as a focus in mobile machine design, we will see more hydraulic auxiliary functions move to electric linear actuators. Improvements in 12- and 24-VDC electric linear actuators, including power, stroke length, and ruggedness, often make them a better choice over traditional hydraulic actuators.
Actually, Tier 4 engine mandates in mobile equipment have already driven some of the above, according to Smith. However, size and weight reductions due to battery power will continue to pressure hydraulic components and system manufacturers to improve power-to-weight ratios.