Three axis pneumatic modern trailer

CHAPTER-1

1. INTRODUCTION

Automation can be achieved through computers, hydraulics, hydraulics, robotics,

etc., of these sources, hydraulics form an attractive medium. Automation plays an

important role in automobile. Nowadays almost all the automobile vehicle is being

atomized in order to product the human being. The automobile vehicle is being atomized

for the following reasons:

To achieve high safety

To reduce man power

To increase the efficiency of the vehicle

To reduce the work load

To reduce the fatigue of workers

To high responsibility

Less Maintenance cost

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CHAPTER-2

2. LITERATURE SURVEY

2.1 PNEUMATICS:

The word ‘pneuma’ comes from Greek and means breather wind. The word

pneumatics is the study of air movement and its phenomena is derived from the word

pneuma. Today pneumatics is mainly understood to means the application of air as a

working medium in industry especially the driving and controlling of machines and

equipment.

Pneumatics has for some considerable time between used for carrying out the

simplest mechanical tasks in more recent times has played a more important role in the

development of pneumatic technology for automation.

Pneumatic systems operate on a supply of compressed air which must be made

available in sufficient quantity and at a pressure to suit the capacity of the system. When

the pneumatic system is being adopted for the first time, however it wills indeed the

necessary to deal with the question of compressed air supply.

The key part of any facility for supply of compressed air is by means using

reciprocating compressor. A compressor is a machine that takes in air, gas at a certain

pressure and delivered the air at a high pressure.

Compressor capacity is the actual quantity of air compressed and delivered and the

volume expressed is that of the air at intake conditions namely at atmosphere pressure

and normal ambient temperature.

The compressibility of the air was first investigated by Robert Boyle in 1962 and

that found that the product of pressure and volume of a particular quantity of gas.

The usual written as

PV = C (or) PıVı = P2V2

2

In this equation the pressure is the absolute pressured which for free is about 14.7

Psi and is of courage capable of maintaining a column of mercury, nearly 30 inches high

in an ordinary barometer. Any gas can be used in pneumatic system but air is the mostly

used system now a days.

2.2 SELECTION OF PNEUMATICS:

Mechanization is broadly defined as the replacement of manual effort by

mechanical power. Pneumatic is an attractive medium for low cost mechanization

particularly for sequential (or) repetitive operations. Many factories and plants already

have a compressed air system, which is capable of providing the power (or) energy

requirements and the control system (although equally pneumatic control systems may be

economic and can be advantageously applied to other forms of power).

The main advantage of an all pneumatic system are usually economic and

simplicity the latter reducing maintenance to a low level. It can also have out standing

advantages in terms of safety.

2.3 PRODUCTION OF COMPRESSED AIR:

Pneumatic systems operate on a supply of compressed air, which must be made

available. In sufficient quantity and at a pressure to suit the capacity of the system. When

pneumatic system is being adopted for the first time, however it wills indeed the

necessary to deal with the question of compressed air supply.

The key part of any facility for supply of compressed air is by means using

reciprocating compressor. A compressor is a machine that takes in air, gas at a certain

pressure and delivered the air at a high pressure.

Compressor capacity is the actual quantity of air compressed and delivered and the

volume expressed is that of the air at intake conditions namely at atmosphere pressure

and normal ambient temperature. Clean condition of the suction air is one of the factors,

which decides the life of a compressor. Warm and moist suction air will result in

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increased precipitation of condense from the compressed air. Compressor may be

classified in two general types:

1. Positive displacement compressor.

2. Turbo compressor

Positive displacement compressors are most frequently employed for

compressed air plant and have proved highly successful and supply air for pneumatic

control application.

The types of positive compressor

1. Reciprocating type compressor

2. Rotary type compressor

Turbo compressors are employed where large capacity of air required at low

discharge pressures. They cannot attain pressure necessary for pneumatic control

application unless built in multistage designs and are seldom encountered in pneumatic

service.

2.4 RECIPROCATING COMPRESSORS:

Built for either stationary (or) portable service the reciprocating compressor is by

far the most common type. Reciprocating compressors lap be had is sizes from the

smallest capacities to deliver more than 500 m³/min. In single stage compressor, the air

pressure may be of 6 bar machines discharge of pressure is up to 15 bars. Discharge

pressure in the range of 250 bars can be obtained with high pressure reciprocating

compressors that of three & four stages.

