HTG_1_Physic_100305

Introduction to Hydraulics

By Jason Lim

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•So what is HYDRAULICS ?

•The word Hydraulics is derived from a Greek word “HYDOR”which means water.This comprised all things in affiliation with water.

•Today we understand under the term hydraulics the Transmission and control of force and movement by means of fluid.

•Fluid is therefore used to transmit energy .Mineral oil is used generally although a synthetic fluid,water or oil - water emulsion can be used .

Introduction


Hydraulics are also used in the following specified areas:

•Machine Tools•Presses•Plastic Machinery•Heavy Machinery•Civil Eng•Shipbuilding•Construction Machines•Mining•Agricultural Eng•Food , Drinks Tobacco and Packaging Industries•and many others etc......

Introduction…cont…


The field of Hydro Mechanics is broken down as follows:-

•Hydrostatic - Mechanic of still fluid A good example is the transfer of force in Hydraulics.

•Hydrodynamic - mechanics of moving fluid. A good example is the conversion of flow energy in turbines in a hydro electric plant.

Introduction….cont..


So by knowing that Hydraulics means transmission of energy, What other type of power transmission are there ?

Introduction….cont..


Hydraulic TANK or RESERVOIR

Filler / Breather

Integral Oil Cooler

Radial Piston Pump

Suction StrainerReturn Line Filter

Check Valve

Motor

Air Bleeding PlugHand control Valve

Pressure Relief Valve

Soleniod Unloading Valve

60 L AluminiumTank

RRcs - 1B Constant PressureAutomatic Cone Control System Hydraulic Power Pack


Physic Terms

1 ) Mass- A weight force is created by a mass on the ground due to gravity- Symbol : m

2 ) Force - According to Newton’s Law :

Force = mass x acceleration- If the general acceleration a is replaced by the acceleration due to due to gravity g ( g = 9.81 m/s2 ) , the following is obtained :Weight force = mass x acceleration due to gravity

F = m x g For a mass 1kg, this results in a weight force of F = 1kg x 9.81 m/s2 = 9.81kgm/s2

- The SI unit for force is the Newton1N = (kg m)/ s2

A mass of 1kg creates a force of 9.81N on the ground


FORCE :1daN = 10N1kN = 100daN1000daN = 1 t

Physic Terms…cont….


3 ) Pressure

- In description of processes involving fluids, pressure is one of the most important quantities.

- If a force acts perpendicularly to a surface and acts on the whole surface, then the force F divided by the area of the surface A is the pressure P

P = _F_

A- The derived SI unit for pressure is the Pascal:

1N / m2 = 1 Pascal ( 1 Pa )

- In practice, it is more common to use the bar unit

1 bar = 105 Pa



Pressure applied to a confined static fluid acts equally and undeminished in all directions, with equal force on equal areas at right angle to all contacting surface.

P

F

A



PRESSURE ACTS EQUALLY IN ALL DIRECTIONS

Pressure reaction in liquid


PRESSURE DUE TO EXTERNAL FORCEPASCAL

F

P

A

F :- FORCE IN NEWTONS

A :- AREA IN CM SQUARE

P :- PRESSURE IN Bar

Pressure reaction due to external force…cont…


FLUID PRESSURE IN AN IRREGULAR CONTAINER

Pressure reaction due to external force …cont…


AREA : 1m = 10000cm,1mm = 10 cm = 0.01 cm

2

22

2 2 - 2



P = FA

EXAMPLE: Given that A1 = 10cm = 0.001m

F = 10000 N

2 210

10000

= 0.001m2

Area which is in cm to be converted into m

Culculate the pressure required?

@#+*&$ %$#@!)(&*

Calculation


10000N

0.001m

=10000000 N = 100.10 Pa m = 100 bar

2

2

5

Therefore : 1 Bar = 100000 Pa10000000 N

m = 10000000 N100000 Pa

= 100 Bar

2

FA

p =

Calculation…cont…


Example 2

Given that :-

P = 100.10 Pa

A2 = 1cm = 0.0001m

5

Culculate the Force required?

22

F = p. A

= 100.10 Pa . 0.0001m

= 1000

F = 1000 N

N . m m

2

2

2

5

Calculation…cont…


FORCE TRANSMISSION

Requirement for equilibrium :

F1F2

A1 A2

F1p1 =

A1

F2p2 =

A2

p1 p2

Force transmission


FORCE TRANSMISSION

F1F2

A1 A2p1 p2

p1 = p2

The following equation applies when the system is in equilibrium

Force transmission….cont..


FORCE TRANSMISSION

F1F2

A1 A2p1 p2

p1 = p2

The following equation applies when the system is in equilibrium

Force transmission….cont..


Simple Hydraulic Circuit


Hydraulic Circuit

DIRECTIONAL CONTROL VALVE

FLOW CONTROL VALVE

CYLINDER

PUMP MOTOR

RETURN LINE FILTER

PRESSURE RELIEF VALVE

TANK / RESERVOIR

Hydraulic Circuit


Hydraulic Circuit….cont..





1 ) Hydraulic Pump,

2 ) Hydraulic Tank

3 ) Check valve

4 ) Pressure Relief Valve

5 ) Cylinder

6 ) Directional Control Valve

7 ) Flow Control Valve

Documents

HTG_1_Physic_100305