The dramatic run-up in the price of diesel fuel has highlighted the impact of fuel efficiency on profits for onsite installers. “Just a few years ago not many equipment owners were talking to us about fuel consumption,” says Peter Robson, excavator product manager for Komatsu. “Today, we can have a very lengthy conversation about it.”
Fortunately, today’s excavators, backhoes and compact loaders do more work with less fuel than the models of 10 or even five years ago. Much of the efficiency increase is driven by federal regulations requiring new off-road diesel engines to meet a series of increasingly stringent standards for reducing exhaust emissions. Tier 1, 2 and 3 emissions standards were phased in from 1996 to 2008. The final Tier 4 standards are to become effective between 2008 and 2015.
As it turns out, the technology required to meet these standards also helps cut fuel consumption. Consider the latest engines from John Deere Power Systems. “These engines are significantly more fuel-efficient than they were five years ago,” reports Doug Laudick, product manager. “Our Tier 3 PowerTech Plus engines achieved record fuel economy gains over our Tier 2 models while maintaining or improving other performance characteristics.”
Among the fuel-saving features of these Tier 3 engines are a variable geometry turbocharger (VGT), which adjusts exhaust pressure based on load and speed to improve performance while providing best-in-class fuel economy. Air-to-air after-cooling, the most efficient method of cooling intake air, enables the engines to meet emissions regulations with better fuel economy and the lowest installed costs.
Better technology
One of the biggest advances for improving fuel efficiency has been the switch from the mechanical fuel pump controlled by a throttle linkage to electronic control of fuel injection. With the Tier 3 engines of Case CX B Series excavators, for example, this technology has improved fuel efficiency by up to 20 percent, notes Rick Hall, product development manager with Case Construction Equipment.
“This system better matches the power produced by the engine with the power required by the transmission and hydraulic and hydrostatic pumps,” he says. “As a result, the engine doesn’t run faster than needed for the job, saving significant amounts of fuel.”
Meanwhile, engineers are working to improve combustion efficiency by increasing combustion pressures. “The idea is to make sure there’s the right amount of air for the specific amount of fuel at just the right time,” Hall says.
Improvements in the design of hydraulic systems have also cut fuel consumption. “One thing we’ve done at Komatsu is to reduce restrictions to oil flow and reduce back pressures that caused a parasitic draw of power on hydraulic systems,” says Robson.
Another fuel-saving advance has been to replace the mechanical-hydraulic link between engine and variable-displacement hydraulic pumps for controlling hydraulic flow with a fly-by-wire system that features electronic signals and variable-displacement piston pumps. “This fly-by-wire system produces a much faster response of the hydraulic pump for much more efficient fuel use,” Robson says.
Better data management
Accurate information also plays a critical role in making most efficient use of your machine and the fuel to operate it. “The key to machine efficiency is not how much horsepower you have, but how well you manage it,” Robson says. “If you can’t manage it efficiently, you’ll spend a lot of extra money on fuel.”
That’s where Komatsu’s KOMTRAX wireless equipment monitoring system can pay off. It uses a network of satellites to relay basic and critical performance data from your machine to your computer. The system is available on most of the company’s Tier 3 engine equipment and can be retrofitted on older machines and non-Komatsu equipment.
KOMTRAX provides information on various machine functions and operations, including actual fuel consumption, average hourly fuel consumption, residual fuel level, actual working hours (engine on time less idle time), hours spent in four different load levels (very heavy, heavy, light and very light) and various modes of operation, such as digging, traveling, hydraulic relief, power mode, economy mode and lifting mode. Such data can reveal opportunities for using equipment and fuel more efficiently.
“For example, this system might show that your machine is being used 80 percent of the time in light-duty applications in the full power mode,” Robson says. “Knowing that, you might be able to do the same amount of work using economy mode and reduce fuel costs. Or, the system might show that 40 percent of the time when the machine is operating, the engine is running at idle. Shutting off the engine at those times would also save you money.”
Diesel-electric machines
At ConExpo in Las Vegas last March, a number of manufacturers displayed prototypes of hybrid engines designed to save fuel by combining a diesel engine with an electric motor. In June, Komatsu began selling the world’s first hybrid excavator to the Japanese market.
The PC200-8 Hybrid uses a newly developed electric motor, which replaces a conventional hydraulic motor, to turn the upper structure. The system also uses a capacitor to store the energy generated as the upper structure slows when turning. It then discharges the electrical energy to a power generation motor that assists the diesel engine when it accelerates. Compared to the standard PC200-8, this hybrid version has reduced fuel consumption an average of 25 percent, the company reports.
“We look forward to when such technology will come to North America, but everyone can benefit from using what we currently have more efficiently,” Robson says.
Case is taking a go-slow approach to hybrid engines, Hall notes. “Everyone in the industry is watching development of hybrid technology very closely,” he says. “Because of a significantly higher purchase price and possibly higher maintenance costs, the payback period is much longer than most equipment owners are comfortable with today. However, that’s not to say that hybrid machines won’t be more common in the future.”
Greg Northcutt is a freelance writer based in Port Orchard, Wash. He can be reached by e-mailing this publication at editor@onsiteinstaller.com.
