Known as the 'series hybrid hydraulic system', Eaton has revealed the new technology is being developed jointly with the Environmental Protection Agency under a Cooperative Research and Development agreement, giving the company some credibility in its claims.
Eaton explained that in a series hybrid hydraulic system, the conventional transmission and driveline in a vehicle are replaced by a hybrid hydraulic powertrain, which allows energy to be transferred from the engine to the drive wheels through fluid power.
The vehicle uses hydraulic pump/motors and hydraulic storage tanks to recover and store energy, similar to what is done with electric motors and batteries in hybrid electric vehicles. In a series hybrid hydraulic system, Eaton claims that fuel economy improvements of between 50 and 70% are achieved in three ways - through utilization of braking energy that normally is wasted, more efficient engine operation and a stop/start system for the engine when it is not in use.
The system combines a high-efficiency diesel engine with its hydraulic propulsion system and uses a continuously variable transmission in order to keep the fuel consumption levels at a minimum. Consumer applications for the technology are currently still under development, however the system is expected to be trialled in a number of UPS trucks sometime next year.