The analysis of hydrostatic hybrid technology is on the rise in several cities across the United States, as several of the major fluid power providers team with businesses and major metropolitan areas to curb the reliance of oil-based products in vehicles.

In yet another such move, Bosch Rexroth Corp., Hoffman Estates, Ill., has been selected by New York-based Shurepower LLC to demonstrate hydraulic hybrid vehicle technology by installing a Rexroth hydrostatic regenerative brake (HRB) system onto refuse trucks that will undergo field tests in New York City and Baltimore. The project is sponsored by the New York State Energy Research and Development Authority and the National Association of State Energy Officials.

Details outlined
The project aims to assist widespread application of hydraulic hybrid powertrains in vehicle fleets, such as refuse haulers. They have high potential for successfully using this technology to reduce fuel consumption and emissions, along with lowering operating and maintenance costs and improving performance.

The Department of Sanitation-New York City and the City of Baltimore Bureau of Solid Waste will host the field tests. Each city will be provided a prototype truck chassis from American LaFrance LLC. The HRB system will be installed in this chassis.

The Rexroth HRB system uses a hydraulic pump/motor, connected to the driveline, to capture kinetic energy during vehicle braking. This energy would otherwise be lost as heat in the vehicle's friction brakes.

When braking, the HRB absorbs energy from the driveline, imparts a retarding force on the drivewheels, and uses the absorbed energy to pump hydraulic fluid into an accumulator. During acceleration, pressurized gas pushes fluid out of the accumulator, and the pump/motor now acts as a hydraulic motor, assisting the engine and reducing the fuel required to launch the vehicle.

Why hydraulics?
Hydraulic hybrids offer the potential for significant reductions in fuel consumption, emissions, and brake wear. Compared to hybrid electric powertrains now entering the market, hydraulic hybrids appear to be inherently better suited for the very high power-handling requirements encountered during regenerative braking, and they require fewer efficiency-robbing energy conversion steps.

These factors indicate that hydraulic hybrids have the potential to capture a larger portion of the braking energy and to use the captured energy more efficiently. In addition, the required types of hydraulic components enjoy the benefit of many years of development, refinement, and successful application to a wide variety of industrial and mobile power markets, where they have established a reputation for ruggedness and durability.

For more information, visit www.boschrexroth-us.com.