The hydrospanner was a type of common hand tool used as an all-purpose socket wrench and bit driver. It was used to tighten or loosen types of fasteners, such as nuts, bolts, and multiple sizes of screws and pins. Hydrospanners were in common use throughout the Galaxy. They were used in the building, repairing, and dismantling of any mechanical device or structure like droids, equipment, starships, and related works of engineering.
One more thing... I seached for pictures of hydrospanners, and only found a picture of "Pin The HyrdoSpanner on the Reverse power Coupling" And some lego stuff...
Anybody have on or can draw one please?
http://www.starwars.com/community/fun/caption/2005/02/captions20050201.html
All we have on how it works is this...from the same source Rex got his info...
A hydospanner worked by using a small yet powerful hydraulic compessor to turn a rotary driver which could be fitted with different types of standard bits. The driver was powerful enough to drive screws through duraplast and transparisteel. It could be powered either internally or externally.