Abstract: A reciprocating device for spray painting an object includes a plurality of mounting arms each having one end releasably retaining a spray painting device and an opposite end releasably coupled to one of a pair of spaced apart generally parallel vertically extending posts. The posts are attached to a driving mechanism which includes a servomotor coupled to one end of a crank arm having its other end rotatably coupled to a sliding block engaging a generally horizontally extending rod to convert the rotary motion of the motor to vertical motion of the rod. The rod is coupled to the ends of the posts and the motor is controlled as to its direction of rotation, speed of rotation and degree of rotation to define the excursion of the reciprocating movement and the speed of the movement. The assembly is mounted on rails for movement toward and away from the object to be painted by another driving mechanism.

Abstract: An improved wrist mechanism for a robot arm is disclosed. A first drive mechanism is provided which includes a hollow upper knuckle portion adapted for rotation about a first axis. The upper knuckle portion terminates in an angled end. A second drive mechanism is provided which includes a first hollow torque tube journalled in the upper knuckle portion for rotation relative thereto and a lower knuckle portion having an angled end journalled to the upper knuckle portion curved end for rotation about a second axis. The first torque tube and the lower knuckle portion engage each other for rotation together, and the first and second axes of rotation intersect at a first point. A third drive mechanism includes a second hollow torque tube journalled in the first torque tube for rotation relative thereto, an intermediate drive member journalled in the lower knuckle portion curved end, and an output tube journalled in the lower knuckle portion for rotation about a third axis.