Parker commercialises hydraulic hybrid system

A grant by the United States Department of Energy's Clean Cities program saw Daimler Trucks support the purchase of 638 hybrid and alternative fuel vehicles. "This is a significant development in the advancement of this new hydraulic hybrid system," said Don Washkewicz, Chairman, CEO and President of Parker. "The commercial application of our technology is recognition that our system has demonstrated several unique advantages over electric hybrids including significantly better fuel efficiency." Field testing of the system during the past year has indicated that the hydraulic system is capable of generating as much as a 50 to 70% increase in miles per gallon in stop-and-go applications when compared with traditional diesel powered vehicles that have automatic transmissions. The series hydraulic hybrid system is unique in that the engine is not connected to the rear wheels of the vehicle. This de-coupling of the engine from the drive wheels offers several advantages including the ability to recover and store energy from braking, thus reducing brake wear. An engine management system optimises the vehicles engine for reduced fuel consumption allowing the vehicle to be drive even with the engine off, significantly reducing carbon emissions in depots and at delivery points. Dr. Joe Kovach, Group Vice President of Technology and Innovation for Parker's Hydraulics Group, said: "We believe the series hydraulic hybrid technology has application not only in delivery vehicles, but also for yard hostlers and city buses. Additionally, our advanced series hydraulic hybrid system, called RunWise, is currently being field tested in more demanding applications such as with refuse vehicles. This is a technology that holds great promise as a contributor to reduced environmental impact and increased fuel efficiency." The Parker series hydraulic hybrid system stores energy recovered during the braking process in an advanced accumulator. The energy stored in the accumulator is then used to accelerate the vehicle on the next launch. Once that energy is depleted, the engine is restarted. Unlike electric-hybrid systems which store energy in a battery, the series hydraulic hybrid can recover and reuse as much as 70% of the braking energy that otherwise would be lost. By comparison, traditional electric systems can recover only 20 to 25% of brake energy.