Single stage and 1200 stage models are particularly suitable for pneumatic

applications , with preference going to the two stage design as soon as the discharge

pressure exceeds 6 bar , because it in capable of matching the performance of single stage

machine at lower costs per driving powers in the range .

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CHAPTER-3

3. FACTORS DETERMINING THE CHOICE OF MATERIALS

The various factors which determine the choice of material are discussed below.

3.1 Properties:

The material selected must posses the necessary properties for the proposed

application. The various requirements to be satisfied can be weight, surface finish,

rigidity, ability to withstand environmental attack from chemicals, service life, reliability

etc.

The following four types of principle properties of materials decisively affect their

selection

a. Physical

b. Mechanical

c. From manufacturing point of view

d. Chemical

The various physical properties concerned are melting point, Thermal

Conductivity, Specific heat, coefficient of thermal expansion, specific gravity, electrical

Conductivity, Magnetic purposes etc.

The various Mechanical properties Concerned are strength in tensile, compressive

shear, bending, torsional and buckling load, fatigue resistance, impact resistance, elastic

limit, endurance limit, and modulus of elasticity, hardness, wear resistance and sliding

properties.

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3.2 Manufacturing Case:

Sometimes the demand for lowest possible manufacturing cost or surface qualities

obtainable by the application of suitable coating substances may demand the use of

special materials.

3.3 Quality Required:

This generally affects the manufacturing process and ultimately the material. For

example, it would never be desirable to go for casting of a less number of components

which can be fabricated much more economically by welding or hand forging the steel.

3.4 Availability of Material:

Some materials may be scarce or in short supply. It then becomes obligatory for

the designer to use some other material which though may not be a perfect substitute for

the material designed.

The delivery of materials and the delivery date of product should also be kept in

mind.

3.5 Space Consideration:

Sometimes high strength materials have to be selected because the forces involved

are high and the space limitations are there.

3.6 Cost:

As in any other problem, in selection of material the cost of material plays an

important part and should not be ignored.

Some times factors like scrap utilization, appearance, and non-maintenance of the

designed part are involved in the selection of proper materials.

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CHAPTER-4

4. COMPONENTS AND DESCRIPTION

4.1 MAJOR PARTS:

The major parts “PNEUMATIC THREE AXIS MODERN TIPPER” are described

below:

Air compressor

Direction Control Valve

Cylinder

Connecting hoses

Flow control valve

Bearing with bearing cap

Wheel arrangement

Vehicle model frame

Rotating Plates

4.1.1AIR COMPRESSOR:

The main function of the air compressor is to compress the air up to the required

pressure. The maximum capacity of the compressor is 10105 to 12 105 N/m2. This is a

two stages or two-cylinder reciprocating air compressor. The two cylinders are for low

and high compression. The air pressure is measured at various places by the use of

pressure gauges. V-belt and pulley are used to drive the compressor.

Compressors can be broadly classifieds into two groups. They are:

Positive Displacement Compressor

Dynamic Compressors

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4.1.1.1Positive Displacement Compressor:

Successive volumes of air isolated and then compressed to a higher pressure.

There are essential two forms of positive displacement compressor, reciprocating and

rotary.

4.1.1.2Dynamic Compressors:

These are rotary continuous machines in which a high speed rotating element

accelerates the air and converts the resulting velocity head into pressure.

Positive displacement compressors work on the principle of increasing the pressure of

a definite volume in an enclosed chamber. Dynamic (turbo) compressor employs rotating

vanes or impellers to impart velocity and pressure to the flow of the air being handled.

The pressure comes from the dynamic effects such as centrifugal force.

4.1.2 PRESSURE GAUGE:

Pressure gauge is used for measuring the outlet pressure of air from the

compressor. The gauge used is Bourdon type pressure gauge. The maximum capacity of

this gauge is 10 105 to 12 105 N/m2. The gauge is fitted at the outlet of the air

compressor.

4.1.3 DIRECTIONAL CONTROL VALVES:

4.1.3.1 Pneumatic valves:

The pneumatic cylinder is regulated and controlled by pneumatic valves. These

valves are actuated manually, mechanically, electrically, pneumatically, and by various

combined mode of actuation.

