Pascal’s Principle

Pascal’s principle states that when pressure is applied to an enclosed fluid, the pressure will be transmitted equally throughout the whole enclosed fluid.


Pascal’s Principle in Mathematical Expression 

Input pressure = output pressure
P₁ = P₂
 since
Pressure , P = Force , F / Area , A

therefore
 F₂ / A₁  = F₂  / A₂


Explain hydraulic system

•  A small input force, F₂ is applied to the small piston resulting in a large output force, F₂.  

•  Based on the Pascal’s Principle, the pressure is transmitted uniformly in all directions,


•  When incompressible fluid is moved through a hydraulic system, the volume through which the input system
moved must be the same as the volume through which the output system,
 Hence   A₁ d₁   =  A₂d₂

•  Hydraulic systems acts as a force multiplier.  They multiply the input force by a certain factor to gain a larger output force.

•  The magnitude of the force at the large piston depends on
(a) the force, F₂, applied to the small piston,

Magnitude of the force = F₂ / F₁

(b)  the ratio of the surface area of the piston,

Magnitude of the force = A₂ / A₁

•  A hydraulic system must not contain any air bubbles in any position of its hydraulic fluid system.  This will reduce the efficiency of the system as part of the applied force will be used up to compress the air bubbles.