Hydraulic Hybrid Vehicle Technology

https://www.youtube.com/watch?feature=player_embedded&v=FpthKavtSSo

The U.S. EPA owns the patent rights to the hydraulic hybrid technology explained in this video. Fedex has licensed the technology and uses it in many of their delivery vehicles.

The US EPA claims that in laboratory tests, the city fuel economy of an urban delivery truck was 60%-70% increased miles per gallon versus a similar, conventionally powered internal combustion truck.The CO2 emissions of the same demonstration delivery truck were claimed to be over 40% lower, and the hydrocarbon and particulate matter production were also much lower (50% and 60% respectively).

The EPA calculated for this test vehicle, the hybrid technology added a cost of about US$7,000 over a comparable conventional truck, while the lifetime fuel savings over 20 years were estimated above $50,000

Here is a brief summary of how it works.
When the driver’s pedal is pressed, pressurized nitrogen stored in the high pressure tank pushes fluid through the pump motor using the pressure to turn the wheels. The now non pressurized fluid is stored in the low pressure tank. When the vehicle is cruising and the use of high pressure fluid drops beneath a certain level the engine turns on.
The engine is connected to a hydraulic pump which pressurizes the low temperature fluid for the pump motor to continue to turn the wheels. When the brake pedal is pushed the pump motor slows the vehicle down by using the vehicles kinetic energy to pressurize fluid, pumping it back to the high pressure tank.
When the driver wants to accelerate again only the saved energy will be used to turn the wheels.
Enjoy the video and ask yourself why we are not using this technology for large trucks.