A hybrid powertrain system includes a first prime mover having an output, a multi-ratio transmission having an input, and a second prime mover having an output connected to the first prime mover output through a first power path and to the transmission input through a second power path. The first power path receives power from the second prime mover during a first operating mode to drive rotation of the transmission input and the second power path receives power from the second prime mover during a second operating mode to drive rotation of the first prime mover output. The second prime mover output is configured to rotate in a first direction in the first operating mode to transmit power to the first power path and in a second direction in the second operating mode to transmit power to the second power path.