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4.1.3.2Need of Valves:

DIRECTIONAL CONTROL VALVES To control the to and fro motion of

cylinder, the fluid energy has to be regulated, controlled and reversed with a

predetermined sequence in a pneumatic system.

Similarly one may have to control the quantity of pressure and flow rate to

generate the desired level of force and speed of actuators. To achieve these functions,

valves are used. Valves are fluid power elements used for controlling and regulating the

working medium.

The main functions of the valves are:

Start and stop the fluid energy

Control the direction of flow of compressed air

Control the flow rate of the fluid

Control the pressure rating of the fluid

Although various types of valves are available, they are mainly classified as below:

Direction control valves

Direction control check valves

Flow control valves

Pressure control valves

The main purpose of a valve in a pneumatic circuit is to control outputs. Valves

can be divided into a number of groups according to what they control.

4.1.3.3 Directional control valves:

Directional control valve on the receipt of some external signal, which might be

mechanical, electrical or a fluid pressure pilot signal, charges the direction of or stops, or

starts the flow of fluid in some part of the pneumatic/hydraulic circuit.

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4.1.3.4 Pressure Control Valves:

These are used to control the pressure in part of the pneumatic/hydraulic circuit.

4.1.3.5 Flow Control Valves:

These are used to control the rate of flow of a fluid through the valve.

A directional control valve on the receipt of some, external signal, which might be

mechanical, electrical or a fluid pilot signal, changes the direction of stops, or starts the

flow of fluid in some part of the pneumatic/hydraulic circuit. They can be used to carry

out such functions as:

1. Controlling the direction of motion of an actuator

2. Selecting alternative flow paths for a fluid.

3. Stopping and starting the flow of fluid.

Carrying out logic functions such as AND, OR, NAND

4.1.3.6 Actuators:

An actuator is a device that is used to apply a force to an object

Fluid power actuators can be classified into two groups:

Linear actuators are used to move an object or apply a force in a straight line.

Linear actuators can be divided into two types.

They are:

1. Single acting cylinders

2. Double acting cylinders

A single acting cylinder is powered by fluid for the movement of the piston in one

direction with it being returned in the other direction by an internal spring or an external

force, a double acting cylinder is powered by fluid in both directions.

Rotary actuators are used to move an object in a circular path. Rotary

actuators are the fluid power equivalent of an electric motor.

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4.1.4 PNEUMATIC CYLINDERS:

Cylinders are the one, which offers the rectilinear motion to mechanical elements.

Cylinders are classified as light, medium, and heavy duty with respect to their

application.

4.1.4.1Single Acting Cylinders:

In this type, the cylinder can produce work only in one direction. The return

movement of the piston is effected by a built in spring or by application of an external

force. The spring is designed to return the piston to its initial position with a sufficiently

high speed.

Types of single acting cylinders:

Diaphragm cylinder

Rolling diaphragm cylinder

4.1.4.2Double Acting Cylinder:

The force exerted by the compressed air moves the piston in two directions in

a double acting cylinder. They are used particularly when the piston is required to

perform work not only on the advance movement but also on the return. In principle, the

stroke length is unlimited, although buckling and bending must be considered before we

select a particular size of piston diameter, rod length and stroke length.

We use cylinders that are double acting type (i.e.) the compressed air can be

passed to either end of the cylinder. These cylinders are made up of cast iron.

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4.1.5 SEALS:

4.1.5.1 Air Seal:

Air seal is used to prevent the leakage of air pressure from the cylinder. Normally

it is made up of neoprene rubber. If there are any air leakages in the system, it will reduce

the efficiency.

4.1.5.2Wiper Seal:

Wiper seal is provided at the entrance of the cylinder to avoid dust materials from

the environment. It is made up of neoprene rubber.

4.1.5.3“O” Ring:

The “O” rings are fitted into the grooves of piston to maintain perfect seal between

the piston and the cylinder wall. They are mostly made up of neoprene rubber.

4.1.6 CYLINDER TECHNICAL DATA:

Barrel:

It is made of cold drawn aluminimum honed to 25mm.

Piston Rod:

M.S. hard Chrome plated

Seals:

Nitrile (Buna – N) Elastomer

End Covers:

Cast iron graded fine grained from 25mm to 300mm

Piston:

Aluminium.

Media:

Air.

