From bearings that can fit comfortably in the palm of your hand to gearsets that weigh over 100 tons, mechanical components used in mining are being designed to handle increasingly heavier loads and longer duty cycles. (Photo: Kumera Corp.)

Mechanical drive systems are essential for turning energy into productivity. E&MJ samples the newest technology, features and services offered to keep the machines running.

By Russell A. Carter, Contributing Editor

As one of the oldest of the basic industries, mining has historically labored under the burden of public perception that it’s a dirty, noisy business that involves a lot of large, powerful equipment. While that’s actually a fairly accurate characterization of the industry, it doesn’t take into account the expanding universe of technological improvements adopted by today’s mine operators, particularly in light of the industry’s growing focus on digitalization, automation and electrification. 

But because of that emphasis on higher tech, it’s also easy to overlook the fact that very little gets accomplished at a mine site without the aid of what might mistakenly be considered ‘low tech’ – mechanical systems comprising the shafts, bearings, couplings, gears, clutches and brakes that transmit raw power from an energy source to equipment that needs massive but tightly controlled levels of torque and speed. It’s also sometimes difficult to keep track of the new features that manufacturers continually incorporate into their powertrain products because they often serve as components in subassemblies or individual systems in a larger OEM product. E&MJ spoke with several leading vendors of power transmission equipment to get a better idea of the challenges, trends and opportunities in the mechanical systems sector.

Familiar Failures

Mick Leger, business development manager for Motion, an industrial parts supplier that offers millions of MRO/OEM parts through 500 service locations in North America, commented that “The most prevalent mechanical component failures usually fall into familiar buckets, with vibration, lubrication, heat and misalignment as the major contributing factors. 

“Using current technology in condition monitoring, ranging from simple to highly sophisticated, is an efficient way to increase productivity and avoid unnecessary downtime expense. Systems today can be as easy as green, yellow and red warnings on devices to very comprehensive data reports, which can be cloud-based or even sent to an isolated server for customer data security and easy access. Each comes in variable price points based on the end-user’s goals. 

“Motion partners with manufacturers with the latest technology from each cost entry point. Our account representatives and service technicians can train end-user employees or perform this work as desired,” he explained.

He continued: “One of the steps our mining customers take is to partner with Motion to manage the complete PT component life cycle. This includes selecting product designed with the latest technology and superior efficiency. We also administer any necessary repair/reconditioning and upgrade existing components to higher efficiency and standards. This may include condition-monitoring devices that report machine or component health in real time. 

“Spares storage with controlled environments and documented maintenance keep our customers’ assets ready for use. Without proper storage, the components degrade from environmental issues such as condensation. The damage is usually not discovered until problems occur during installation and use. Then the spares need to be reconditioned, which means additional cost and possibly downtime. But programs like ours drive down the total cost of ownership.”

We asked Samuel Arnold, Motion’s engineering manager, to comment on the areas of mechanical drive component product design in which he had seen the most progress in terms of efficiency, reliability or cost of operation for mining applications.

“Gearing has made significant advancements in recent years,” he said. “Smaller envelopes provide higher torque transmission and much higher thermal properties through more efficient gear tooth engagement, better gear hardening, and lubrication advancements that keep components lubricated efficiently and reduce heat. Many of these units have more internal standardized bearings to reduce customer inventories and increase product availability in the aftermarket repair process. All minimize cost to the customer, and with manufacturing changes, they reduce downtime and increase production.

“Mechanical couplings have also seen considerable upgrades and change over the past years. The efficient transmission of torque, with easy installation and higher tolerance of misalignment, has been a great help for many customers who have struggled with those issues. Some existing couplings can now function properly while tolerating as much as 10 degrees
of misalignment.

“While technically not new or specific to mechanical drive components, condition monitoring or smart-connected devices come to mind,” he noted. “This technology has become more accepted and leveraged in the mining industry in the past few years, providing operators with real-time data on equipment performance. It also gives feedback on issues that may lead to premature failure of drive components. Accessing critical data, especially if this information keeps your operation running by reducing critical failures, has become increasingly important with our industry’s current struggles with long product lead times.”

