Improvements in hydraulic systems are also playing a significant role in maximizing fuel economy.
According to Wall, load-sensing hydraulics have perhaps contributed the most toward improving excavator fuel efficiency. “They have less demand on the engine and therefore reduce fuel consumption,” he says.
Manufacturers are also incorporating more sophisticated hydraulic functions that allow the operator to adjust hydraulic flow to the application. For example, hydraulic upgrades on Hyundai’s latest models include selectable modes to optimize available hydraulic speed and power, plus a manual throttle dial to adjust engine speed and power as needed. “Or put it in the automatic modes and the computer will handle the rest,” says Pooley.
Many excavator designs incorporate an Economy mode. “By putting it in the Economy mode, you still have many of the same abilities as in Power mode,” says Robson of Komatsu excavators, “but fuel efficiency is going to be greatly increased. You can see anywhere up to 10%.”
Wall claims the fuel savings on Deere’s C-series can be even higher. “Tests conducted by Deere show that operating in E (Economy) mode can improve fuel economy by as much as 20%,” he states. The units also feature an Auto-Accel mode that varies engine rpm according to system pressure. “In light load applications, this mode can save the owner approximately 10% in fuel, reducing owning and operating costs.”
For its new Dash-8 models, Komatsu has incorporated an upgraded “multi-monitor” with an Eco gauge, initially available in the 220 size class. The gauge is essentially an energy-saving guidance system. “If it senses the machine is working light, it’s going to report that you’re in an Economy range,” Robson explains. “It’s monitoring the load factor on the engine and reporting it back graphically to the operator.”
Features that enable the operator to properly match engine and hydraulic performance to the job ultimately improve fuel efficiency by prioritizing functions, rather than trying to provide peak performance on every working function of the excavator, Wall points out.
Of course, it’s up to the operator to choose to utilize these features. “The work modes save fuel because the engine doesn’t have to work as hard,” says Jon D’Allessandro at D’Allessandro Corp. However, his operators use them only about 30% to 40% of the time. “If they’re doing some backfilling of trenches, pavement preparation or grading around a building, they’ll put it in a different mode where it’s a little more sensitive. It’s more responsive for them. But if they’re craning, they will run them wide open so they have the power and responsiveness they need.”
Beyond fuel efficiency
D’Allessandro feels it is important to review manufacturer statistics and compare fuel efficiency ratings between brands. However, he cautions that fuel efficiency is not the only criteria to consider. “I like to buy the machines that I know are tested and true, and I’m a big proponent of zero tailswing machines,” he states. “I’m getting my efficiencies and economics through other things, not just fuel.”
McGreavy agrees, adding, “It really comes down to the individual owner and what they’re looking for. Are they looking for pricing? Are they looking for fuel efficiency? Are they looking for operating cost over the lifespan of the machine? Or are they driven by brand loyalty? That’s the question a lot of people have to ask. You have to have an open mind and look at the entire picture.”