Abstract: A theta robot with integrated preload system in one embodiment includes a cable-operated drive mechanism including a rotatable pulley drum, motor drive operably coupled to the drum by drive cable, and follower piston cylinder operably coupled to the drum by a follower cable. The piston cylinder may be under vacuum and operably applies a tensile load and resistance on the pulley drum via the follower cable which eliminates clearance between meshed driving and driven components of the drive mechanism. When the motor drive feeds out drive cable, the pulley drum rotates in a first rotational direction, and when the motor drive retracts drive cable, the pulley drum rotates in an opposite second rotational direction. The vacuum piston cylinder operates to keep the drive cable in a taut condition when the motor drive feeds out the drive cable. The theta robot has broad applicability to numerous workpiece fabrication processes including semiconductors.