Peterbilt Model 320 Hybrid HLAs are being put to use in Ann Arbor, MI, where they will serve as recycling trucks. | Photo Courtesy of Peterbilt Motors Company
Hydraulics in vehicles — best known for bouncing cars and kneeling buses — are getting a serious look in Ann Arbor, Mich. The reasons — saving fuel and increasing the life of heavy-use vehicles.
With the support of a $120,000 Recovery Act grant, Ann Arbor, Mich., deployed four recycling trucks with hydraulic hybrid power systems implemented by Ohio-based Eaton Corporation. For these trucks, which make up to 1,200 stops each day, the Hydraulic Launch Assist (HLA) systems provide an improvement in fuel economy and emissions of up to 30 percent and significantly reduces maintenance costs.
"Ann Arbor likes to be at the forefront of new technology," says Tom Gibbons, a city financial analyst for fleet and facilities. "We have a green fleet policy that gives us permission to spend up to 20 percent extra on a vehicle if it's more fuel-efficient and environmentally friendly. When we got the grant to cover the costs for the new technology, it clinched the deal for us."
The city received a $120,000 Clean Cities Recovery Act award to help offset the cost of purchasing the HLA trucks. The funding was secured by the Clean Energy Coalition (CEC). The CEC evolved from an environmental organization the city helped create and has expertise in writing grant applications, so Ann Arbor worked with the group to develop an effective presentation. The group is part of the Clean Cities Coalition, an initiative of the U.S. Department of Energy's Vehicle Technologies Program, which provides technical assistance to local coalitions on alternative fuel and fuel-efficient vehicles.
Ann Arbor was already planning to implement a new recycling program that involved purchasing the four trucks, priced at about $300,000 each. But the added cost of the HLA system for each truck, which will save 30 percent on fuel costs in the long run, was covered by the grant money. The city expects the trucks to be in service for a decade.
Technology fueling maintenance cost reductions
The HLA technology works by capturing the trucks' kinetic energy during braking to assist with powering the vehicle. The HLA recovers up to 75 percent of the energy normally lost as heat by the vehicle's brakes in the form of pressurized hydraulic fluid.
The hydraulic fluid is stored on-board until the driver next accelerates the vehicle, at which point hydraulics provide an extra power boost. Tests on the HLA technology have shown that wear on both the engine and brakes can be significantly reduced with its use — brakes last four times as long, compared to a similar truck without HLA. That reduction in maintenance will add up to about $100,000 over the life of the trucks for Ann Arbor, in addition to the fuel savings. Each of the new recycling trucks will make an estimated 1,200 stops daily to pick up recyclables.The trucks have been in service about two months so far.
"The drivers don't notice any difference," Gibbons says. "Well, other than they stop a lot more quickly when take their foot off the gas pedal."