The first hydraulic hybrid package delivery vans produced for regular service are now in the hands of three major fleets for evaluations, according to the Hybrid, Electric and Advanced Truck Users Forum (HTUF).

The walk-in vans were assembled by Freightliner Custom Chassis Corporation (FCCC) with bodies by Morgan Olson and drivetrain components from Parker Hannifin. HTUF noted that previously produced hybrids use electric drivetrains, and that hydraulic versions are alternatives that might hold operational and cost advantages.

FedEx Ground, Purolator, and United Parcel Service each have one of the trucks, purchased with grants from the U.S. Department of Energy administered through CalStart, a management and advocacy group headquartered in Pasadena, Calif. The three fleets are members of HTUF's Parcel Delivery Working Group.

"Parker is excited to deploy our first three hydraulic hybrid drive systems with the CALSTART-led HTUF Working Group. After recent EPA testing, Parker's system came out best in class compared to similar hybrid systems. We are anxiously waiting to see real world test results from our three customers," said Shane Terblanche, general manager of Parker's Hybrid Drive Systems Division.

The Parker system in these trucks is designed for medium duty, start-stop applications, he said. Advancing upon Parker's RunWise heavy duty system presently available for refuse applications, this midrange version incorporates an infinitely variable transmission.

Braking energy is recovered and stored in hydraulic accumulators, where it is used to power the truck during acceleration, the company said.
Power from Parker's hydraulic pump/motors and accumulators is blended with engine power depending on driver demand.

Parker's onboard controller uses an advanced engine-off strategy to minimize unnecessary run time. Thus fuel use can be reduced by 40% or more, depending on route profile.

UPS previously tested hydraulic hybrids, said Mike Britt, director of vehicle engineering. So "we are optimistic that this new technology will perform as well as it did in the test vehicles, improving fuel economy and reducing emissions."

The three package delivery companies will be cooperating with CalStart and FCCC to gather data on the operation of the vehicles to establish expected fuel economy improvements and reduced brake and engine maintenance costs.

Although hydraulic hybrid systems have shown promise over the last few years, commercial deployment of these systems has been limited to Class 8 refuse trucks, HTUF said. This evaluation will assess a hydraulic hybrid system for the lighter, Class 6 vehicle applications.

Successful demonstration could lead to additional purchases of hydraulic hybrid vehicles throughout the trucking industry, the group believes.