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Video: Cat’s hybrid excavator tech explained

Following on from our report on Caterpillar’s hybrid technology, in this video Cat Hydraulic Excavator Product Application Specialist Kit Kyarsgaard explains the workings of the hydraulic-based system as he takes us around the 336E LH excavator.

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The base machine is a standard 336E excavator, Kyarsgaard says, so there’s commonality in the bucket, the coupler, the stick, the booms, the upper structure, the lower structure and so on. This makes it easier to get parts and keep the machine making money.

But there are some obvious differences under the hood, where you find Cat’s hybrid technology.

As we explained here, Cat uses three pieces of hybrid technology that work together: the Cat Hydraulic Hybrid Swing System, which uses nitrogen-filled accumulators to capture the excavator’s swing brake energy then reuse that energy during swing acceleration; the Adaptive Control System (ACS) valve, which controls and optimises the motion of the excavator by managing restrictions and flows; and the Electronic Standardized Programmable (ESP) pump, which transitions between the hydraulic hybrid power sources, engine and accumulator and reduces the engine load as much as possible to save fuel.

After the walkaround, Caterpillar Asia Pacific General Manager Sales & Marketing Phillip Pollock told us that we could expect to see hybrid technology rolling out up the chain of bigger excavators in the future, but not down.

“It will naturally go up the chain, particularly on 74 or 90-tonne excavators,” Pollock told us. “The 374 and 390F today already have elements of building blocks from the hybrid back into those platforms”, such as ACS and the new pump.

“We’re getting eight to 10 percent fuel efficiency improvement — or consumption improvements — on those models straight away,” he added. The bigger the machine the more fuel you use, he said, so the greater the savings.

However, elements of the building blocks of the hybrid system will continue to thread themselves through the smaller machines, Pollock said: “As it goes down I think you’ll find it will be more related to systems efficiencies through ACS, through hydraulic lines routed to remove inefficiencies, rather than bringing an energy-recovery system into, say, a 14-tonne excavator, because the contractor … is not burning the fuel required to get the return on investment.”

Payback from the premium paid for the hybrid portion of the machines is in as little as two years, Kyarsgaard said.

“It could be less than that, depending on the hours and machine efficiencies,” he added. “You can get it down to a year if you have a very, very high production double-shifting, but on average it’s about two years.”


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