Which drive system is NOT typically used for rotary positioning?

The choice indicating "Mechanical only" is correct because it implies a singular focus on mechanical systems without considering how they typically operate in conjunction with other drive systems. In industrial settings, rotary positioning can be achieved through various drive systems, including pneumatic, electric, and hydraulic, all of which can effectively control rotational motion and positioning.

Mechanical systems alone, while they might provide some form of positioning through components like gears and linkages, generally do not encompass the full range of technologies commonly utilized for precision rotary positioning tasks. Typically, drive systems such as electric motors are favored for their speed, accuracy, and controllability, while pneumatic and hydraulic systems are often employed for applications requiring higher force and torque. Thus, the phrase "Mechanical only" implies a limitation that does not reflect the collaborative use of drive systems in modern industrial applications.