When one thinks of hybrids, cars like the Toyota Prius come to mind. There’s no reason though green vehicle technology like this needs to be limited to passenger cars or commercial vehicles like moving trucks. It is also turning up in the construction industry, in part via the unveiling in the last week of a new hybrid excavator from Caterpillar.
Caterpillar said its new Cat 336E H is a derivative of the company’s 336E large hydraulic excavator, which is described as a “recognized industry-leading workhorse” by its manufacturer. The new hybrid version is the company’s first to make use of what it calls “a novel hydraulic hybrid technology developed internally” that reportedly uses 25 percent less fuel compared to its regular sibling. Torque News noted of this machine that it has a drive train that “is a diesel-electric design but Caterpillar is not describing the electrical storage capacity nor power of the electric motor.”
So what exactly does a construction equipment manufacturer define as a hybrid? Caterpillar looks at it as a construction machine that is equipped with “a device to collect, store and release energy during machine operation.” In the case of the 336E H it is designed to capture energy “when the machine slows down or stops, and then releases it as the machine accelerates” via a form of regenerative braking tied to the excavator’s upper structure swing brake. More specifically, this technology puts the energy collected in accumulators, and then releases it during swing acceleration.
On a typical job site, Caterpillar noted, “an excavator may repeat the same cycle every several seconds, which represents a significant energy savings opportunity.”
In addition to the regenerative braking, the 336E H has a fuel conservation pump that helps transitions between the hydraulic hybrid power sources, engine and accumulator as well as a special valve that “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.”
The company said it has tested electric hybrid excavators in the past, but until now “had not found a hybrid approach that would actually lower our customers’ owning and operating costs.” In terms of estimated return on hybrid investment, when you consider this machinery will likely cost more up front than a regular 336E, Caterpillar noted this will depend upon current fuel prices and how the 336E H is used. In one scenario put forth, assuming today’s fuel prices and a “high production application” of the machine, one might expect to recoup the extra expense in fuel savings in “as little as one year.”
In addition to the fuel savings, the 336E H is also said to meet “stringent Tier 4 Interim/Stage IIIB emission standards” and also run much quieter than other excavators. Caterpillar, which describes its new hybrid as a “socially responsible” machine (which may be stretching it), will begin taking orders in February, delivering them one month later.
So, if you are looking for a giant green technology construction toy to play with, the 336E H might be it. Just make sure you have a big enough sandbox to fit it in.
By Nino Marchetti