Abstract: Power transmission apparatus having a torque convertor with an input shaft, an impeller connected to the input shaft, an output turbine, a first uni-directional detent, a reactor connected to a fixed part on which to react by means of the first uni-directional detent which is arranged to prevent rotation of the reactor in a reverse direction, a circulatory turbine, a first gearing connecting the circulatory turbine to the input shaft, a second gearing connecting the first gearing to an output shaft, a second uni-directional detent, and a brake arranged to act between part of the second gearing and a stationary part. The apparatus also includes a ring gear and a holding device acting on the ring gear, both being included in the second gearing, so that when the ring gear is held stationary by the holding device, the output shaft is driven in reverse.

Abstract: The invention provides a power transmission apparatus which includes a hydraulic torque converter and mechanical gears. The torque converter includes a circulatory turbine in addition to the usual output turbine. The mechanical gears include first, second and third gearings. The first gearing connects the circulatory turbine to the converter input shaft. The second gearing connects the first gearing to the converter output member through a unidirectional freewheel. The third gearing connects the second gearing to an output member of the apparatus.