Abstract: A combined linear and circular drive mechanism for driving a spindle in an up or down direction and also in a circular path about an axis parallel to the spindle. The mechanism has a dual or compound nut which is driven to rotate in a fixed plane so as to drive a spindle threaded therethrough in an up or down direction. The dual nut mechanism has a pair of nut components having respective eccentrically positioned threaded openings, the openings being displaced from each other such that one of the nut components engages the threaded spindle to drive it in a first direction while it is being carried in a circle, and a second nut component engages the spindle to drive it in the reverse direction, also while the shaft is being rotated in a circle.