After six months of testing at two Waste Management facilities in California, Volvo Construction Equipment says its electric hybrid LX1 prototype loader achieved up to 50 percent fuel efficiency improvement over a comparison machine, well exceeding the 35 percent goal it set for the project.
The LX1, unveiled at the Volvo CE’s Xploration Forum last fall, underwent head-to-head testing with a conventional Volvo L150 loader powered by a 13-liter engine. In comparison, the LX1 uses a significantly smaller 3.6-liter diesel and is designed as a “series hybrid” machine – meaning in part that the engine drives the electric motors mounted at the wheels instead of directly driving the wheels.
During the Xploration Forum, Scott Young, Volvo CE’s electromobility director, explained how the LX1 works: “As opposed to mechanical or hydraulic systems, with electrification we can decouple and move everything around and change the way the machine actually runs. And because subsystems are not linked, they can now be optimized individually, leading to greater efficiency.”
Since the electric motors are on the LX1’s wheel hubs, Volvo was able to change the frame, eliminating the axles and moving the bucket closer to the center of the machine. “This allows us to lift more with a physically smaller machine,” Young says. Additional energy storage led to a reduction in engine size, and now small electric motors propel the machine’s hydraulic system.
With 98 percent new parts – “the only thing we might have used from other machines are the fenders,” Young says – the LX1 is designed to match the performance of a machine that’s one size larger.
It’s hard to imagine a company having a more enthusiastic research project proponent than John Meese, WM’s senior director of heavy equipment. “With the LX1, we’re bringing Star Wars technology to construction equipment,” says the construction equipment industry veteran. “You have the response of the Tesla and the fuel economy of the Prius.”
Meese got a first taste of the LX1 two years ago, operating an earlier iteration at Volvo CE’s research facility in Eskilstuna, Sweden. That Volvo would approach WM with the prototype is understandable: Meese says WM is the largest Volvo CE user in North America, with more than 1,000 construction machines, including 450 loaders.
“I was sold the minute I ran it,” Meese now says. After its Xploration Forum debut, Volvo shipped the LX1 to WM’s Redwood Landfill and Recycling Center in Novato, California.
Whatever Rhonda wants…
Rhonda Lepori took on the real-world operation of the LX1 at Redwood during an unusually rainy winter and spring. She was paired with Mikael Skantz, Volvo CE test engineer. “I saw the LX1 more than I saw my wife,” Skantz now jokes. With Lepori’s input and Skantz’s engineering expertise, the LX1 went through a series of adjustments.
Some loaders have powertrain modes; the LX1 has a “Rhonda” mode. “If Rhonda needed something changed, we could go into the software and make adjustments,” Young says.
For instance, Lepori initially found the LX1 lacking when the loader was pushing and lifting, where the lighter weight of the machine — compared to the L150 — was a factor. “They adjusted lift speeds, back out speeds to how I run it,” she says. “It was slow in the hydraulics and jumped out of a pile, but they made it smooth. For moving things, the hybrid is a lot faster. You just have to work it differently.”
Operators used to the familiar rumble of a diesel might find travel in the LX1 eerily quiet. The whine of the electric motors is most noticeable during bucket lift, load and dump. Lift and tilt work together at the same time using a right-hand lever. “Normally, you do lifting and then tilting,” Skantz explains, “but because we’ve decoupled everything, you can do both together at the same time.” The throttle is used instead of braking, reducing foot movement.
“It’s so quiet you don’t have to wear earplugs,” Lepori says. There is, however, a potential downside to the quiet: “I go around a lot of piles that are blind, and so I had to be careful that people could hear me,” she says.
At the green waste composting Redwood site, which typically receives around 500 tons of material a day, Lepori typically was moving material between stockpiles. The active charging software in the machine detected work patterns and anticipated power needs, charging the machine advance. “The machine knows that when Rhonda is doing a certain type of work, then it’s likely she’ll be doing a task that will need more power,” Skantz says. “It is programmed to be smart enough to charge the battery in advance.”
