Torque converters

Power transmission apparatus comprising a torque converter having an input shaft, an impeller connected to the input shaft, an output turbine, a reactor and a circulatory turbine disposed in the flow path between the impeller and output turbine, a first gearing connecting the circulatory turbine to the input shaft so that the said circulatory turbine will always rotate with and in the same direction as the said impeller, a second gearing connecting the first gearing to the output shaft and to a stationary part, said second gearing including a part which is acted on by a friction brake so that it can be connected with or disconnected from said stationary part, said second gearing including an internally toothed ring gear acted on by said second gearing brake, a sunwheel, and pinions meshing with the ring gear and the sunwheel, the first unidirectional detent acting between a part of the second gearing and said stationary part, and the second unidirectional detent acting between the reactor and the second gearing, said sunwheel being connected to each of said detents, said detents being in series so that forwards rotation of a part of the second gearing drives the reactor in a forwards direction and negative torque on either the reactor or said part of the second gearing can act on said stationary part.