Earth-movers & shakers
August 1, 2013 by Patrick Callan
It has been five years since Komatsu Ltd. introduced the world’s first hybrid construction equipment: the PC200-8 hybrid hydraulic excavator. It was a project that had been on the company’s radar since it began developing hybrid technology in the late 1990s. With a newly developed electric motor, it was designed to cut fuel costs by 25 per cent and significantly reduce its carbon footprint compared with conventional machines.
Komatsu is now on its second generation excavator, the HB215LC-1, and the move to hybrid technology has been gaining
momentum amongst other construction giants. Caterpillar and John Deere have recently released their own hybrid construction machines in response to demands from customers for increased fuel efficiency, ease of operation, reliability and productivity. They want all of this while meeting tougher emission requirements.
With that in mind, On-Site felt the time was ripe to take a closer look at these hybrid machines: Komatsu’s HB215LC-1 hydraulic excavator, John Deere’s 644K hybrid wheel loader and Caterpillar’s 336E H hydraulic excavator. To see how they stack up against conventional machines we quizzed product experts.
How does hybrid technology work?
Rob Orlowski, Komatsu’s excavator product manager, says simply put: a true hybrid uses short-term storage of energy that would otherwise be wasted, and it releases that stored energy to power the equipment.
He explains in Komatsu’s HB215LC-1 the electric energy is captured during each swing break and stored in the ultra-capacitor; whose ability to quickly charge and discharge energy makes it ideal for this equipment application.
The ultra-capacitor helps power the swing motor and sends energy to the engine via the generator motor. The energy, he says, is then used to accelerate the engine to improve the hydraulic response of the hybrid, and the additional power is available to the engine and hydraulics. But Orlowski warns, “A customer should always be mindful when a manufacturer calls their equipment a hybrid to insure they are truly getting the fuel savings benefits of a true hybrid.”
John Chesterman, wheel loader product marketing manager for John Deere, says the diesel engine in the 644K runs at constant speed and powers an electric generator. The energy from that generator then goes into “power electronics,” which controls the amount of electric energy that’s going to a single, brushless, AC electric motor. The motor drives into a “simplified transmission.”
“It does not even have a reverse gear,” he says. “Electric motors, they work perfectly well in forward and reverse. All the
reversals of this machine are done with the electric motor, so we’re eliminating shifting that every wheel loader does.”
He says the transmission only needs three gears, although it does have four operating speed ranges. “What’s coming out of that transmission are the drive shafts that go to the front rear axle. That part of it is basically identical to our conventional drive machine,” he explains.
The key with this hybrid drive, he says, is the constant speed increases engine efficiency. The engine does not have to “lug” its way up and down the whole rpm band as it would in a conventional drive wheel loader.
An added bonus of the constant speed is “it’s very quick to respond.” At 1,800 rpms the hybrid is operating very close to its maximum power, meaning the machine can have a lot of pushing power very quickly and full flow is available at almost any time.
“With the hybrid, we’re always at a constant speed so the hydraulics are very quick and snappy,” he says.
When it comes to Caterpillar’s 336E H, the design uses three key building block technologies, according to advanced technology development manager Randy Peterson.
The electronic standardized programmable pump transitions between the hydraulic hybrid power sources, engine and
The Adaptive Control System valve manages restrictions and flows to control machine motion with no loss of power and ensures operators experience no difference in control, hydraulic power or lift capability.
The hydraulic hybrid swing system captures the excavator’s upper structure swing brake energy in accumulators, and then
releases the energy during swing acceleration.
Why switch from conventional models?
Although hybrids cost between 10 to 20 per cent more than conventional models, Orlowski says their 25 per cent reduction in fuel consumption and carbon dioxide emissions are prime selling features. And he points out another reason why hybrids are trending. “One of the first things you will notice about the HB215LC-1 is that it is quiet,” he says.
To put these fuel savings in perspective, a 25 per cent reduction is equivalent to removing 12 passenger cars off the road each year, adds Peterson.
Chesterman explains another key advantage of a hybrid over a conventional model is its ease of operation. “One of the things we consistently hear about is making machines easier to operate,” he says. “To load the bucket on this machine and make it perform like an expert operator—the learning curve is very, very easy.”
How are they operated?
Since Komatsu’s hybrid technology simply captures energy that would normally have gone to waste there is nothing different that the operator needs to do during the course of operation, says Orlowski.
“The hybrid’s actually easier to operate,” quips Chesterman. “If the operator knows how to operate the conventional machine, if they hop in this machine, all the controls will be identical except for three minor buttons.” There is no compromise in terms of productivity and no trade off in hauling or trunk capacity, he adds.
