A major highlight from the Manitowoc stand at the bauma 2022 trade show was the launch of the Grove hybrid initiative on its all-terrain crane.
John Benton, Director of Engineering, is responsible for a team of specialists working in the Future Projects department of mobile cranes developer Grove. He spoke exclusively to Cranes and Lifting about the initiative and Grove’s aims and expectations around hybrid technologies.
Benton has been with Manitowoc for 16 years. He joined as a structural analyst and for the last decade he has been working as a crane architect, providing systems engineering for new products. Most of the projects have been both Grove rough terrain and truck mounted cranes. But over the years he’s been involved in joint projects leading the development of Grove’s “GMK” line-up of all-terrain cranes. Benton made the move to head up the Future Projects department in Germany, 12 months ago.
Benton discusses the background of the hybrid initiative and the aims and objectives of the project.
“A few years ago, the team working in our Future Projects department was working on a number of concepts examining what the future mobile crane could look like. They went through an analysis of examining what was technically possible in terms of power requirements, weight requirements, and overall system architectures,”he says.
“We presented a paper on these concepts several years ago, basically telling the industry, ‘we see that this is coming in the future, and we think it could look like this.’ The COVID pandemic disrupted the development in terms of what we could accomplish. Out of the multiple concepts that were possible, we decided to go for what we thought was the most advanced solution in order to learn as much as possible as quickly as possible, in order to be a leader in terms of the efficiency of the final product in the ecosystem of these hybrid concepts.”
As a result, Grove decided to put in a single motor and a generator that can generate the electricity required, thus providing the possibility of operating the crane without running the diesel engine.
“We felt the technology was there to go farther than that. What you saw at bauma was our engineers showcasing their first concept in order to prove what’s possible to go farther in the electrification of a mobile crane than simply providing a single motor,” said Benton.
“What that opens up for us is the possibility to use technology that we’ve had on tower cranes for many, many years, with direct electric power to the hoist and to the slew drives.
“Both of those rotary motions are something that we think is naturally headed toward direct electrification and the biggest question was about the integration of that and what else it might affect, and how we could optimise the design to stay within the weight limits of a mobile product.”
Benton confirms which Grove model the Future Projects team worked with, and what they have managed to electrify and discusses the performance of the hybrid.
“Given the timing of the project, we had just released the Grove GMK 4100L-2 to the market and so we decided that we would start with that latest generation all terrain crane, already the highest performance four axle product that we have, and build on top of that.
“The architecture for that model is a single engine design, and so we wanted to work from that as a starting point because it is already a very well-optimised design.
“We searched to see what kind of mobile hoist technologies were available. For this machine, we decided that the 19mm hoist, which was already on the crane, had excellent weight performance ratio and so we simply integrated a high performance motor to the hoist.
“That product has a long history of us knowing about its reliability and its performance. So, there’s been optimisation done about how the control works in order to make this hoist responsive, and we retained the braking system that was already on the hydraulic version of the hoist,” he said.
“In the case of the slew drives, we found that it was possible to integrate motors into those drives as well, and we were able to achieve in both cases the same or better performance to what we had in the hydraulic version. The line pull of the hoist is the same as it was before, and the speed is the same, too.
“With slew drives, we actually have a little wider range of speed available to us. But one of the really exciting things about the slew drives is that it also gives us really fine control over small movements of that system. We’re exploring this to really understand what that can bring to the user in terms of actual use with moving loads at a long radius and precise movements of the load in those situations.
The hybrid includes a Euromot 5 diesel engine and features a battery system which manages the hoist and slew plus powering the hydraulics for the luff and telescoping operations. The battery is also charged by the diesel engine and regenerates energy from the rotary functions.
“For those that are familiar with our single engine concept today in the GMK 4100L-2, we’ve removed the mechanical drive that was in the centre of the bearing and was providing mechanical power to the hydraulic system in the superstructure. As an alternative, we’ve installed a generator in its place in the carrier, and we have two different power sources for the superstructure. One source is the diesel engine which can drive the generator and can directly drive electricity into the superstructure. The other possibility is that the generator can charge the battery and then the battery can drive the superstructure.
“We also integrated a charging system so you can plug the crane into a 32 amp service and you can charge at that point in a totally ‘emissions free way’,” he said.
Benton elaborates on where the Future Projects group is headed with the concept and what the market can expect to see from Grove over the next five years of development.
“I think you will see a real focus on improving the efficiency of our systems. I think we’ll see that industry-wide, but at Manitowoc, we have multiple projects that we’re working on in this space.
“We can’t yet discuss some of those, but we pride ourselves in listening to our customers and responding very quickly to their needs. So bauma was a really exciting time for us going into the show.
“There was some uncertainty about whether we would find the first customers for this solution, but the response has been overwhelmingly positive. And now we’re further discussing with those customers to tailor our solution to exactly what they need. We are really excited to learn that customers see this the way that we do, which is that they want the flexibility of powering the crane from electric sources, but they also want to achieve better efficiency and better performance while they’re operating.
“It seems Australia, with all the mineral resources and the focus on the environment is a perfect location for our Grove solutions,” he said.
Benton goes on to discuss how quickly Grove will be able to commercialise and manufacture the hybrid.
“We don’t have an exact timeline for that. That said, we’re in the test phase now with our concept and we’re architecting the solutions based on customers’ feedback. What I can say is that it’s a very fast-moving environment in this entire space of electrification, and so you should expect to see things advancing rapidly from Manitowoc in this area,” he said.