Loveland, Colorado – Two U.S. companies are partnering on hydraulic hybrid retrofit systems for trucks, using a hydraulic motor in place of an electric motor, and a pressurized tank in place of the batteries used in a conventional hybrid vehicle.

Hydraulic Hybrid Systems (HHS) has partnered with Equipment Maintenance Innovators (EMI-Global) to manufacture and distribute retrofit systems for light- and medium-duty fleet vehicles. The company said that the systems can improve fuel mileage by more than 40 per cent over a regular vehicle, and greatly reduce greenhouse gas emissions. A retrofit system for a Chevrolet 2500/3500 gasoline or diesel vehicle would cost about US$12,900.

“Hydraulic hybrids have been around for a while, but there has been no reason until now to explore these kinds of technologies,” said Richard LeFrancois, president of EMI-Global. “Now is the time to move forward with hydraulics because of the push to cut emissions and dependence on foreign oil. Batteries just cannot address issues for fleets at the scale that we need.”

Denver International Airport has provided the first truck to be retrofitted, a Chevrolet heavy-duty 2500 fuelled by compressed natural gas. The system is currently being installed and tested, and the truck prototype will be put into runway service in early October 2009.

HHS first showed a prototype system at the Denver Auto Show in 2009, where it received interest from fleet managers about applying the hydraulic hybrid as a retrofit to existing vehicles. “We explored the opportunity and found a need for fuel and emissions savings in the light-duty fleet market,” said Dan Johnson, CEO of HHS. “A hydraulic hybrid retrofit system is an excellent answer in situations where the light-duty fleet vehicle does a lot of start and stop driving, such as city and state fleet vehicles, vocational and contractor trucks and vans, mining and oil field vehicles, and school buses.”

Although HHS is currently the only provider of retrofits and systems for light-duty vehicles, these hybrids are already available from several manufacturers for new heavy-duty trucks, and the U.S. Environmental Protection Agency has developed and tested hydraulic hybrid vehicles in the past. In a parallel hydraulic system, a hydraulic motor/pump acts in place of the electric motor in an electric hybrid, and a hydraulic accumulator tank pressurized to 5,000 psi acts in place of the batteries. The company said that compared to an electric hybrid system, hydraulic hybrid systems are much safer and less expensive to maintain.

Connect with Autos.ca