A gearing assembly comprising: a differential configured to engage a first axle shaft and a second axle shaft of a vehicle (8, 9) and configured to be driven by a drive shaft of the vehicle; a differential control pinion gear configured to be driven by a variable speed reversible motor of the vehicle; a first plurality of adjustment gears configured to engage the differential and to engage the differential control pinion gear, the first plurality of adjustment gears comprising: a first planetary gear carrier; a first set of planetary gears (61a, 62a, 63a) coupled to the first planetary gear carrier; a second set of planetary gears (64a, 65a, 66a) coupled to the first planetary gear carrier; and a first externally toothed ring gear having external teeth configured to be driven by the differential control pinion gear and having internal teeth configured to intermesh with the first set of planetary gears; and a second plurality of adjustment gears configured to engage the differential and to engage the differential control pinion gear, the second plurality of adjustment gears comprising: a second planetary gear carrier; a third set of planetary gears (61b, 62b, 63b) coupled to the second planetary gear carrier; a fourth set of planetary gears (64b, 65b, 66b) coupled to the second planetary gear carrier; and a second externally toothed ring gear having external teeth configured to be driven by the differential control pinion gear and having internal teeth configured to intermesh with the third set of planetary gears; wherein the first plurality of adjustment gears and the second plurality of adjustment gears are configured to controllably alter a rotation rate of the first axle shaft relative to a rotation rate of the second axle shaft through rotation of the differential control pinion gear produced by the variable speed reversible motor. a differential configured to engage a first axle shaft and a second axle shaft of a vehicle (8, 9) and configured to be driven by a drive shaft of the vehicle; a differential control pinion gear configured to be driven by a variable speed reversible motor of the vehicle; a first plurality of adjustment gears configured to engage the differential and to engage the differential control pinion gear, the first plurality of adjustment gears comprising: a first planetary gear carrier; a first set of planetary gears (61a, 62a, 63a) coupled to the first planetary gear carrier; a second set of planetary gears (64a, 65a, 66a) coupled to the first planetary gear carrier; and a first externally toothed ring gear having external teeth configured to be driven by the differential control pinion gear and having internal teeth configured to intermesh with the first set of planetary gears; and a first planetary gear carrier; a first set of planetary gears (61a, 62a, 63a) coupled to the first planetary gear carrier; a second set of planetary gears (64a, 65a, 66a) coupled to the first planetary gear carrier; and a first externally toothed ring gear having external teeth configured to be driven by the differential control pinion gear and having internal teeth configured to intermesh with the first set of planetary gears; and a second plurality of adjustment gears configured to engage the differential and to engage the differential control pinion gear, the second plurality of adjustment gears comprising: a second planetary gear carrier; a third set of planetary gears (61b, 62b, 63b) coupled to the second planetary gear carrier; a fourth set of planetary gears (64b, 65b, 66b) coupled to the second planetary gear carrier; and a second externally toothed ring gear having external teeth configured to be driven by the differential control pinion gear and having internal teeth configured to intermesh with the third set of planetary gears; a second planetary gear carrier; a third set of planetary gears (61b, 62b, 63b) coupled to the second planetary gear carrier; a fourth set of planetary gears (64b, 65b, 66b) coupled to the second planetary gear carrier; and a second externally toothed ring gear having external teeth configured to be driven by the differential control pinion gear and having internal teeth configured to intermesh with the third set of planetary gears; wherein the first plurality of adjustment gears and the second plurality of adjustment gears are configured to controllably alter a rotation rate of the first axle shaft relative to a rotation rate of the second axle shaft through rotation of the differential control pinion gear produced by the variable speed reversible motor.