Temperature Range:

0^c to 85^c

Cushions:

Adjustable standard on 400mm bore and above.

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4.1.7 CONNECTORS:

In our system there are two types of connectors used; one is the hose connector and

the other is the reducer. Hose connectors normally comprise an adapter (connector) hose

nipple and cap nut. These types of connectors are made up of brass or Aliminium or

hardened steel.

Reducers are used to provide inter connection between two pipes or hoses of

different sizes. They may be fitted straight, tee, “V” or other configurations. These

reducers are made up of gunmetal or other materials like hardened steel etc.

4.1.8 FLOW CONTROL VALVE:

In any fluid power circuit, flow control valve is used to control the speed of the

actuator. The floe control can be achieved By varying the area of flow through which the

air in passing.

When area is increased, more quantity of air will be sent to actuator as a result its

speed will increase. If the quantity of air entering into the actuator is reduced, the speed

of the actuator is reduced.

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4.1.9BEARING WITH BEARING CAP:

The bearings are pressed smoothly to fit into the shafts because if hammered the

bearing may develop cracks. Bearing is made upof steel material and bearing cap is mild

steel.

Ball and roller bearings are used widely in instruments and machines in

order to minimize friction and power loss.  While the concept of the ball bearing

dates back at least to Leonardo da Vinci, their design and manufacture has become

remarkably sophisticated.

This  technology  was  brought  to  its  p resent  state  o f  perfection  only

after  a  long  period  of research and development.  The benefits of such specialized

research can be obtained when it is possible to use a standardized bearing of the

proper size and type.  

However, such bearings cannot be used indiscriminately without a careful

study of the loads and operating conditions.  In addition, the bearing must be

provided with adequate mounting, lubrication and sealing.

4.1.10 WHEEL ARRANGEMENT:

The wheels are fitted to the body of the vehicle with the help of end bearing

and bearing caps. The wheels are made up of fiber material.

4.1.11 TIPPER BODY:

The tipper body is made up of mild steel sheet metal. This frame is look like a

small model trailer.

4.1.12 ROTATING PLATES:

The rotating plates are fixed in the bottom the trailer body, so that the cylinder will

rotates in the required side. The plates are made up of mild steel materials.

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CHAPTER-5

5. BATTERY

5.1 INTRODUCTION:

In isolated systems away from the grid, batteries are used for storage of excess

solar energy converted into electrical energy. The only exceptions are isolated sunshine

load such as irrigation pumps or drinking water supplies for storage. In fact for small

units with output less than one kilowatt. Batteries seem to be the only technically and

economically available storage means. Since both the photo-voltaic system and batteries

are high in capital costs. It is necessary that the overall system be optimized with respect

to available energy and local demand pattern. To be economically attractive the storage

of solar electricity requires a battery with a particular combination of properties:

(1) Low cost

(2) Long life

(3) High reliability

(4) High overall efficiency

(5) Low discharge

(6) Minimum maintenance

(A) Ampere hour efficiency

(B) Watt hour efficiency

We use lead acid battery for storing the electrical energy from the solar panel for

lighting the street and so about the lead acid cells are explained below.

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5.2 LEAD-ACID WET CELL:

Where high values of load current are necessary, the lead-acid cell is the type most

commonly used. The electrolyte is a dilute solution of sulfuric acid (H₂SO₄). In the

application of battery power to start the engine in an auto mobile, for example, the load

current to the starter motor is typically 200 to 400A. One cell has a nominal output of

2.1V, but lead-acid cells are often used in a series combination of three for a 6-V battery

and six for a 12-V battery.

The lead acid cell type is a secondary cell or storage cell, which can be recharged.

The charge and discharge cycle can be repeated many times to restore the output voltage,

as long as the cell is in good physical condition. However, heat with excessive charge

and discharge currents shortened the useful life to about 3 to 5 years for an automobile

battery. Of the different types of secondary cells, the lead-acid type has the highest

output voltage, which allows fewer cells for a specified battery voltage.

5.3 CONSTRUCTION:

Inside a lead-acid battery, the positive and negative electrodes consist of a group

of plates welded to a connecting strap. The plates are immersed in the electrolyte,

consisting of 8 parts of water to 3 parts of concentrated sulfuric acid. Each plate is a grid

or framework, made of a lead-antimony alloy. This construction enables the active

material, which is lead oxide, to be pasted into the grid. In manufacture of the cell, a

forming charge produces the positive and negative electrodes. In the forming process,

the active material in the positive plate is changed to lead peroxide (pbo₂). The negative

electrode is spongy lead (pb).

