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.”