One unmistakable take-away from this year’s bauma show was the buzz surrounding electrification. The idea of massive mobile machines running only on batteries may seem far-fetched, but for smaller equipment it has become a reality. At every turn, major manufacturers like Cat, Kobelco, Komatsu and Volvo to niche players like Ecovolve and Giant featured electrified excavators and loaders.
Komatsu’s small electric excavator runs much quieter and matches the speed and productivity of an equivalent diesel-powered PC30. Pre-production units are currently working at customer sites in Japan.
Why the increasing focus on electric construction machines? “There are different reasons. Some people are interested just from an ecology green perspective,” said Caterpillar’s Elie Abi-Karam. “For others, regulatory issues — in Europe especially — are driving people to lower their emissions. Electrification is the next step, creating a machine that effectively has zero emissions.”
Bobcat is specifically addressing indoor applications such as demolition and basement construction with its new E10e battery-powered, 1-ton mini-excavator. The industry is definitely moving in this direction, said Product Line Director Jarry Fiser. “In developing the E10e, we are not just demonstrating technology for the sake of it. We are providing a product that offers clear customer benefits.” As well as indoor projects, many other sites will require low-noise, zero emission machines, he said, including urban/city-center developments, night-time work and quiet zones such as hospitals, cemeteries and schools.
All of the machines at bauma were first-generation — basically engine out, batteries in. At this initial phase of electrification it’s still about powering existing hydraulics. “In the first step, OEMs don’t want to completely change the architecture of the machines,” said Bosch Rexroth’s Bernd Schunk. “They just want a plug-and-play solution. And, to be honest, they are all a little bit reluctant to change everything at the same time.” Next-generation machines, however, may bring modifications such as electric drives replacing hydraulic rotary drives on excavators, he said.
Schunk said his company’s engineers are working to further optimize the design, performance and efficiency of products like axial-piston pumps specifically for electrification. “It makes a huge difference whether you use a diesel engine or electric drive, and it’s even more challenging if you have batteries inside.” That’s because the load cycle and battery life play a major role in whether a machine is successful in the market or not, he explained.
One such development specifically targeting this market is the new AX piston pump from Bucher Hydraulics. The 24-piston, load-balanced unit claims extremely high efficiency over a wide speed range, making it ideally suited for use with variable-speed electric drives. Low power losses conserve valuable battery capacity.
Fluid power engineers need to step up their game because there are rumblings about fully electric machines with no hydraulics whatsoever. Wacker Neuson’s Klaus Allerstorfer, for one, can foresee electromechanical actuators as the future. “I definitely think so; the hydraulic system on an excavator is not a given. In the end, it depends on where the industry is going and what suppliers are developing,” he said.
“We only use components in our electric machines that are proven for hard applications and can sustain dust and vibration conditions.” For production machines, that currently means hydraulics, but they’re exploring new technologies in different areas of the excavator, he explained. “It’s always a mix of performance, sustainability and the expectation of long lifetime for the customer. In the end, we want to deliver the best quality, the best performance for zero-emission products as we do for our regular machines.”