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17

Automobile batteries are usually shipped dry from the manufacturer. The

electrolyte is put in at the time of installation, and then the battery is charged to from the

plates. With maintenance-free batteries, little or no water need be added in normal

service. Some types are sealed, except for a pressure vent, without provision for adding

water.

The construction parts of battery are shown in figure (6).

5.4 CHEMICAL ACTION:

Sulfuric acid is a combination of hydrogen and sulfate ions. When the cell

discharges, lead peroxide from the positive electrode combines with hydrogen ions to

form water and with sulfate ions to form lead sulfate. Combining lead on the negative

plate with sulfate ions also produces he sulfate. There fore, the net result of discharge is

to produce more water, which dilutes the electrolyte, and to form lead sulfate on the

plates.

As the discharge continues, the sulfate fills the pores of the grids, retarding

circulation of acid in the active material. Lead sulfate is the powder often seen on the

outside terminals of old batteries. When the combination of weak electrolyte and

sulfating on the plate lowers the output of the battery, charging is necessary.

On charge, the external D.C. source reverses the current in the battery. The

reversed direction of ions flows in the electrolyte result in a reversal of the chemical

reactions. Now the lead sulfates on the positive plate reactive with the water and sulfate

ions to produce lead peroxide and sulfuric acid. This action re-forms the positive plates

and makes the electrolyte stronger by adding sulfuric acid.

At the same time, charging enables the lead sulfate on the negative plate to react

with hydrogen ions; this also forms sulfuric acid while reforming lead on the negative

plate to react with hydrogen ions; this also forms currents can restore the cell to full

output, with lead peroxide on the positive plates, spongy lead on the negative plate, and

the required concentration of sulfuric acid in the electrolyte.

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The chemical equation for the lead-acid cell is

Charge

Pb + pbO₂ + 2H₂SO₄ 2pbSO₄ + 2H₂O

Discharge

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On discharge, the pb and pbo₂ combine with the SO₄ ions at the left side of the

equation to form lead sulfate (pbSO₄) and water (H₂O) at the right side of the equation.

One battery consists of 6 cell, each have an output voltage of 2.1V, which are connected

in series to get an voltage of 12V and the same 12V battery is connected in series, to get

an 24 V battery. They are placed in the water proof iron casing box.

5.5 CARING FOR LEAD-ACID BATTERIES:

Always use extreme caution when handling batteries and electrolyte. Wear

gloves, goggles and old clothes. “Battery acid” will burn skin and eyes and destroy

cotton and wool clothing.

The quickest way of ruin lead-acid batteries is to discharge them deeply and leave

them stand “dead” for an extended period of time. When they discharge, there is a

chemical change in the positive plates of the battery. They change from lead oxide when

charge out lead sulfate when discharged. If they remain in the lead Sulfate State for a

few days, some part of the plate dose not returns to lead oxide when the battery is

recharged. If the battery remains discharge longer, a greater amount of the positive plate

will remain lead sulfate. The parts of the plates that become “sulfate” no longer store

energy. Batteries that are deeply discharged, and then charged partially on a regular basis

can fail in less then one year. Check your batteries on a regular basis to be sure they are

getting charged. Use a hydrometer to check the specific gravity of your lead acid

batteries. If batteries are cycled very deeply and then recharged quickly, the specific

gravity reading will be lower than it should because the electrolyte at the top of the

battery may not have mixed with the “charged” electrolyte.

Check the electrolyte level in the wet-cell batteries at the least four times a year

and top each cell of with distilled water. Do not add water to discharged batteries.

Electrolyte is absorbed when batteries are very discharged. If you add water at this time,

and then recharge the battery, electrolyte will overflow and make a mess.

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Keep the top of your batteries clean and check that cables are tight. Do not tighten

or remove cables while charging or discharging. Any spark around batteries can cause a

hydrogen explosion inside, and ruin one of the cells, and you.

