HYDRAULIC SYSTEMS

by Mohanraj M.E

Erode

Fluid Power System• The pressure fluids to move one place to another. – Hydraulic System (Hydour-Water in Greek word )

(High accuracy)Examples: Space, defense, machine tool applications, agriculture and automobiles.

– Pneumatic System (Pneuma- Air in Greek word)(Less accuracy)Examples: pneumatic hammers, drills, hoists, cranes.

1. Fluid power system and 2. Hydraulic System3. Oil Hydraulic System

SERVICE PRPERTIES OF HYDRAULIC FLUIDS

1)Viscosity

-To affect the running fluid

Depends on,-Temperature -Thickness- Pressure

Density = Viscosity Temperature +++Viscosity ---

Pressure +++Viscosity ---

So we chose fluid is to reduced the above failures

2) Viscosity Index

-Temperature Changes to Change the Viscosity

-Integer (0 to 100)

To choose the High viscosity index fluid.

3) Oxidation stability

Chemical Oil + AIR(OXYGEN) Oxidation

Reaction

Oxidation Inhibitors Or Additives …Ex: Silicon Polymers, Nitrogen Components etc.

4) De-emulsibility

-Reduce the Forming in hydraulic fluid -Separate the forming and

hydraulic fluid

5) Lubricity

-Lubricate the all engine parts during function of system.

-avoid friction loss by using high lubricity having fluid will choose,

6) Rust Prevention -Rust is an iron oxide, usually red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture

Ex: Sprayer Paints etc.

7) Toxicity

-Poison character or Silly Character. - This behaviour defiantly affect the human being..

8) Cloud point

-Cloud point refers to the temperature below which wax in oil .

9) Flash and Fire Point

At the flash point, the vapor may cease to burn when the ignition source is removed. The flash point is not to be confused with the auto ignition temperature (which does not require an ignition source) or with the fire point (the temperature at which the vapor continues to burn after being ignited).

 HYDRAULIC ACCUMULATORA hydraulic accumulator is a pressure storage reservoir in

which a non-compressible hydraulic fluid is held under pressure by an external source. The external source can be a spring, a raised weight, or a compressed gas.

Usage of Accumulator

1. Leakage compensation2. Shock absorber3. Secondary power sources4. Emergency power sources5. Thermal expansion compensator 6. Temporary storage receiver etc.

Leakage compensation

SHOCK ABSORBER A shock absorber (in reality, a shock "damper") is a mechanical or 

hydraulic device designed to absorb and damp shock impulses.

SECONDARY POWER SOURCE Supply to extra fluid to hydraulic system.

EMERGENCY SOURCEDuring Emergency time to supply hydraulic

fluid from accumulator. If any fault in pump.

THERMAL EXPANSION

Types of accumulator

1)Weight loaded accumulator

2)Spring loaded accumulator

3)Gas loaded accumulator

Gas Loaded Accumulators

Symbols of Accumulator

PRESSURE INTENSIFIER

Pascal's law - pressure applied anywhere to a body of fluid causes a force to be transmitted equally in all directions; the force acts at right angles to any surface in contact with the fluid; "the hydraulic press is an application of Pascal's law" Pascal's law of fluid pressures.

PASCAL'S LAW

A hydraulic intensifier is a device which is used to increase the intensity of pressure of any hydraulic fluid or water, with the help of the hydraulic energy available from a huge quantity of water or hydraulic fluid at a low pressure.

These devices are very important in the case of hydraulic machines, mainly hydraulic presses, which require water or hydraulic fluid at very high pressure which cannot be obtained from the main supply directly.

There are three main parts in the hydraulic intensifiers to be noted. They are1. Fixed ram,2. Hollow inverted sliding cylinder,3. Fixed inverted cylinder.

Application :Moulding Machine, Riveting machine, Spot Welding Machine and Hydraulic Presses.

Fluid Power PumpsPump:

-Important system in hydraulic system -Motor helps to convert electrical energy into mechanical energy-Pump helps to convert mechanical energy into fluid flow energy.

Classification of pumps: 1. Gear pump External Gear Pump2. Vane pump3. Radial pump Internal Gear Pump

External Gear Pump:4. Mostly Used in hydraulic system. 5. Equal two meshing gear fixed inside of casing. Merits: 1)Simple in construction 2) Comfortable for all area 3)High pressure (Apporx. 150bar) 4) Low cost.

Internal Gear Pump:Here Spur and internal gear meshing with help of crescent seal and

casingMerits:

1)Simple in construction 2) Comfortable for all area 3) Low cost. Demerits:

1) Less pressure (70bar) 2) Less Capacity

Vane Pump:Here Casing, Shaft, rotor and eccentricity.

Merits: Oil Leakage less and High Volumetric efficiency 95% and medium cost.

Demerits: 1) Less pressure 2) Less Capacity

Radial Gear Pump1. Fixed pintle, cylinder block and reaction ring.

Merits: 1) Smooth Operation 2) Pump Output high3) high volumetric efficiency (98%) 4) High Pressure (Above 500bar)

Demerits :1) Difficult Construction and High cost.

Thank u