Pressure and Force:
The foundation of modern hydraulic powered systems were established when a scientist named Blaise Pascal discovered that pressure in a fluid acts equally in all directions. That concept is called as Pascal's Law. An application of Pascal's Law requires the understanding of the relationship between force and pressure.
Force might be defined as a push or pull exerted against the total area of a surface. That is expressed in pounds. Pressure is the amount of force on a unit area of the surface. That is, a pressure is the force acting upon one square inch of a surface. The relationship among pressure and force is expressed mathematically.
F = P x A
where:
F = force in lbf
P = pressure in lbf/in.2, (psi)
A = area in in.2
Example:
Within a hydraulic system, an oil pressure at the inlet to the cylinder is 1500 psi, and an area of the piston over that the oil pressure acts is two square inches.
Compute the force exerted on the piston.
Solution:
Because F = P x A, the force of the oil on the piston is calculated as follows.
F = 1500 lbf/in.2 x 2 in.2
= 3000 lbf