Abstract: In a preferred embodiment, there is provided in series with one-another a plurality of the basic motor unit of the present invention, the basic unit including one or more electric motors in parallel for driving a hydraulic compressor feeding a piston cylinder provided with a piston shaft extending axially along the longitudinal axis of the piston cylinder for reciprocatable motion of the piston shaft which at the distal end thereof is connected to a rotary crank and by the reciprocatable motion revolves the crank to impart rotary motion to the gears of a gear box drivable of the gearbox output rotary shaft having an appropriate clutch and a take-off pulley driven by the rotary shaft, and further driving a next-occurring hydraulic compressor of a next basic motor unit in the series.