The Environmental Protection Agency (EPA) announced the establishment of tests of a hydraulic transmission system associated with an internal combustion engine, supposed to be more economical and less polluting.
Based on EPA technology, the Eaton Group (Ohio) will replace the mechanical transmission of a UPS carrier vehicle with a device to transfer the
power through a hydraulic tank under pressure. In practice, the pressure of approximately 3500 tonnes per square meter, created by the diesel engine running at a constant speed, makes it possible to drive the rotation of a turbine and thus that of the wheels - the speed of the vehicle being controlled by the pressure released. in the turbine. This pressure can be accumulated, which amounts to storing energy. The principle also benefits from a recovery of power during braking. This phenomenon, called "regenerative braking", exists for hybrid electric cars but with an efficiency of 35 to 40% against almost 75% announced for the hydraulic system.
Preliminary laboratory tests would, according to the EPA, show a potential fuel saving from 60 to 70% for non-steady operation (unstable speed). Field trials are therefore eagerly awaited by the project sponsors,
which the US Army. But the approach does not seem to be unanimous. Ford for its part abandoned this direction to focus on hybrid vehicles.
NYT 10 / 02 / 05 (Test set on transmission that could save fuel)