Fluid power systems-overview

Dr.D.R.S.Raghuraman

History of fluid power systems

First hydraulic pump :

Double pump delivering a fluid flow rate of 10 lpm;

Piping network :100,000 km( 2.5 times around the earth)

Continuous operation: almost maintenance free

Can you guess which is that pump?

History

Human blood circulatory system

Age 50: Hearts of 10 men should have

pumped a volume of blood equal to that of

the Great Egyptian Pyramid( how much?)

Evolution of fluid power( Oil hydraulics first

and then pneumatics)

Blaise Pascal-1647” Law of hydrostatics”

Bernoulli’s book-Hydrodynamics=>kinetic theory of gases,jet propulsion,law of conservation of energy-1738

Mid 19th century,fluid power important in industrial and civil sectors eg: England,many cities had central hydraulic distribution systems with pumps driven by

……….?

History…

London Hydraulic Power company used fluid

power ( hydraulics) for dock cranes and

bridges to lifts in private house holds in

Kensington and Mayfair

1930s -12m3 / min average hydraulic flow

was used to lower or lift anything.Water

was pumped beneath the streets of

London for the above.

History…

Benjamin’s Franklin discovery of electricity

changed everything.More and more

electric power was used for material

handling.

1925 Harry Vickers developed a vane type

pump.Thence onwards hydraulic power

became to be used in industry till today.

Power

Mechanical Power

Power

Power….

Power

Fork lift

Mechanical Parameters

Advantages of oil hydraulics

High power-weight ratio( minus power pack)

Self lubrication

No saturation phenomenon

High force to mass and torque to inertia ratios,

high stiffness,high acceleration,high response

high stiffness of cylinders,protection against

overloading simple,high energy

storage,transmission flexibility(better than

mechanical elements)

Precise motion and control but slow

DISadvantages..con

Hydraulic power not readily avaialble,High

costs,high inertia of transmission

lines,temperature limits,fire hazard(

mineral oils),Oil filtration .

Basic hydraulic circuit

Advantages of

pneumatic/vacuum systems Compressible like springs

Fast response time

Use atmospheric air or gas

Short displacements

Easy to transport

Safe at low pressures

Storage

DISadvantages of pneumatic

systems • Installation of pneumatic systems such as

compressors, air filter, lube tube, dryer,

regulators, etc.

• Leakages cause energy loss

• Noisy on the exhaust side so mufflers

needed

• Water vapor in the air condenses

• Dry air needs an oi mist for lubrication

Commonly asked questions

What is a fluid power system?

Describe the function of fluid power systems.

State the advantages/disadvantages of hydraulic

and pneumatic power systems.

What are the symbols used in fluid power systems

and why are they used?

What are the different application of fluid power

systems?

What are the manpower requirements of a fluid

power industry?

CAQuestions?

What is an electrohydraulic system?

What are the components of an oil hydraulic

system?

What are the components of a pneumatic system?

What is an open circuit system?

What is a closed loop system?

What type of sensors and control systems can be

used in electrohydraulics?

Compare the different type of systems existing in

industry.

Can we have a vacuum based system and for

what application?

CAQuestions?

Who are the major manufacturers of

hydraulic systems in India and abroad?

Who are the major manufacturers of

pneumatic systems in India and abroad?

Visit any oil hydraulic and pneumatic

industry and list out the various components,

their symbols ,their uses, maintenance and

troubleshooting aspects.