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Hybrid Excavator Focused on Fuel Savings


Caterpillar’s 336E H is designed to be sustainable, offer greater fuel efficiency and to lower owning and operating costs.

By Mark S. Kuhar

Caterpillar Inc. unveiled the first model in its new line of hybrid excavators, the Cat 336E H, at its Mossville Industrial Design Center on Oct. 16 at a special trade press event, “The Next Generation is Here.” The new 336E H will be sold and serviced exclusively through the global Cat dealer network following the machine’s official launch at bauma 2013 in Munich, Germany. The order board for the Cat 336E H opens in February 2013, with factory shipments beginning in March 2013.

The Cat 336E H uses a new hydraulic hybrid technology developed by Caterpillar. “A hybrid is independent of any particular technology – it doesn’t have to be electric,” said Ken Gray, global product manager for large hydraulic excavators for Caterpillar’s Excavation Division. “There are many ways to store and reuse energy, including our patented hydraulic hybrid system featured on the Cat 336E H.”

“Caterpillar has developed, built, and tested electric hybrid excavators, but – until now – we had not found a hybrid approach that would actually lower our customers’ owning and operating costs,” Gray said. “Large excavators operate in high-production applications in which fuel is a very significant operating cost for our customers. So the 336E H, the hybrid version of our workhorse 336E, is ideal for introducing our new hydraulic hybrid technology, with its more than 300 filed patents.

“No other commercially available technology has higher power density than hydraulics, and that’s why we selected a hydraulic solution to help our customers achieve substantial fuel savings,” said Gray. “The 336E H also meets stringent Tier 4 Interim/Stage IIIB emission standards. It is extraordinarily quiet, too. So it’s a socially responsible machine for our customers to own, and they will sacrifice nothing in terms of performance, power, force, speed or production. Once more, the owning and operating costs for the 336E H are actually lower than the standard machine. That’s the value customers expect from Cat excavators.”

“Customers aren’t going to choose the 336E H simply because it is sustainable. They will select it because it actually lowers their owning and operating costs, and maintains the performance of the 336E,” said Gary Stampanato, vice president of Caterpillar’s Excavation Division.

Technology
“Caterpillar’s corporate technology strategy centers on research and development in advancing technology to meet customers’ needs today, which is what the 336E H does,” said Tana Utley, Caterpillar’s chief technology officer and vice president of the Product Development and Global Technology Division. “We’re also continuously working on innovations that we anticipate will meet their future needs. That’s why we’re continuing our research and development in electric hybrid technology too, which actually began our hybrid development path several years ago.”

“Caterpillar has an extraordinary team of people working on hybrid technology solutions for the next generation of Cat hydraulic excavators,” added Gray. “They are from every corner of the world, are among the very best and brightest minds, and they are listening very closely to our customers. It’s exciting for me to see their enthusiasm for this project and the quality product they have developed in the 336E H, and we’re just getting started.”

“I am absolutely confident our engineers will continue to discover and develop the best hybrid approaches for Caterpillar’s extensive line of equipment and applications, whether that’s some form of hydraulic or electric hybrid system or something as of yet unknown,” Utley added. “At Caterpillar, we don’t simply engage in creating new technologies like the hydraulic hybrid system just for technology’s sake, or simply to prove that we can. Our technology strategy’s focus never loses sight of what our research and development efforts can mean to our customers’ success – today and in the future.”

Since the introduction of the 300 Series in 1994, the excavators have become standard in a large variety of general, quarry and heavy construction applications. Caterpillar introduced the standard 336E in 2010 as a direct replacement for the 336D. The 336E was introduced primarily to meet Tier 4 Interim/Stage IIIB emissions standards, and like any new Cat machine, the 336E includes several enhancements over its predecessor, including more horsepower with greater fuel efficiency, more lift capability, higher digging force and automatic after-treatment regeneration.

The 336E H has all of the same advantages of the 336E with the biggest difference between the two models being even greater fuel efficiency, according to the company. To achieve added fuel savings, the design of the 336E H uses three building block technologies that:

  • Conserve fuel with engine power management via the Cat Electronic Standardized Programmable (ESP) pump, which smoothly transitions between the hydraulic hybrid power sources, engine and accumulator.
  • Optimize performance using restriction management via the patented Cat Adaptive Control System (ACS) valve, which intelligently manages restrictions and flows to seamlessly control machine motion with no loss of power, and to ensure operators experience no difference in control, hydraulic power or lift capability.
  • Reuse energy via the hydraulic hybrid swing system, which captures the excavator’s upper structure swing brake energy in accumulators, and then releases the energy during swing acceleration.

Fuel Savings
The 336E H delivers up to 50 percent greater fuel efficiency, which is measured in tons per liter, over the 336D. Customers can expect the 336E H to use up to 25 percent less fuel compared to a standard 336E, and up to 33 percent less fuel than the 330/336D, the company said.

All three of the technology building blocks, Conserve, Optimize and Reuse, are integrated together to maximize fuel savings in a variety of applications. Even in low-intensity swing applications, customers will still experience significant fuel savings because of the Conserve and Optimize technologies. (Additional factors, such as operator skill and jobsite conditions, also affect fuel savings.)

Because the 336E H burns less fuel and reduces regulated engine emissions, owning and operating costs will be dramatically lower compared to the standard machine, and its carbon footprint will be smaller, the company said. Precisely when customers will recoup their initial investment in a 336E H depends on fuel prices and their applications. Assuming today’s fuel prices and a high-production application for a 336E H, Caterpillar estimates customers can realistically expect to see a return on their investment for the hybrid excavator model in as little as one year.

Caterpillar designed the 336E H to deliver the same durability and reliability customers expect of all Cat machines, including large excavators like the standard 336E. The design of the 336E H uses Cat hydraulic components with a long track record of proven durability and reliability for maximum uptime and productivity. Also like a standard machine, 336E H components can be replaced or rebuilt to maximize the hybrid’s service life.

Information for this article courtesy of Caterpillar.