|Components of the Eaton heavy-duty hydraulic launch assist (HLA) system. Click to enlarge.|
Waste Management, Inc., North America’s largest waste management company, is field-testing parallel hydraulic hybrid waste collection trucks. Four parallel hydraulic hybrid-diesel collection trucks have been incorporated into Waste Management’s fleet and are being tested in Fort Worth to study and optimize the hybrid system’s efficiency and reliability.
The four Peterbilt 320 vehicles in Fort Worth use the Eaton Hydraulic Launch Assist (HLA system). The HLA system can capture and store up to 75% of the energy normally lost as heat by the vehicle’s brakes in the form of pressurized hydraulic fluid. (Earlier post.)
The stored energy is then transferred to accelerate the vehicle to the next pickup location, reducing fuel consumption and wear on the engine. The HLA system provides 380 hp (283 kW) of power and 2,550 lb-ft (3,457 Nm) of torque.
Though hybrid technologies have been successfully deployed in automobiles and light trucks, Class 8 vocational vehicles, a category that includes waste trucks, pose additional challenges to hybrid design. Among the largest vehicles on the road, Class 8 vehicles require a robust drive train that can handle heavy loads, and have multiple systems for compaction and lifting that draw power from the engine, complicating hybrid design.
Eaton projects that the heavy-duty HLA system will result in a 28% fuel economy improvement when the truck is operating in economy mode, and 17% in productivity mode. Vehicle acceleration is projected to increase 2% in economy mode and 26% in productivity mode.
Eaton also suggests that the HLA system will deliver an 11.5% improvement in productivity cycle time, while more than doubling brake life.
The Peterbilt 320 HLA is equipped with a Caterpillar C-10 315 hp engine, and an Allison 4560 5-speed automatic transmission.
Eaton also supplies light- and medium-duty hydraulic hybrid systems; a hydraulic series hybrid system (now applied in UPS delivery trucks); and electric hybrid systems.
The HLA system is the first among many technologies Waste Management says that it expects to test and implement over the coming years.
We are working closely with a number of manufacturers to develop and test both hydraulic and electric hybrid systems for our fleet vehicles. The challenge for our engineering team is to make our vehicles as efficient as possible while also ensuring they are tough enough to withstand wear and tear on the road. Though development is in early stages, we are optimistic that the investment we are making now will lead to a reduction in greenhouse gases and ultimately benefit both manufacturers and users of heavy vocational vehicles.—Eric Woods, vice president of Fleet and Logistics for Waste Management
Waste Management operates one the largest commercial fleets. With annual fleet expenditures of up to $500 million, the company is in a unique position to spur innovation and efficiency. By creating demand for efficient vehicles, and supporting CAFE standards for heavy vehicles, Waste Management is encouraging technologies that will have broad benefits.
The hydraulic hybrid project is part of an initiative announced last year increase the fuel efficiency of its fleet by 15% and reduce fleet emissions by 15% by 2020.
Waste Management is testing a number of measures to achieve this goal. In addition to working with truck and engine manufacturers to test hybrid systems, the company is continuing to make its routes and fleets more efficient. Waste Management has been a pioneer in the waste industry in the use of LNG and CNG as an alternative fuel for its fleet and evaluating a wide range of technologies that could create fuel for vehicles from landfill gas, such as liquefied natural gas and synthetic diesel.
High Power, High Value, Hydraulic Hybrids (Eaton, 2008)