The transmission group includes a hydraulic first switching mechanism inside the rear half of the forward traction machine casing (1). Th forward casing has an internal dividing wall (1a) and an open rear end. The switching mechanism is supported at the rear by a bearing frame (4) on the front casing.The transmission casing (2) contains a second switching mechanism similarly supported. A hydraulic pump to supply fluid to the first switching mechanism is mounted on the dividing wall. The bearing frame contains a fluid channel (162) to take fluid from the sump to the pump.
