Machines that derive their Power from the Motion or Pressure of Water or some other liquid (see States Of Matter). Water or Oil under pressure is commonly used as a source of power for many types of
machines. The hydraulic press, used, e.g., to form three-dimensional objects from
sheet metal or plastics and to compress large objects, consists of two cylinders
of different size, each filled with liquid and fitted with a piston, and each
connected to a pipe (see Specifications - Piping) filled with the same liquid. According to Pascal's law, pressure exerted
upon the smaller piston is transmitted undiminished through the liquid to the
surface of the larger piston, which is Forced upward. A small pressure exerted on the smaller piston creates a stronger
force on the larger piston because the area (see Area - Circle, Area - Rectangle) of the latter is larger and the distance it moves is less. The same
principle is used to power the hydraulic jack, which is used to lift heavy loads. The
hydraulic elevator is also an application of Pascal's law.