Abstract: An apparatus provides .theta.-rotational motion about a Z-axis. The apparatus is improved as follows. A stop structure is carried by the apparatus and rotates with it. The stop structure has a detent engagement structure. A detent structure comprises a rotatable member located adjacent to the stop structure. The rotatable member is mounted for free rotation about an axis parallel to the Z-axis. The rotatable member defines a plurality of detentes which are adapted for sequential engagement with the detent engaging structure as the stop structure rotates about the Z-axis. A biasing structure serves for biasing the stop member to deter it from rotating. The biasing structure is overcome by action of the detent engaging structure with any one of the detentes and otherwise prevents rotation of the stop member. A stationary detent is located adjacent the stop member. The stationary detent engages with and halts rotation of the stop member beyond a selected rotational position.

Abstract: A robotic arm mechanism provides motion to an end effector via a motor driving a drive pulley. The drive pulley is connected by a belt structure to drive a driven pulley. The motor is mounted to a bracket. The bracket is slidably mounted to a base plate. The bracket is positioned relative to the base plate to provide desired tension in the belt structure. The bracket is fastened to the base plate by a bolt structure which extend from the base plate orthogonally to the motor. A threaded bore extends fully through the bracket from a distal mouth thereof removed from the driven pulley. The bore has an axis which is located generally in a plane which is contiguous with or parallel to the axes of the respective drive and driven pulleys. The bore extends from an opening facing the distal side downwardly to the base plate and towards the axis of the driven pulley. A set screw is engaged with the bore and extends through it such that the screw's tip forcibly engages with the base plate.

Abstract: A vertical positioner comprises a rigid frame. A rigid vertically extending structure extends upwardly from a base to its upper end portion. A generally horizontal flange forms the structure upper end portion. It has a central opening and at least two peripheral openings. A vertically movable structure is telescopically mounted to the frame. It comprises an upper plate located above the flange. A lower generally parallel plate is located below the flange. A pair of parallel rods extend between the plates and pass through flange bearings. A central tube is connected between the lower and upper plates and passes through the flange via bearings. A motor is supported rigidly relative to the base for motivating relative vertical motion.