The transition of mobile machinery and off-highway equipment away from fossil fuels may be a long-term goal, but electrification is already delivering real benefits in the sector.
By Tarek Bugaighis • Ewellix
Is the era of the internal combustion engine coming to end? Under pressure to reduce harmful emissions, the automotive industry is already gearing up for a large-scale transition to electric power. Now attention is turning to other mobile machinery applications — especially the types of heavy-duty equipment widely used in agriculture, forestry, construction and municipal roles.
In one survey of the mobile machinery sector, more than 70% of respondents said they thought electric power would eventually become more prominent than fossil-fuel power. More than 86% said that electrification is already becoming a more important topic for their organizations.
But despite the growing interest in the topic, real progress in the electrification of mobile machinery has been slow. More than 40% of respondents to the same industry survey said that electrification hadn’t yet impacted their companies.
Barriers to wholesale electrification include the high cost and limited availability of batteries with sufficient capacity to support demanding real-world operating cycles. In some sectors, access to suitable charging infrastructure can be another important issue.
Baby steps to incorporate electric actuation
However, machine builders and end users are increasingly recognizing that even partial electrification of equipment offers significant cost, reliability, and operational benefits. In off-highway designs, that’s driving renewed interest in hybrid architectures involving a combustion engine to generate electric power for the machine — sometimes in combination with onboard battery storage. Here, the power takeoff from the engine or the hydraulic output can be replaced by an electrical output. That in turn allows use of electromechanical actuators as a real alternative to the hydraulic systems that have dominated the mobile machinery sector for decades — especially in applications necessitating high loads.
Let’s look at those potential benefits in detail. First, there’s efficiency and stability. Electromechanical systems only consume the requested energy per cylinder or actuator when they’re actually moving an axis, and they can be up to 80% efficient in turning input power into useful work. That’s in stark contrast to the 44% end-to-end efficiency of a typical hydraulic power system. Greater energy efficiency means lower CO2 emissions … and represents significant cost savings for operators.
For internal combustion engine vehicles, the fuel costs of fully electromechanical mobile machines can be half those of their diesel-powered counterparts.
For battery electric vehicles, the batteries on board can be halved in size and accept quicker charging. In addition, the recovery of electricity increases the efficiency even further … enabling a reduction in battery costs.
Off-highway equipment use of electric systems can offer other environmental advantages too. Machines with onboard energy storage can be designed to operate under electric power alone for parts of their operating cycle. That makes them much quieter … a real benefit for equipment operating overnight in urban areas, for example. Plus because electromechanical systems don’t use high-pressure oil, the risk of accidents or pollution from fluid leaks is eliminated. That’s a boon for vehicles working in the cities or in clean indoor spaces, but also for agricultural machines and for any equipment that operates in sensitive natural environments.
Several performance premiums with electric actuation
Another consideration is the cost of keeping equipment running. Modern electromechanical actuators offer very high levels of reliability and long operating lifecycles with very little requirement for routine maintenance. Even if an actuator does fail in service, replacement is usually a simple case of swapping the component and connecting a few cables. In contrast, hydraulic systems unfortunately require specialist maintenance expertise and can incur extensive downtime.
Off-highway equipment use of electric systems also boosts productivity. The speed, position, and acceleration of electromechanical actuators can be precisely controlled over their full range of motion, without the need for elaborate additional control equipment. That capability boosts machine performance and is key to new generations of smart machines that must satisfy wider ranges of tasks and operating conditions than in the past — or must dynamically adapt output as commanded by machine controls. The communications cabling between these electronic controls and electromechanical actuators employed on off-highway equipment are usually via simple I/O or some bus communications such as CAN bus.
This connectivity imparts industrial internet of things (IIoT) capabilities in electromechanical actuators — so OEM machine builders and operators get:
• Straightforward access to high-quality data relevant to fleet monitoring and predictive and condition-based maintenance approaches
• Access to real-time data for onboard diagnostics — a key requirement of autonomous vehicles or robots needing self-reliant systems
This IIoT connectivity is possible without the addition of complicated sensor systems needed to collect performance data from hydraulic or pneumatic systems.
Migrating mobile machinery to electromechanical linear actuators
Many of today’s electric-actuator offerings for mobile equipment trace their roots to designs that have been used for decades on road pavers, road sweepers, combine harvesters, lawn mowers, and other work vehicles needing auxiliary adjustment or lifting systems. What’s new is that designing and specifying electromechanical systems in mobile machinery has in recent years become increasingly straightforward.
Most all of these actuators have at their core a dc motor for easy integration into battery-powered and onboard power-generation systems.
Most all of these actuators also have ruggedized and sealed bodies to withstand wild operating temperatures and corrosive outdoor settings.
Beyond that, electric-actuator features are fairly flexible … with some suppliers of electromechanical systems offering highly modular designs to let OEMs tailor performance features to their build in a cost-effective and well-integrated package. Some such actuator manufacturers even provide OEMs additional assistance in this design process … by leveraging years of development, testing, and customer-support experience to help engineer actuator systems specifically designed to satisfy the rigors of mobile applications.
On a related note is a relatively new development in industry — namely, the availability of modular actuators for which heavy-machinery builders can even specify base component features and internal components. These actuators essentially serve as custom-like stock solutions with optimized performance-to-cost ratios.
Ewellix, headquartered in Gothenburg, Sweden, is a global innovator and manufacturer of Linear Motion and Actuation solutions used in industrial automation, medical applications, mobile machinery and distribution. Formerly part of SKF Group, the Ewellix Group employs about 1,400 people and consists of 16 sales units and nine factories. External net sales are approximately 2.3 SEK billion.
Ewellix | www.ewellix.com