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.