Servo-Automatas are a special type of robots used by the Adeptus Mechanicus. These things are a type of logistical and repair robots used by the Imperium. Unlike Servitors, these servants are mechanical rather than biological in origin. Additionally, they aren't part of the Legio Cybernetica due to the fact that by function, they are not considered military assault robots (Although the Skylax is considered an armed variant of the Servo-Automata and looks uncannily similar in appearance).
Because they are logistical by nature, it can be assumed that they are related to the Servo-skulls used throughout the Imperium. They are equipped with Servo-arms which can be a good improvised weapon and frequently accompany Enginseers in groups of four.
On the tabletop, the Servo-Automata is a surprisingly tough unit especially for a non-front line infantry and won't be found wanting in other areas given the right equipment. You may take up to 8 of these with a single unit. Normally they are only equipped with close-combat weapons, but you will most likely give them a Las-lock as its only 1 point a piece.