NWT Investigates Hydraulic Hybrid Technology

NWT employees Bryan Roy and Paul Windover recently instrumented a Berkshire Regional Transit Authority shuttle bus in Pittsfield, Massachusetts with a vehicle data acquisition system. Ken Rocker and Matt Oesterling will monitor and analyze baseline operational performance data to determine the potential benefits of a series hydraulic hybrid system retrofit for this application. The operational performance data includes over 80 data fields being measured using NWT's data collection system, which consists of a datalogger, a CAN data-interlink using J1939 and J1708 protocols, and a cellular modem for transferring operational data back to a remote server. Over 20 data parameters are being recorded, including engine torque and speed, vehicle speed, fuel consumption, mileage, brake and accelerator pedal positions, engine coolant temperature, and truck GPS position.

This effort is part of a New York State Energy Research and Development Authority (NYSERDA) funded project to evaluate the commercial feasibility of Bosch Rexroth's series hydraulic hybrid technology on various light- and medium-duty applications. Hydraulic hybrid powertrain technology stores energy by pressurizing a gas in a hydraulic accumulator(s) rather than storing energy in batteries as is done in hybrid-electric vehicles. An engine-driven hydraulic pump and/or the regenerative braking capability of the hydraulic pump/motor (in pump mode) are used to charge the accumulator. The stored energy is delivered back to the hydraulic pump/motor (in motor mode) to drive the wheels. The shuttle bus evaluation follows other commercial vehicle application analyses for the technology, which included a NYC "black car" and parcel delivery vehicles. Two other shuttle buses were previously instrumented and monitored in Fairfax County, VA and Buffalo, NY.