Mill pinion before and after repair. The old pinion, left, fell victim to harsh operating conditions and was not fit for reuse. As part of the process to rebuild the pinion, Motion collaborated with SKF on a plan to change the bearing housing and install upgraded seals to mitigate contamination and prevent water ingress. The entire assembly, including the coupling, was rebuilt at Motion’s Salt Lake City Repair & Service Center and shipped out ready to install. Motion’s repair teams can recondition many component types, and in most cases, recondition to new. (Photo: Motion)

Measuring Productivity Against Price

The relationship between reliable mechanical drive system performance and site productivity is never more apparent than when a main conveyor suffers catastrophic downtime due to mechanical breakdown. When a failure of this scope results in hundreds of thousands of dollars of production value being lost, the unit cost of a bearing, a shaft or even a gearbox – and the maintenance attention required to keep that component working as designed – shrinks to triviality in the overall economic impact.

Guarding against failures of that magnitude requires mine operators to look at two sides of the same coin: supply and maintenance. Apart from any difficulties a mine operator may encounter in obtaining parts and spares through problematic supply chains, the maintenance resources and knowledge needed to keep critical conveyors running can be an issue, according to Allan Ross, vice-president of CapCorp, the conveyor belt division of Purvis Industries. Purvis has 15 units overall, including CapCorp, KMEC Engineering & Conveying Services, National Mechanical Power Systems and others that enable the Texas, USA-based company to offer a complete industrial product offering. With the inception of its LifeCycle maintenance tracking database program, it provides a service that allows permits its customers to track critical MRO data for components such as conveyor drives, belts, idlers, pulleys and any other mechanical equipment deemed by the customer to be mission-critical.

Ross told E&MJ that, due to the combined effects of an aging workforce and tight labor markets, mining companies may find themselves with smaller maintenance headcounts and fewer “old-hand” workers with many years of experience to draw from. The result, he explained, can be a rise in mechanical-component failures stemming from delayed inspection and repair – or simply from a worker not knowing what to look for to prevent an emerging problem from escalating into a breakdown.

The goal of the LifeCycle program, he said, is to help Purvis and CapCorp demonstrate to customers that the products it sells can help them save money through increased process uptime. “We tell our customers that we sell Tier One products – meaning, the best that we can find in the market. These products are not the lowest cost, but with Lifecycle, we can show them that, in the long run, they wind up with a better value because high-quality Tier One products have longer service lives and cause less downtime.”

The program is set up to survey and catalog the assets identified by the customer as vital to production; components within those assets – mechanical parts, belts and other items that are typically replaced – are then entered into a database designed to track the life of those items from purchase date to installment date and finally, replacement date. That information is enhanced, when possible, with records of purchase receipts, warranty information and photos of the item that show actual or potential problems spotted during inspections. Codes can be entered during inspections, which can be conducted by customer or Purvis personnel, to alert the maintenance organization that regular service, emergency service or replacement may be necessary to prevent a potential failure.

“Obviously,” said Ross, “one of the main objectives of the Lifecycle program is to prevent catastrophic downtime, but through the surveys we can also identify items that aren’t performing correctly or lasting as long as might be expected. For instance, we may spot a broken pulley or worn-out idler that could damage a belt if left unattended. And as an added benefit, we can help the customer keep track of warranty claims.

“We approach this as a partnership arrangement with the customer,” he explained. “There is an upfront charge for the initial asset survey and database setup, but beyond that we only ask that the customer agree to purchase their parts or maintenance services from us when replacement or repairs are needed.”

Purvis Industries/CapCorp’s LifeCycle asset database service enables customers to monitor the status and performance of components vital to production, with the objective of avoiding catastrophic downtime due to mechanical failure. (Photo: Purvis Industries)

New Designs, New Features

To meet the industry’s demands for equipment that delivers superior performance in a data-intensive operational environment, suppliers now can provide power-transmission products that can ‘talk’ fluently to maintenance organizations, in terms of data volume and timeliness, while incorporating designs that often enhance performance and safety while reducing service requirements and downtime intervals. And, with new generations of both stationary and mobile machines offering more power per package size, drivetrain and braking systems suppliers are preparing to meet new challenges.

