Hydrospanner/Legends
The hydrospanner was a type of common hand tool used as an all-purpose socket wrench and bit driver.
Operational use

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.
Most common hydrospanners could create a large amount of torque with little effort on the user's part, and offered various features for convenience. The Regallis Engineering FastTurn-3 Hydrospanner had an internal power source with a tension adjuster and a hinge on the socket driver to allow the user to access bolts and such in tight angles. The FastTurn-3 also had a spare bit compartment in the handle and a data port to connect a diagnostic device or datapad. The FastTurn-3 could also fit different sized nuts ranging from 2mm to 250mm in diameter, while using a small fusioncutter to remove molecular adhesives or welds before loosening.
How it worked

A hydrospanner worked by using a small yet powerful hydraulic compressor 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.
Behind the scenes
The hydrospanner is akin to real world power drills and socket wrenches. It is frequently mentioned in the Expanded Universe, though its purpose and operation is rarely explained. Also, a common expression equivalent to the real world expression 'throw a spanner in the works' was "throw a hydrospanner in the works."