Abstract: Improved steering systems are provided for skid-steering vehicles such as military tanks, track-type tractors and the like. A diesel engine may be used to rotate a drive shaft interconnected by port and starboard planetary gear assemblies, to apply driving power simultaneously to both track-drive mechanisms. Steering is provided by port and starboard hydraulically-actuated motors, each positively interconnected with the ring gear or other suitable component of its respective planetary gear assembly, whereby each track-drive mechanism may be controlled separately and independently of the other.