As one example, the German manufacturer Ringspann recently introduced new models in its FH freewheel series that are equipped with lockout/tagout security (LOTO) features meeting international OSHA guidelines and are capable of providing machine-health information to help maximize uptime performance.

Housing freewheels are typically installed in multi-motor drive systems for generators, pumps, blowers, fans and other equipment as an alternative to the often complex shifting devices frequently used to disengage a powertrain during service. The fully encapsulated FH series units come in six sizes and are rated at nominal torque levels of 1,356 Nm (1,000 ft-lb) to 24,405 Nm (18,000 ft-lb). The new LOTO-enabled freewheel features a hand lever that, when cranked counterclockwise, enables the inner ring of the freewheel with the clamping rollers to disengage with the outer ring in the freewheel housing, thus disconnecting the drive train. The disengagement mechanism allows a system’s drive components to be maintained or replaced without need of interrupting production. The operator can visually control the process through a small viewing window, and the position of the lever can be secured with a padlock.

The FH series can also be equipped with sensor and telematics modules as part of a condition-monitoring system offered by Ringspann that includes data analysis, remote maintenance and integration into higher-level control systems. This allows operators, and maintainers of complex multi-motor systems in particular, to monitor all important power and MRO parameters of the installed freewheels continuously in real-time.

Planetary drives are popular choices for heavy-duty off-road vehicle applications, and there’s a reason for that: they offer high torque transmission with good stiffness and low noise in a footprint that’s more compact than other gearbox types. Powertrain suppliers continue to improve them in response to evolving machinery trends.

“As mobile and industrial applications grow in size to meet more demanding market requirements, planetary drives face increased torque requirements within existing design envelopes,” said Jeroen Decleer, senior vice president, Off-Highway Drive and Motion Systems for Dana Inc. The company’s recent introduction of new planetary drives is part of a series-wide redesign that updates Dana’s technologies with improved torque density, lower package weight, increased input speeds, and more design flexibility.

Dana announced in early 2022 the availability of three new planetary drives with wide ratio ranges, better power density, and modular designs that expand the company’s Spicer Torque-Hub support for tracked and wheeled vehicles. The new drives offer output torque ratings from 80 kNm to 130 kNm and can be configured with Brevini hydraulic motors or Dana TM4 electric motors for a wide range of conventional and next-generation electrified machines, such as drill rigs, track tool carriers and tracked undercarriages. They can also be packaged with hydraulic or electric motors for winches used in a variety of lifting applications, including rotary drilling machinery.

The company’s full line of planetary track drives now offers output torque ratings from 10 kNm to more than 130 kNm, with ratios available from 26:1 up to 210:1. Large drives in the RCT series are engineered to function reliably in extreme conditions from -40° to 120°F (-40° to 50°C). The drives for mobile applications can manage input speeds up to 5,000 rpm and provide heavy-duty bearing load capacities as well as cartridge motor mounts with integrated parking brakes.

The company is also focused on future electrification demands from its mining customers, according to Brad Fowler, Dana’s global platform lead for underground mining, and will offer a flexible portfolio of electrified solutions that allows it to support customers’ specific vehicle needs. 

“As we make the move toward electrification, our portfolio includes system-level and vehicle-level software and controls, which allows us to provide more feedback for optimizing the entire powertrain system,” said Fowler. “As an example, the use of an electric motor enables us to simplify monitoring systems, where things like wheel slip are detectable through the motor instead of additional wheel speed sensors.”

Many mining equipment applications involve the need for gear units capable of handling extremely high output torque. Nord Drivesystems says it has engineered its Maxxdrive and Maxxdrive XT industrial gear units to offer highly configurable, complete solutions that are specifically tailored to heavy-duty application needs with 11 case size options, a wide range of components and add-ons, and the ability to be configured with two, three or four gear stages. 

