Hydro-mechanical Vehicle Transmission

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This hydromechanical automatic transmission provides hydraulic regenerative braking for cars, trucks and buses with an approx. 40% improvement in mpg at a total vehicle cost less than the equivalent conventional vehicle. It provides 60 separate forward gear ratios (approaching continuously variable).

It consists of 8 fixed displacement hydraulic pump/motors, two speed-reduction planetary gear sets and a selectable one-way clutch. Four input pumps drive 4 output motors. Different gear ratios are obtained by selectively deactivating the pumps and motors.

Its manufacturing cost is comparable to a conventional 8 speed automatic transmission. Its efficiency, reliability, size and noise are comparable to a conventional automatic transmission.

All that is required to convert a vehicle to a hydraulic hybrid is this transmission and an accumulator and reservoir.

This could be beneficially applied to all the world's road vehicles. Making a major dent in global warming.

A complete peer-reviewed description can be found in SAE paper 2014-01-1717.


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  • Name:
    Robert Lloyd
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  • Robert is inspired by:
    Global warming
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