The invention relates to a power train for a hybrid motor vehicle, including a heat engine (34), as well as a hydraulic machine (2) and a hydraulic pump (64) which can be connected via a hydraulic circuit to high pressure accumulators (72), wherein said power train also includes a transmission comprising an output differential (20) connected directly to the hydraulic machine, and a planetary gear (30) having an outer ring gear (32), a planet carrier (40) and a sun gear (36), wherein said planet carrier is connected to the differential, and the ring gear and the sun gear are each connected to the heat engine and to the pump, respectively, characterized in that the hydraulic circuit comprises controlled means that form a direct passage (78) between the pump (64) and the hydraulic machine (2), and a closure (76) for the high pressure accumulators (72).