Oscillating and continuous motion gear drive assembly

A vehicle wheel steering system comprising:

• a steering motor having an output shaft which is capable of continuous rotation through only a predetermined steering angle;
• a driven gear fixedly secured to and rotatable with said output shaft;
• a drive gear having a first segment including gear teeth extending around a first predetermined arcuate length of the drive gear perimeter and a second segment without gear teeth on its perimeter adjacent the first segment;
• a backdrive gear coaxially mounted to rotate in unison with said drive gear, said backdrive gear having a first segment including gear teeth extending about a second predetermined arcuate length of the backdrive gear perimeter, and a second segment without gear teeth on its perimeter adjacent the first backdrive gear segment;
• first and second intermediate backdrive gears coaxially mounted to rotate in unison, said first intermediate backdrive gear being in constant mesh with said driven gear and said second intermediate backdrive gear being arranged to mesh with the first segment of said backdrive gear;
• a steerable wheel secured to rotate in unison with said drive gear, said vehicle wheel steering system enabling steering of said steerable wheel through said motor, said driven gear and said drive gear through said predetermined steering angle, said vehicle wheel steering system being also arranged such that continuous rotation of said drive gear through 360.degree. results in oscillation of said driven gear, with the gear teeth of the first segment of said drive gear directly meshing with the gear teeth of said driven gear to directly drive said driven gear when the drive gear is rotated in one direction over an arcuate length corresponding with said first predetermined arcuate length of said first segment of said drive gear and, on continued rotation of said drive gear in said one direction, to drive said driven gear in an opposite direction through the gear teeth of the first segment of said backdrive gear directly meshing with the gear teeth of said second intermediate backdrive gear to produce said opposite rotation.