Komatsu America’s product manager for hydraulic excavators, Armando Nájera, has learned what to typically expect when initially discussing the company’s new HB215LC-1 hybrid with an excavator user. He knows that, more often than not, the contractor will be skeptical of the hybrid’s capabilities, compared with the proven performance of its conventional counterpart, the PC200LC-8. But Nájera has enough experience with the HB215LC-1 to give potential buyers an unhesitating response:

“I can look people in the eye and tell them that they’re not giving up anything by having a hybrid—other than not spending as much on fuel. There are no performance drawbacks.”

To put Nájera’s “no performance drawbacks” statement to the test, Construction Equipment editors recently worked with Komatsu America to compare the HB215LC-1 hybrid with the PC200LC-8, running the machines bucket-to-bucket in a series of tests, including trenching and truck-loading, as well as a “multiple-application” evaluation developed by Komatsu’s testing unit. Each test allowed us to compare the two machines’ potential production capacity and their fuel efficiency (work done per gallon of fuel).

The HB215LC-1 and the PC200LC-8 are structurally similar, using the same undercarriage, cab, boom, digging arms and buckets. For our evaluation, both were fitted with an 18-foot 8-inch boom, 9-foot 7-inch digging arm, and 42-inch-wide bucket having a heaped rating (SAE) of 1.34 cubic yards. We conducted the evaluation during the third week of May at Komatsu’s training facility in Cartersville, Ga., where the machines worked in a mostly clay material weighing an estimated 2,850 pounds per cubic yard.

Our operator for the evaluation was Russ Peters, a principal in Red’s Excavating, a firm based in Green Bay, Wis., and specializing in all types of grading and excavating, as well as installation of sewer and water laterals. Peters’ firm owns five Komatsu excavators, including two PC200LCs and an HB215LC-1. The company was among the first excavator-using contractors that Komatsu asked to evaluate the initial hybrids brought to North America in fall 2009. Based on the hybrid’s performance, Peters subsequently made a rental-purchase agreement on an HB215LC-1, which currently remains in his fleet.

Peters admits he’s the kind of operator who continually refines his technique to get the best from any machine—and that he has taken a special interest in the hybrid.

“I have almost two seasons tweaking operation on the hybrid,” says Peters, “and I’ve found that making a few simple changes in technique, compared to the PC200, makes a positive difference in performance.” 

EDITOR’S NOTE: Komatsu emphasizes that the HB215LC-1 is designed to be the PC200LC-8’s equal in regard to production capacity, and, subsequently, the company’s marketing approach makes only the claim that the hybrid will use less fuel than its conventional counterpart. Respecting Komatsu’s marketing strategy, Construction Equipment has chosen not to publish exact numbers resulting from production studies between the two machines during testing. We do report, however,  which machine was more productive in each test event and why we found it to be so.

Hybrid history

According to Nájera, Komatsu’s first hybrid excavator, the PC200LC-8 Hybrid, was introduced mid-2008 in Japan. The machine gained rapid popularity in Far Eastern markets, he says, and the current hybrid population worldwide numbers some 700 units. When Komatsu brought 10 hybrids to North America in late 2009, the company placed them in varied applications across the United States and Canada, including EPA nonattainment areas.

“At that time,” says Nájera, “the overall market for machines was down and fuel prices were relatively low—probably not the best time to introduce a hybrid with a price premium.”

An initial sales obstacle in North America, says Nájera, was that potential buyers compared the machine to hybrid cars, voicing concerns that the machine would not only cost more initially, but also would require expensive maintenance, such as replacing a pricey battery pack.

“We had a challenge explaining that the hybrid uses no battery pack, and that the machine is designed as a package to incorporate electrical components that could well outlast conventional components,” he says. “We can now substantiate that claim, because some of the early machines are approaching 14,000 hours of service. Now, with the HB215LC-1, we have an even more refined version of the hybrid concept.”

Hybrid design

The design of the HB215LC-1 is relatively straightforward, using four major electrical components not found in its conventional counterpart: a generator motor, inverter, capacitor and electric swing motor.

The generator motor is placed between the engine and the hydraulic-pump drive and is integrated with the engine flywheel. When serving as a generator, the generator motor sends AC current to the inverter, which converts the AC power to DC and directs it to the capacitor. The capacitor’s job is quick storage of the DC power and rapid release of the power to the swing motor or to the generator motor.

At the heart of Komatsu’s hybrid design is the swing motor’s ability to generate electricity from the energy produced when the motor brakes the upper structure at the end of a swing cycle.

Because braking forces are so great, says Komatsu, the system generates a large amount of electricity, which is sent to the capacitor for storage. The stored energy can be used in two ways: to power the swing motor or to power the generator motor. If power is sent to the latter, then this component now serves as an electric motor to assist the engine in driving the hydraulic pumps.

Read the rest of the article at constructionequipment.com