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Sunday, 11 January 2015

APPLICATION OF FLUID POWER : HYDRAULIC JACK


This post is basically based on the information about hydraulic power applications 

Why we should read this post???

We must understand that what we are going to secure after reading this post as we are consuming our valuable time so we must have to secure some precious information's. 

Purpose of this post is as mentioned following

  1. Provide the practical knowledge about the fluid power, hydraulic jack and application areas of Bernoulli’s principle.
  2. Determination of mechanical advantage
  3. Determination of plunger and ram movement
  4. Effect of varying force and areas over the pressure in hydraulic jack
  5. In this post we will also consider the equipment and variables those are used for hydraulic lab based on fluid power 
So let us come to point 

Concepts that we must understand......

Bernoulli’s Principle

According to Bernoulli’s principle, fall or rise in pressure of flowing fluid will always be accompanied by the increase or decrease in speed. Vice versa we can also say that decrease or increase in speed of flowing fluid will cause the increase or decrease in fluid pressure.

Bernoulli’s principle could be considered as principle of conservation of energy.


Bernoulli’s Principle is very important principle that involves the movement of fluid due to the difference in pressure.

Let us think that fluid is moving in a direction which is horizontal and accounts a difference in pressure, this difference in pressure will provide a net force and this net force will provide an acceleration of the fluid according to Newton’s second law. 


Let us consider the fundamental relation

Change in kinetic energy = work done
Change in kinetic energy = - pressure change * Area* Distance
Change in (kinetic energy /volume) + Change in pressure = 0
Pressure + kinetic energy /volume = constant
 
Let us consider some applications of Bernoulli’s principle

Pascal law

According to Pascal law, any increase in pressure in incompressible fluid will be transmitted equally in all the directions.

Let us consider some parameters as mentioned below
W= weight, that we have to lift
F= Force, which is applied over the plunger
A= Ram area
a= plunger area
Pressure applied over plunger, P = F/a

According to Pascal law, pressure at Ram will be equal to Pressure applied over plunger
Pressure at Ram= P = W/A
W/A= P / a
 
Let us consider some application of Pascal’s law and fluid power

Let us think what equipment ,we will require if we go for experiment for understanding hydraulic power 
  1. Bottle Jack with Gauge 30 cm Ruler
  2. Pressure Stage S-Hook
  3. Vernier Caliper 0-12 kg Spring Scale
We will also have to think the variables and these variables will be considered Area and force . Pressure depends on area and force. 

Application

The mechanism of spinning ball utilized in sport might be understood with the help of Bernoulli’s Principle. If we consider some sports such as cricket, baseball, table tennis or soccer, sport men used to spin the ball in order to make it like curve in specified direction. When ball will spin and air will come in contact with the spinning ball, there will be two considerations.
  1. Air also moving in same direction in which ball is spinning, in this case spin will be sped up
  2. Air is moving in opposite direction in which ball is spinning, in that case spin will be slowed down
Hence, pressure of air will be higher on one side as compared to opposite side and higher pressure of air will try to compensate the lower pressure of air and try to push the ball-resulting in that curve.

Hydraulic Jack

Hydraulic jack is commonly used in work shop or in maintenance applications, for example if we go for maintenance of E.O.T crane wheel replacement. We need hydraulic jack in order to lift the End carriage for removing and re-installation of crane wheel.

The hydraulic jack is basically a mechanical device which is applied in order to lift the heavier loads with the application of very small force.

Hydraulic jack work on the principle of Pascal’s law, according to which increase in pressure in incompressible fluid will be transmitted equally in all the directions.

Let us consider the part or components of hydraulic jack as mentioned below.

Working principle

Let us consider working principle of hydraulic jack with above figure. Let us consider plunger and ram and both are operating inside cylinder of different diameter and connected with each other with the help of a chamber filled with working fluid.

Let us consider some parameters as mentioned below
W= weight, that we have to lift
F= Force, which is applied over the plunger
A= Ram area
a= plunger area
Pressure applied over plunger, P = F/a

According to Pascal law, pressure at Ram will be equal to Pressure applied over plunger
Pressure at Ram= P = W/A
W/A= P / a
W= F x A/a

We can see in above mentioned equation that after applying a smaller force F, will be able to lift the heavier weight W. Because, A will be greater as compared to a


So we may say after reading this post that 
  1. After applying smaller force, we can lift much heavier load due to mechanical advantage of hydraulic jack.
  2. We have understood that all hydraulic system works on the law of Pascal’s law.

Also discuss

Effect of corrosion
Shaft alignment procedure
Application of hydraulic accumulator

Do you have any suggestion? Please write in comment box

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