Abstract: An electro-mechanical vehicle power transmission (10) comprises two planetary trains (12, 14) defining mechanical pathways, two electric machines (20, 22) defining an electrical pathway, and at least one torque transfer device (24) that can selectively couple between one component and another component or components mm to transfer torque. Each planetary train includes a sun member (12A, 14A), a ring member (12B, 14B), and a plurality of planet members (12C, 14C) engaged with the ring member and the sun member. Each planetary train includes a planet carrier (12D, 14D) configured to hold the planet members in an annular space between the ring member and the sun members. Each electric machine can be operated either as a motor to covert electrical energy to mechanical energy or as a generator to convert mechanic energy to electric energy.