Based on customer feedback, one of the design requirements was to make the hybrid system completely transparent to the
operator, says Peterson.
How are they being marketed?
Komatsu’s excavators are primarily being marketed at contractors who are conscious of the environment and looking to cut their fuel costs. “Komatsu believes that ecology is intertwined with the economy and our industry,” says Orlowski.
John Deere’s dealers have been focusing on customers that are “sensitive to fuel consumption changes,” according to Chesterman. “A long-term customer need we hear about consistently is reduced fuel consumption,” he says. “Some customers are willing to invest to minimize their sensitivity to fuel [price] changes,” he says, while others are interested in hybrids for sustainability reasons.
For Caterpillar, the marketing focus is on the return for the customer by lowering their owning and operating costs. Peterson notes the 336E H is more productive and up to 50 per cent more efficient (ton/liter) than the previous model 336D. “Customer payback is as little as one year depending on hour accumulation, fuel cost and job site,” he says.
Orlowski says contractors have remarked about the quietness and responsiveness of the hybrid excavator. They’ve been able to achieve the same production as a conventional machine—plus there is the added benefit of a significant fuel savings. “Contractors have the opportunity to be the first environmental stewards while maintaining profitability and competitiveness,” he says.
So far customers are very interested in the technology, especially those in the more “sustainability sensitive areas,” according to Chesterman. “We have some customers who are very interested in it due to the fuel consumption reduction and the greenhouse gas reduction.” h
e says. The main thing, he emphasizes, is that people understand the performance along with the fuel consumption savings.
Peterson states customer feedback has been nothing short of phenomenal. “Customers have been surprised that a machine as quiet as the 336E H Hybrid can still be so powerful,” he says. Production studies with customer operators have demonstrated performance and fuel savings even above what we have advertised. “Not only have they been impressed with the simplicity and ease of serviceability, but also with how reliable the machine is,” he adds.
Have there been any challenges?
Many operators are skeptical or surprised by how quiet hybrid construction machines are, says Orlowski. However, he counters, “This is a good feature.” He continues, “Once they realize it has the same power as a standard non-hybrid excavator they become used to the noise levels and start to appreciate it more.”
A major hurdle, says Chesterman, has been convincing customers that hybrids also offer better performance and ease of operation. Like Orlowski, he says as soon as operators get their hands on these machines they quickly realize what they can do. “Once they try the 644K hybrid, they are very impressed when compared to the conventional loaders with torque converter, powershift or hydrostatic transmissions that they are running today,” he says.
Peterson says the multifaceted nature of a hybrid excavator has created what engineers have dubbed “the three-headed
monster” during the design phase: maintaining productivity and controllability while improving efficiency. “Sometimes they can be conflicting requirements,” he says. “When you add another source of power—the accumulator in this case—it creates an additional level of integration.”
So, what’s next for hybrids?
When asked if they have plans to bolster or expand their hybrid fleets, each respective company kept its cards close to its chest, unwilling to give away too much information. But they did reveal that we can expect to see more in the years ahead—and not only when it comes to big iron.
With hybrid technology now firmly in place in the construction industry, existing models will continue to be refined while the viability of the technology across others product lines will be tested.
The success of hybrid construction equipment will weigh heavily on manufacturers’ ability to convince customers that not only do they balance demands for better fuel economy with increased productivity, they also mitigate the carbon footprint left
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John Deere’s 644K hybrid loader
• Started showing hybrid machines as a concept at Con Expo in 2011, put wheel loader on the market this spring
• Operating weight: 18,341– 19,099 kg.
• Interim Tier 4-emission certified engine; runs at constant rpm; 229 hp. at 1,700 rpms
• Bucket capacity 4.25 yd³
• Consumes on average 25 per cent less fuel than John Deere’s conventional 644 loader.
Caterpillar’s 336E H hydraulic hybrid excavator
• Unveiled in October 2012, launched at Bauma 2013
• Operating weight: 37,200 kg. Cat C9.3 ACERT Tier 4 Interim engine
• Bucket capacity of 3.33 yd³
• Up to 25 per cent less fuel compared to a standard 336E and up to a 50 per cent improvement in fuel efficiency compared to a 336D
Komatsu’s hybrid HB215LC-1 hydraulic excavator
• Launched in North America in March 2011
• Operating weight: 21,228 kg.
• 148 hp. diesel engine, 2000rpm
• Bucket capacity of 1.57 yd³
• Saves an average of 25 per cent fuel with an equivalent reduction in carbon dioxide emissions compared to the
standard excavator model.
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