Head engineer of Steel City, Jules is the one to work with all of the machines to make sure they're properly maintained and functioning well. She's highly skilled in this, as well as any electrical work that needs to be done. She teaches engineering to her students, though she tries to prevent them from learning the engineering required to run the city, for fear of one of them pulling a nasty prank and messing up the city's machines.

Eve was Jules' top student and very knowledgeable about machines and their inner workings, and is able to replace and fix parts of technology that's been the pride of Steel City for centuries. (Jules knows the most about that, but Eve took to it quickly).

A former construction worker, Wind learned from Eve on the side, as he was not allowed to take part in official lessons on the specialized machinery of Steel City. Eve taught him what she knew, anyway, at great personal risk. He helps her maintain a very peculiar piece of machinery in the city.