A hydraulic press is a mechanical machine used for lifting or compressing large items. The force is generated through the use of hydraulics to increase the power of a standard mechanical level. This type of machine is typically found in a manufacturing environment.
Invented in 1795 by Joseph Bramah, the hydraulic press is also known as the Bramah press. He used his knowledge of fluid mechanics and motion to develop this device. This invention significantly increased the compression power available, expanding the product groups and options available to other inventors. By applying hydraulics to a press, an entire class of machines was invented. There is a wide range of different hydraulic press machines, ranging from small table top units for hobbyists to huge machines used to create metal parts.
The primary concept used to provide power to the hydraulic press is that the level of pressure in a closed system is constant. This type of press has pistons with a fluid inside that is displaced by the pistons' inward movement. The fluid forces its way back into the space by moving the piston outward. The additional power is created through the movement of the fluid, which is confined to the system.
Pascal's law states that the pressure of a fluid within a closed system does not diminish, but instead acts with equal force on equal areas. In addition, this force will move at right angles to the walls of the container. It is important to ensure the hydraulic press is designed to withstand the pressure within the system and transfer that energy onto the press itself, and away from the structure.
When selecting a hydraulic press, it is important to realize that the amount of force generated is based on the size of the pistons, both in terms of piston head diameter and distance of movement. The amount of fluid moved by the piston is proportional to the ratio of piston head areas. This means a small piston would have to move a large distance to create enough force to displace the large piston any significant distance. To calculate the distance the large piston will move, divide the ratio of the piston head area by the distance the small piston is moved.
Remember that work is force multiplied by distance. As force increases on the larger piston, the distance the smaller piston travels must be decreased. This application of the core physics principle created the hydraulic press and resulted in significant developments in the manufacturing sector.