VIDEO: Hybrid Excavators – the Cat 336EL

I like diggers, so here’s a video of Hybrid Excavator.

This was a world’s first by CAT in 2012, and started shipping earlier this year. Industrial vehicles such as this are are subject to EU Directives on emissions from non-road mobile machinery, and the 2010 Stage IV amendment which would cover the 336E comes in to force in January 2014, as well as the US Clean Air Act (CAA) amendment.

CAT mention fuel saving as the primary driver, but while that is probably a major selling point, it’s also a fact that the manufacturers like Cat need to find ways to meet the new emissions restrictions for new vehicles if they want to be able to sell them – this is one such innovation.

This isn’t an electric hybrid, it uses Hydraulic accumulators to store energy – each time the bucket arm swings and brakes, the braking energy is used to pressurize Hydraulic fluid, which is then fed back in to the system with a special valve system – excavators spend a lot of time swing-loading, and the efficiency gains are claimed to be as high as 30%.

More about the Cat 336EL:

“A hybrid is independent of any particular technology—it doesn’t have to be electric… …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… …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. 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”
Ken Gray, Global Product Manager, Caterpillar Excavation

“The 336E H is a game-changer—the most revolutionary excavator to come to market in decades… …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 our industry leader, the 336E. Caterpillar has the most productive and fuel-efficient excavator product line in the industry.”
Gary Stampanato, VP, Caterpillar Excavation


  • 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.


CAT 336EL website

EU directives on Emissions from non-road mobile machinery

US EPA Nonroad Compression-Ignition Engines – Exhaust Emission Standards

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