Eaton recently discontinued its Hydraulic Launch Assist system, which was a parallel hydraulic hybrid. That leaves the RunWise Advanced Series Hybrid drive system from Parker to serve the refuse market, where both systems had built up some market share.

Eaton's Hydraulic Launch Assist hydraulic hybrid system, often referred to as a mild hybrid rather than a full hybrid, offered energy recovery of up to 70-80%, and fuel savings on the order of 4 to 5 gallons of fuel per day with an ROI of 2 1/2 to 5 years, Eaton said. That apparently wasn't enough.

Recently, Eaton quietly withdrew its HLA system from the market, leaving Parker's RunWise system as the sole player in the refuse market.

In early 2010, Eaton announced it was signing up independent service partners to begin installing retrofit versions of its HLA hybrid power system for refuse trucks. 

As recently as last fall at the HTUF annual meeting, Peterbilt Motors and Crane Carrier Corp. showed trash collection models fitted with an improved Eaton Hydraulic Launch Assist drive system, which did a better job of blending the hydraulic regenerative and foundation brakes.

Peterbilt was a supporter of the HLA technology, offering it in its Model 320 low-cab-forward.

"While the HLA system is no longer available, Peterbilt continues to offer fuel-saving options for its Model 320, such as LNG and CNG configurations of the Cummins Westport ISL-G and ISX12G," said a Peterbilt spokesman in response to our question about the fate of the HLA system. "Of course, for this model we also offer the Paccar PX-9 and Cummins ISX12 diesel engines, which can both be optimized for fuel efficiency in relation to the customers' applications."

Runwise

That leaves the market with Parker's system. RunWise is a full hydraulic hybrid power system offering regenerative braking as well as a full time hydrostatic drive. The company claims, and customer testimonials seem to bear out, that it could save up to 20-30 gallons of fuel in a day – approximately a 50% reduction in fuel consumption, depending on the duty cycle.

With natural gas quickly becoming the dominant fuel in the refuse sector, where supply infrastructure exists, its reduced cost and carbon emissions have changed the business case for mild hydraulic hybrids.

Eaton declined to be interviewed for this story, but told HDT that since CNG began taking over all new investments in refuse, hybrids are no longer serious contenders.

Read more about hydraulic hybrids and other alternative fuels and powertrains in the September issue of HDT.