At ">Bauma, Hyundai displayed its own hydraulic hybrid, called Hi-POSS, that is slated for production next year. Liebherr also showed a concept excavator, which has an electric-hybrid swing drive and a hydraulic-hybrid boom circuit.

Excavators are not the only machines to incorporate hybrid-hydraulic power; trash and delivery trucks are starting to use it. Liebherr also is rolling out its HS-8100HD, a 330-ton crawler crane; its Pactronic hoist drums power a hydraulic-hybrid circuit that pumps up accumulators when gravity pulls against the hook.

This allows Liebherr to run the V-12 diesel engine at a constant speed of 1,800 rpm—as opposed to the typical 900 to 2,200 rpm—as well as push more power to the hoist line. Designed for duty-cycle work that usually runs at 200 ft per minute, the hybrid crane can achieve almost 400 fpm while reducing fuel use by 15%. The $6-million machine comes at a price premium of about 10%.

"It is fuel-consumption reduction and additional power, so it fits the market requirements," said Joachim Kern, product manager for Liebherr, which already has used this concept on harbor cranes. Eventually, Pactronic will come to all Liebherr duty-cycle cranes, Kern noted.

Marketing hybrids to a traditionally conservative user group is still a challenge. Hydraulics may pay back faster than electrics, but the sales risks are the same. "It's fear of the unknown," said Gray.