The New York City Department of Sanitation (DSNY) will be testing in daily operation three different types of hybrid refuse collection trucks and a hybrid rack truck. The trucks were unveiled at the Parks & Recreation Department’s 21st Annual Vehicle & Equipment Show in Flushing Meadows-Corona Park in Queens.
The vehicles under evaluation include a parallel hybrid electric diesel collector from Mack Trucks (a Volvo Group subsidiary); a series-hybrid and an hydraulic parallel hybrid collector (earlier post) from Crane Carrier; and the Kenworth T370 diesel-electric hybrid (for the rack truck).
The Mack TerraPro Low Entry model refuse truck is the first parallel hybrid-electric diesel truck in the country designed specifically for Class 8 heavy-duty applications. The TerraPro hybrid has a rear-loading refuse packer body. It is equipped with a 325 hp Mack MP7 engine and Selective Catalytic Reduction (SCR) exhaust aftertreatment technology, the approach that Mack is utilizing to meet US Environmental Protection Agency’s near-zero emissions standards for 2010.
The Mack diesel-electric hybrid powertrain used in the truck features an integrated starter, alternator and electric motor. (Earlier post.) The system captures energy from braking, converts the energy to electricity, stores the electricity in lithium-ion batteries, and uses it to power the electric motor, which assists the MP7 diesel engine with propulsion of the truck. As a result of the hybrid operation, in which an electric motor and a diesel engine work in parallel, fuel consumption can be reduced by up to 30% and carbon emissions decreased to the same extent.
When the vehicle is first started, only the electric motor is used; the diesel engine starts operating when the vehicle has reached a certain speed. To date, the Volvo Group has developed some 20 vehicles including refuse collection vehicles, buses and wheel loaders, which use the Group’s parallel-hybrid solution. The base technology is standardized but adaptable and can thus be used in many different commercial vehicles, which reduces production costs when manufacturing in large volumes.
The Crane Carrier Corporation Bosch Rexroth Hydrostatic Regenerative Braking (HRB) parallel hydraulic system uses a hydraulic pump/motor coupled to the mechanical drive train through a gearbox. When braking, the pump/motor acts as a pump, absorbs energy from the driveline and imparts a retarding force on the drivewheels, pumping hydraulic fluid into a nitrogen-pressurized accumulator. Fuel savings are projected at 25%.
The Crane Carrier ISE series hybrid-electric diesel rear-loading collection truck is the first of three ISE series hybrids to be delivered to DSNY. The DSNY hybrid pilot vehicles utilize ISE’s hybrid electric drive system which is self-contained in three separate modules that are mounted on board the truck chassis.
The ISE diesel hybrid system combines a 5.9-liter Cummins ISB engine and 120 kW generator with two 150 kW drive motors with combining gearbox from Siemens. (Power electronics are from Siemens as well). Energy storage is a 288 cell ultracapacitor system.
The hybrid drive cabinet with ultracapacitor energy storage and overall system controls, together with the engine driven generator assembly, are mounted behind the cab. The electric traction motor is mounted between the frame rails of the truck chassis and takes the place of the conventional transmission in the vehicle.
ISE’s proprietary ultracapacitor packs store energy recovered from frequent braking cycles experienced by the refuse collection vehicles during normal operation. The refuse vehicles are also equipped with ISE’s onboard Remote Diagnostics System (RDS), which includes GPS and allows for real time performance monitoring through a web-based interface. ISE’s series hybrid electric vehicle is also capable of providing emergency backup power and could eventually have a plug-in feature enabling Vehicle-to-Grid capability.
The Kenworth T370 diesel-electric hybrid truck is the first medium-duty hybrid truck to enter service in DSNY’s fleet. The T370 Class 7 is powered by the PACCAR 6.7-liter PX-6 engine, which is rated at 300 hp (224 kW) and Eaton’s medium-duty hybrid system with a parallel, pre-transmission design. (Earlier post.) A 2 kWh Li-ion pack provides energy storage.
Kenworth’s goal for the T370 hybrid tractor is to improve fuel economy by up to 25% in local haul applications.