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Cat Hybrid Excavator Focuses on Fuel-Savings


The new Cat 336E H excavator centers on an innovative, fuel-saving “hydraulic hybrid” system that captures and reuses energy. The machine was given a proper introduction to the market at a special April product launch in Peoria, Ill., attended by Rock Products Assistant Editor Josephine Smith.

Greater fuel efficiency is the net result – as much as 50 percent greater than the 336D. The benefits include lower fuel costs, reduced exhaust emissions and a smaller carbon footprint – all without any compromise in production, reliability, durability or operability in all applications.

The 336E H was unveiled in October 2012, and its order board opened this February with factory shipments beginning in March. According to Ken Gray, global product manager for large hydraulic excavators for Caterpillar’s Excavation Division, customers have shown tremendous enthusiasm for the 336E H since the day it was unveiled. “Customer interest has been off the charts,” Gray said. “They’re not only reaching out to Cat dealers to learn more about the 336E H, they are placing orders.”

Gray also said customers want to know about Caterpillar’s plans for expanding hybrid technology to additional excavators. “We’re getting a lot of questions about what other models will be available as a hybrid, and when,” said Gray. “While I will not divulge our full hybrid strategy, I will say we will have two additional hydraulic hybrid models, the 336F H and 336D H, on the way.”

Both the 336F H and 336D H models will have the same hybrid Cat Electronic Standardized Programmable (ESP) pump as the 336E H. The 336F H will feature a Cat C9.3 ACERT engine that meets Tier 4 Final/Stage IV emissions standards; the 336D H will feature a Cat C9 ACERT engine designed to meet the needs of customers in those countries with emissions standards different than Tier 4 Final/Stage IV.

We have active development programs for the machines, which will follow those two,” Gray said. “And we will continue to add appropriate hybrid technology to models where it adds value for customers – where it lowers owning and operating costs to help their businesses succeed. Our objective is to ensure our customers make more money with Cat products than they can with others.

Reduces Owning, Operating Costs
According to Gray, no other commercially available technology has higher power density than hydraulics, and that’s why Caterpillar selected a hydraulic solution to help its customers achieve substantial fuel savings.

“We leveraged our standard Cat hydraulic components to take advantage of economies of scale across our product line, which in turn significantly reduces the cost for our customers to own the 336E H. Plus they sacrifice nothing in terms of reliability, performance, power, force, speed or production,” said Gray. “And it is surprisingly quiet.”

Caterpillar, www.cat.com


Fuel Savings

To achieve fuel savings, the design of the new caterpillar 336E H is relatively straightforward, using three building block technologies:

  • Conserve fuel with engine power management via the Cat Electronic Standardized Programmable (ESP) pump.
  • Optimize performance using restriction management via the patented Cat Adaptive Control System (ACS) valve.
  • Reuse energy via the hydraulic hybrid swing, which captures the excavator’s upper structure swing brake energy in accumulators and then releases the energy during swing acceleration.

Customers can expect the 336E H to use up to 25 percent less fuel compared to a standard 336E and up to a 50 percent improvement in fuel efficiency compared to a 336D in a wide variety of operating conditions. All three of the technology building blocks, Conserve, Optimize and Reuse, are integrated together to maximize fuel savings in a variety of applications.

Precisely when customers will recoup their initial investment in a 336E H depends on fuel prices, a customer’s specific application and the number of hours the machine operates in a year. Assuming today’s fuel prices and a 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, with 18 months as typical.