On charge, with reverse current through the electrolyte, the chemical action is

reversed. Then the pb ions from the lead sulfate on the right side of the equation re-form

the lead and lead peroxide electrodes. Also the SO₄ ions combine with H₂ ions from the

water to produce more sulfuric acid at the left side of the equation.

5.6 CURRENT RATINGS:

Lead-acid batteries are generally rated in terms of how much discharge currents

they can supply for a specified period of time; the output voltage must be maintained

above a minimum level, which is 1.5 to 1.8V per cell. A common rating is ampere-hours

(A.h.) based on a specific discharge time, which is often 8h. Typical values for

automobile batteries are 100 to 300 A.h.

As an example, a 200 A.h battery can supply a load current of 200/8 or 25A, used

on 8h discharge. The battery can supply less current for a longer time or more current for

a shorter time. Automobile batteries may be rated for “cold cranking power”, which is

related to the job of starting the engine. A typical rating is 450A for 30s at a temperature

of 0 degree F.

Note that the ampere-hour unit specifies coulombs of charge. For instance, 200

A.h. corresponds to 200A*3600s (1h=3600s). the equals 720,000 A.S, or coulombs.

One ampere-second is equal to one coulomb. Then the charge equals 720,000 or

7.2*10^5ºC. To put this much charge back into the battery would require 20 hours with a

charging current of 10A.

The ratings for lead-acid batteries are given for a temperature range of 77 to 80ºF.

Higher temperature increase the chemical reaction, but operation above 110ºF shortens

the battery life.

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Low temperatures reduce the current capacity and voltage output. The ampere-

hour capacity is reduced approximately 0.75% for each decreases of 1º F below normal

temperature rating. At 0ºF the available output is only 60 % of the ampere-hour battery

rating. In cold weather, therefore, it is very important to have an automobile battery unto

full charge. In addition, the electrolyte freezes more easily when diluted by water in the

discharged condition.

5.8 CHARGING THE LEAD-ACID BATERY:

The requirements are illustrated in figure. An external D.C. voltage source is

necessary to produce current in one direction. Also, the charging voltage must be more

than the battery e.m.f.

Approximately 2.5 per cell are enough to over the cell e.m.f. so that the charging

voltage can produce current opposite to the direction of discharge current. Note that the

reversal of current is obtained just by connecting the battery VB and charging source VG

with + to + and –to-, as shown in figure. The charging current is reversed because the

battery effectively becomes a load resistance for VG when it higher than VB. In this

example, the net voltage available to produce charging currents is 15-12=3V. A

commercial charger for automobile batteries is essentially a D.C. power supply,

rectifying input from the AC power line to provide D.C. output for charging batteries.

Float charging refers to a method in which the charger and the battery are always

connected to each other for supplying current to the load. In figure the charger provides

current for the load and the current necessary to keep the battery fully charged. The

battery here is an auxiliary source for D.C. power.

It may be of interest to note that an automobile battery is in a floating-charge

circuit. The battery charger is an AC generator or alternator with rectifier diodes, driver

by a belt from the engine. When you start the car, the battery supplies the cranking

power. Once the engine is running, the alternator charges he battery. It is not necessary

for the car to be moving. A voltage regulator is used in this system to maintain the output

at approximately 13 to 15 V.

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The constant voltage of 24V comes from the solar panel controlled by the charge

controller so for storing this energy we need a 24V battery so two 12V battery are

connected in series. It is a good idea to do an equalizing charge when some cells show a

variation of 0.05 specific gravity from each other. This is a long steady overcharge,

bringing the battery to a gassing or bubbling state. Do not equalize sealed or gel type

batteries. With proper care, lead-acid batteries will have a long service life and work very

well in almost any power system. Unfortunately, with poor treatment lead-acid battery

life will be very short.

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CHAPTER-6

6. D.C MOTOR

6.1 INTRODUCTION:

The electrical motor is an instrument, which converts electrical energy into

mechanical energy. According to faraday’s law of Electro magnetic induction, when a

current carrying conductor is placed in a magnetic field, it experiences a mechanical force

whose direction is given by Fleming’s left hand rule.

Constructional a dc generator and a dc motor are identical. The same dc machine

can be used as a generator or as a motor. When a generator is in operation, it is driven

mechanically and develops a voltage. The voltage is capable of sending current through

the load resistance. While motor action a torque is developed.

The torque can produce mechanical rotation. Motors are classified as series

wound, shunt wound motors.

