The Actuator consists of a gearmotor, which drives the metric spindel through a spur gearing. Position is controlled with an incremental encoder. Typical repeatability is 3µm. The maximum allowable axial load is 1000N (cycled). More than 6000 of these actuators have been produced by BOEHM. Even under adverse environmental conditions, with temperature changes from –20°C to +20°C, no mechanical failure has occurred since 1985.
Up to 5 actuators are mounted under each reflector panel. A reflector consists of 176 panels. 848 actuators are mounted to each reflector. The actuators are remote controlled.