The four branch differential Transmission System, ("FBD"), comprises a
first input shaft and a second output shaft. Furthermore there are third
and fourth shafts which are respectively connected to first and second
variators which control the speed (or torque) of the shaft, to which they
are connected. Each variator can, for instance, be an electric motor
which can adjust the speed of these shafts. The four shafts (branches) of
the FBD are connected directly or indirectly via gears. The FBD comprises
spur gear planetary gearsets. There is no requirement for a ring gear.
The FBD includes two planetary gearsets using several spur gear suns and
planets, which form a combination of a plus planetary gearset and a minus
planetary gearset.