The smell of garbage may be far from pleasant, but saving fuel and reducing emissions sure is sweet. Bosch Rexroth Corp., Hoffman Estates, Ill., has been selected by CALSTART’s Hybrid Truck Users Forum (HTUF) Refuse Working Group to examine and test the use of hybrid vehicle technology in refuse trucks. Rexroth will contribute its Hydrostatic Regenerative Brake (HRB) parallel hydraulic hybrid system to the project, which will be deployed and tested in The Big Apple.

Bosch Rexroth, Crane Carrier Co., and ISE Corp. make up the supplier team for the HTUF project. During testing, the hybrid trucks are expected to demonstrate between 30% and 50% reductions in fuel and emissions use. The field tests are designed to authenticate both the technical and economical characteristics of the HRB system. The hope is that the results will demonstrate HRB’s potential, eventually leading to large-scale deployment of existing and new vehicles.

The HRB system uses a hydraulic pump/motor, connected to the driveline, to capture kinetic energy during vehicle braking. When braking, the pump/motor acts as a pump, absorbing energy from the driveline and imparting a retarding force on the drivewheels. It then uses the absorbed energy to pump hydraulic fluid into a nitrogen-pressurized accumulator. The accumulator is a tank containing inert gas that is compressed by the incoming fluid. During acceleration the pressurized gas pushes fluid out of the accumulator and the pump/motor then acts as a hydraulic motor, assisting the engine and reducing the fuel required to launch the vehicle. The overall process is referred to as regenerative braking.

The HRB system will power the Crane Carrier LET2 chassis in the trucks, and will be integrated with the Heil refuse body hydraulic system for weight savings and efficient packaging. Hydraulic hybrids are better equipped to cope with the extremely high power-handling requirements of regenerative braking, and they require fewer energy conversion steps that reduce efficiency. In this way, hybrid systems have the potential to capture a larger portion of the braking energy and make use of it more effectively.

Visit Bosch Rexroth for more information.

To see a video clip of this technology in action, click here.