Below is a list of Hydraulic Press manufacturers from Chicago, Illinois. A hydraulic press is a press machine that uses hydraulic pressure, or fluid pressure, in order to exert force on an object. Also known as Bramah presses, after their inventor Joseph Bramah, hydrolic presses depend on Pascal's principle; mainly, that the pressure throughout a closed system will act with equal force on all areas. As both the most common and most efficient type of industrial press, hydraulic presses apply a large lifting or compressing force that cannot be achieved using pneumatic presses or mechanical presses.