text: Ummm what exactly are you asking, ANY hydraulic device uses fluids. The prefix "Hydro" (or Hydr before a vowel) means water or fluid. What particular properties are you asking about?\n\nis this a school project or for a science fair? check google, but basically they all work on a cylinder. for example a log splitter.\nhttp://science.howstuffworks.com/hydraulic2.htm