Users can set the level of battery charging. At WM, the engine kicked in when the battery got to 35 percent of its capacity. Battery life has not been tested on the LX1: Volvo CE’s parent company, Volvo Group, is seeing a five to eight year battery life in its hybrid buses, however. Battery power density advances and cost reductions will help make the loader more commercial, Young says.
The LX1 was also tested at WM’s transfer station in Moreno Valley, California, where the LX1 was working in tight quarters loading trucks, as opposed to Redwood’s open spaces.
“At Redwood, we wanted the machine to be as nimble as possible, and go from zero to maximum safe operating speed quickly,” Meese says. “We wanted to quickly fill the bucket and dump it.” The Moreno Valley facility is primarily a loading operation, requiring fewer tweaks of the operator settings.
The LX1’s ability to reduce wheel slippage by controlling the torque at each wheel was an important factor at the transfer station, however. “We pay $4 million a year on tires in our transfer stations, primarily because of wheel slippage on wet floors,” Meese says. “If that number can be significantly reduced, that’s important beyond fuel efficiency.”
Not that Meese is discounting the LX1’s fuel efficiency potential. On the baseline L150 loader, Meese estimates a fuel burn of 7 to 9 gallons per hour on an 8- or 10-hour shift. “Compare that to the 3.6-liter LX1, which has an engine the same size as in my F-150, running occasionally at 4 gallons per hour. There’s a potential for dramatic savings.”
Another feature that was important in both WM test facilities: the “clean line” underneath the machine, made possible by eliminating axles and differential housing, since motors power each wheel. “There’s very little there for material to wrap up in, because nothing’s really exposed, which is huge from a maintenance standpoint,” Meese explains.
Then there’s the sloping hood. Unlike conventional loaders that need to deal with the space requirements of emissions control components, the green-already LX1’s hood contour allows the operator to see a person in close range to the machine. “It may look like a sexy design, but it has real safety benefits,” Meese says.
Still on the wish list
Since the LX1’s loader pivot pins positioned the bucket closer into the machine body’s center, there’s also been a reduction in the machine’s ability to reach up and over. That’s something WM would like to see adjusted, since it typically buys 2 ½- to 3-feet lift arm extensions to get the lift height it needs, eliminating the need to use a larger machine. This is particularly in important in transfer station operations where the extra reach helps the company evenly load trucks.
“The lift arm extensions give us much more versatility in each class of machine,” Meese says. “In stockpiling, for instance, the extra reach allows us to safely stockpile to the top of the pile without the machine climbing into the pile.”
Technical support is another challenge Meese sees if the LX1 reaches production. “We won’t have the in-house capabilities to do software diagnostics, so there’s really an onus on the dealer to bring up the level of their technician’s knowledge. We really have to depend on our dealer partners to bring their A game.”
Pulling the trigger on a buy decision on a potential LX1 production unit will be a matter of being able to make a business case, Meese says. Factors include how much savings can be realized on tire life, fuel savings and the ability to extend operating hours because of reduced machine noise. Also in the mix for WM will be whether the LX1 gives them recognition as a green-operating company.
The project was funded in part by an $1.8 million California Energy Commission through its Alternative and Renewable Fuel and Vehicle Technology Program. CALSTART, an organization aimed at “growing a high-tech green transportation industry” according to its website, conducted the project’s fuel efficiency and greenhouse gas emission tests. Volvo says the test results equate to a 35 percent reduction in fuel consumption and greenhouse gas emissions.
While the LX1 was working in the California rain, Volvo tested a sister LX1 prototype in Sweden. After being the star of the press event last week, the LX1 used in California is heading back to Sweden for further testing.
CALSTART will issue the official test report September. Right now, Volvo CE is not making predictions about when the LX1 will – if ever – reach the production line. “But before we launch a machine like the LX1, you can expect to see elements of this design incorporated into our products,” Young says. In the meantime, the LX1 is one of the key machines that Volvo is using in its Electric Site quarry research, to be completed in 2018. And in May, Volvo announced its EX2, a fully electric compact excavator prototype, which uses two lithium ion batteries to replace the engine and electromechanical linear actuators to replace the hydraulics system.