A power train for a vehicle includes a gearbox with an input shaft and an
output shaft and is configured such that the input shaft drives the
output shaft at a single speed ratio in a first direction and a single
speed ratio in a second direction. The output shaft is coupleable with
the front and rear vehicle axles to separately drive each axle. Further,
a continuously variable transmission is connected with an engine shaft
and with the gearbox input shaft such that the engine shaft drives the
input shaft within a range of speed ratios from less than 1 to greater
than 3. Front and rear differentials are coupled with each axle and with
the output shaft and drive the axles at different speed ratios such that
a base surface drives the front axle independently of the front
differential when at least one rear wheel rolls upon the surface.