The Green Bank Telescope's (GBT) design requirements have led to the implementation of an instrument with an active primary reflector. The design of the active primary reflector or active surface has presented many challenges. The active surface system consists of 2209 electro-mechanical actuators and associated control electronics. Since the actuators are mounted on a tipping structure, it was required that they support a significant side-load. Such devices were not readily available commercially so they had to be developed. Additionally, actuator requirements included low backlash, repeatable positioning, and an operational life of at least 20 years.