1. I – Basics of Hydraulics
Unit I
I – Basics of Hydraulics

2. Function Vs Properties of Hydraulic Fluids
Introduction
Function Vs Properties of Hydraulic Fluids
Function
Property
Medium for power transfer and control
Low compressibility (high bulk modulus)
Fast air release
Low foaming tendency
Low volatility
Medium for heat transfer
Good thermal capacity and conductivity
Sealing Medium
Adequate viscosity and viscosity index
Shear stability
Lubricant
Viscosity for film maintenance
Low temperature fluidity
Thermal and oxidative stability
Hydrolytic stability / water tolerance
Cleanliness and filterability
De-miscibility
Anti-wear characteristics
Corrosion control

3. Function
Property
Pump efficiency
Proper viscosity to minimize internal leakage
High viscosity index
Special function
Fire resistance
Friction modifications
Radiation resistance
Environmental impact
Low toxicity when new or decomposed
Biodegradability
Functioning life
Material compatibility

4. Functions of the Fluid The Hydraulic Fluid has four primary functions
To transmit power
To lubricate moving parts
To seal clearances between parts and
To cool or dissipate heat

5. GENERAL TYPES OF FLUIDS
Classified based Properties of fluid:
Ideal Fluid: A fluid which is incompressible and is having no viscosity is known as an ideal fluid. Ideal fluid is only an imaginary fluid as all the fluids, which exist, have some viscosity.
Real Fluid: A fluid which possesses viscosity is known as real fluid. All fluids, in actual practice are real fluids.
Newtonian Fluid: A real fluid in which the shear stress is directly proportional to the rate of shear strain is known as a Newtonian fluid.
Non-Newtonian Fluid: A real fluid in which the shear stress is not proportional to the rate of shear strain  known as a Non-Newtonian fluid.
Ideal Plastic Fluid: a fluid in which shear stress is more than the yield value and shear stress is proportional to the rate of shear strain is known as ideal plastic fluid.

6. Fluids applied today Petroleum Rapeseed oil, or canola oil
Water-glycol
Poly-glycol
Oil-in-water
Water
Water-in-oil
Synthetic fire-resistant fluids
Vegetable oils

7. Types of Fluid Power System
Based on Control system
Open-loop
Closed loop
Based on Type of Control
Fluid logic Control
Electrical Control
Electronic Control
Based on Fluid
Hydraulic
Pneumatic

8. Fluid Power Symbols

12. Questions What are the primary functions of hydraulic fluid?
Name few properties of a hydraulic fluid
Mention Characterizes liquid and gas.
What is density of fluid?
What is meant by viscosity?
What is the significant of viscosity, with reference to selection of fluids?
What are the undesirable effects when oil having high viscosity?
What are the undesirable effects when oil having very low viscosity?
State the effects of temperature and pressure on viscosity of fluid.
Define viscosity index
What is meant by compressibility of fluid?

13. Function
Properties
Classifications
Functions Vs Properties
Hydraulic Fluid

14. Summary Primary functions It is a substance, capable of flowing.
To transmit power
To lubricate moving parts
To seal clearances between parts and
To cool or dissipate heat
It is a substance, capable of flowing.
Classified into liquid, gas vapor
Liquids are assumed to be incompressible
Gases are compressible
Classified based Properties of fluid:
Ideal fluid
Real fluid
Newtonian fluid
Non-Newtonian fluid
Ideal Plastic Fluid

15. MCQ
  are shapeless substances that take the shape of their containers; they can be liquids or gasses.
a) Air b) Water c) Oil d) Fluids
power is pressurized liquid or gas in a closed system.
a) Fluid b) Electrical c) Mechanical d) Thermal
3. _____________________use pressurized oil or other liquids.
a)Pneumatics b) hydraulics c) Electrical d) Electromechanical
use pressurized air or other gasses.
 Pneumatics b) hydraulics c) Electrical d) Electromechanical
5. By itself, fluid has no power, but when confined and placed under , fluid can transmit power that can be stored, directed and made to do work.
a) Volume b) Force c) pressure d) Area