Abstract: A dual drive mechanism for medical/dental chair comprising a single motor drive and a pair of linearly driven shafts. In one embodiment, the dual drive mechanism provides a self-locking, reliable and easily maintainable system for vertically displacing one portion of a medical/dental chair relative to another portion of the medical/dental chair. In other embodiments, the dual drive mechanism drives both shafts in a single direction to increase drive power, engages each shaft to a common part and drives both shafts in opposite directions to tilt or rock the common part and employs shafts having different drive ratios to drive separate parts at separate rates.

Abstract: A chuck assembly which is adapted for quick and easy engagement and disengagement with work arbors having various working tools mounted thereon. The chuck assembly comprises an elongate cylindrical chuck member having a longitudinal bore extending therethrough. One end of the chuck member is adapted to be attached to the shaft of a drive motor and the other end is adapted to receive a work arbor in concentric engagement therewith. Means are provided in combination with the chuck member for positively locking the work arbor in engagement with the chuck member when the chuck member and arbor are in rotational movement about their longitudinal axes. When the chuck assembly is at rest, the arbor is easily and quickly disengaged from the chuck member by moving the locking means to its disengaging position and pulling the arbor from the end of the chuck member.