According to the company, Maxxdrive housings are optimized for strength, rigidity, and high axial and radial load capacities. The Maxxdrive XT design is further enhanced with a larger surface area by way of innovative cooling fin geometry. This allows for increased heat dissipation efficiency, maximizing thermal ratings and effectively eliminating the need for auxiliary cooling systems.

The internal gear components of Maxxdrives are hard-finished and rated to international standards. Maxxdrive units, said Nord, also feature large roller bearings that increase load capacity, reduce friction, and provide a long service life for components. 

The Maxxdrive XT has a symmetrical, mirror-image design that reduces the number of replacement gear units that need to be stocked. Various cooling and heating options provide the drives with flexible temperature management that works to extend lubricant life and efficiency. Maxxdrive units also offer a wide range of options including a fixing element kit, protective cover, torque support, monitoring sensors for temperature, vibration, speed, and oil level, oil heater or cooler, and many others. Additionally, these units can also be outfitted with Nord’s Endurance Package, which adds additional performance and safety features to further protect operators, transported materials, and gear unit components.

Friction Materials Gain Performance

Improved couplings, brakes and friction materials are often needed to accommodate stronger mechanical equipment performance, regardless of whether it’s a tracked, wheeled or stationary machine. 

Flender is now offering a new line of clamping elements for connecting shafts to hubs. The company’s new Fastex new series is aimed at ensuring a superior frictional connection and thus efficient transmission of torque and power through the use of clamping elements that are heavy-duty, compact, and backlash-free. 

According to the company, the Fastex series offer an option other than feather-key designs that can provide advantages for the user depending on the needs of the application. A simple clamping element design allows fast assembly and disassembly: One or more conical pressure rings are pushed onto a conical pressure sleeve using clamping screws. The resulting radial expansion generates radial forces inwards and outwards at the contact surfaces, ensuring frictional locking between the parts involved in the transmission of torque and forces. Flender currently offers ten different types of internal clamping sets and two types of external clamping sets, all of which can be self-centering or non-self-centering.

Carlisle Brake & Friction introduced the SAHR RT series park brake, a spring-applied hydraulically released sliding caliper brake that the company says provides a failsafe design for parking, secondary, and industrial braking needs. Both the caliper and disc require fixed mountings; multiple calipers may be used on a single disc to proportionally increase torque output.

The SAHR RT is suitable for a range of equipment types, including industrial equipment, underground mining vehicles, and more. Carlisle said it features a compact design for mounting that is the same as the current manually actuated RT series brake, and its low-pressure release allows for operation from standard vehicle systems. 

The brake reduces overhang and minimizes bending stress on the supporting members. 

In addition, the brake’s open caliper provides easy access for visual inspection, serviceability, less down time, and lower maintenance costs; it also features simple external linkage adjustment. 

Carlisle also pointed out that these brake assemblies are equipped with the company’s own friction linings. This ensures the brake assembly and the friction linings are designed to work together, allowing Carlisle to provide a wide range of solutions tailoring the final design to each customer’s specific needs. 

Carlisle says its new N680 friction material is designed for extreme thermal stress clutch applications and demonstrates a high coefficient of friction, high thermal capacity, superior noise reduction and resistance to separator plate hot spotting. N680 is suitable for the most demanding noise-sensitive clutch applications and also can be used in brakes with proper density adjustment.

The company also noted that its EPD468 and EPD824 friction materials demonstrate a high capacity for energy absorption and the ability to hold up to abusive conditions in even the harshest off-highway environments. Carlisle’s EPD468 is claimed to last four times longer than the previous industry-leading materials and, according to the company, provides system design teams with the option to increase power output without adjusting system size, along with the ability to reduce system component sizing without sacrificing system power output. EPD824 can be used equally in transmissions and brakes, due to its versatility and superior heat and power resistance. 

“We are seeing an increasing number of power-dense applications, which require materials that can handle higher energy,” said Alessandro Gamba, director of friction research and development at Carlisle. “Our latest solutions answer this need and in turn provide designers an opportunity to reduce the overall footprint of the brake system by reducing the number of discs in the complete system. These innovative friction materials also reduce the transmission package, save on fuel consumption and increase battery life in electric applications.”