6.2 Principles of operation:

The basic principle of Motor action lies in a sample sketch.

Movement of

Conductor

Magnetic flux current carrying

Conductor

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N S

The motor run’s according to the principle of Fleming’s left hand rule. When a

current carrying conductor is placed in a magnetic field is produced to move the

conductor away from the magnetic field.

The conductor carrying current to North and South poles is being removed. In the

above stated two conditions there is no movement of the conductors. Whenever a current

carrying conductor is placed in a magnetic field. The field due to the current in the

conductor but opposes the main field below the conductor. As a result the flux density

below the conductor. It is found that a force acts on the conductor to push the conductor

downwards.

If the current in the conductor is reversed, the strengthening of the flux lines

occurs below the conductor, and the conductor will be pushed upwards.

As stated above the coil side A will be forced to move downwards, where as the

coil side B will be forced to move upwards. The forces acting on the coil sides A and B

will be the same coil magnitudes, but their directions will be opposite to one another. In

DC machines coils are wound on the armature core, which is supported by the bearings,

enhances rotation of the armature. The commutator periodically reverses the direction of

current flow through the armature. Thus the armature rotates continuously.

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An electric motor is all about magnets and magnetism: a motor uses magnets to

create motion. If you have ever played with magnets you know about the fundamental

law of all magnets: Opposites attract and likes repel.

So if you have 2 bar magnets with their ends marked north and south, then the

North end of one magnet will attract the South end of the other. On the other hand, the

North end of one magnet will repel the North end of the other (and similarly south will

repel south). Inside an electric motor these attracting and repelling forces create rotational

motion.

In the diagram above and below you can see two magnets in the motor, the

armature (or rotor) is an electromagnet, while the field magnet is a permanent magnet

(the field magnet could be an electromagnet as well, but in most small motors it is not to

save power).

6.3 Electromagnets and Motors:

To understand how an electric motor works, the key is to understand how the

electromagnet works. An electromagnet is the basis of an electric motor. You can

understand how things work in the motor by imagining the following scenario.

Say that you created a simple electromagnet by wrapping 100 loops of wire

around a nail and connecting it to a battery. The nail would become a magnet and have a

North and South pole while the battery is connected. Now say that you take your nail

electromagnet, run an axle through the middle of it, and you suspended it in the middle of

a horseshoe magnet as shown in the figure below.

If you were to attach a battery to the electromagnet so that the North end of the

nail appeared as shown, the basic law of magnetism tells you what would happen:

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The North end of the electromagnet would be repelled from the north end of the

horseshoe magnet and attracted to the south end of the horseshoe magnet.

The South end of the electromagnet would be repelled in a similar way. The nail

would move about half a turn and then stop in the position shown.

You can see that this half-turn of motion is simple and obvious because of

the way magnets naturally attract and repel one another. The key to an electric motor is to

then go one step further so that, at the moment that this half-turn of motion completes, the

field of the electromagnet flips.

The flip causes the electromagnet to complete another half-turn of motion. You

flip the magnetic field simply by changing the direction of the electrons flowing in the

wire (you do that by flipping the battery over). If the field of the electromagnet flipped at

just the right moment at the end of each half-turn of motion, the electric motor would

spin freely.

The Armature:

The armature takes the place of the nail in an electric motor. The armature is an

electromagnet made by coiling thin wire around two or more poles of a metal core. The

armature has an axle, and the commutator is attached to the axle. In the diagram above

you can see three different views of the same armature: front, side and end-on. In the end-

on view the winding is eliminated to make the commutator more obvious. You can see

that the commutator is simply a pair of plates attached to the axle. These plates provide

the two connections for the coil of the electromagnet.

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6.4 The Commutator and brushes:

The "flipping the electric field" part of an electric motor is accomplished by two

parts: the commutator and the brushes.

The diagram at the right shows how the commutator and brushes work together to

let current flow to the electromagnet, and also to flip the direction that the electrons are

flowing at just the right moment.

The contacts of the commutator are attached to the axle of the electromagnet, so

they spin with the magnet. The brushes are just two pieces of springy metal or carbon that

make contact with the contacts of the commutator.

Putting It All Together:

When you put all of these parts together, what you have is a complete electric motor:

In this figure, the armature winding has been left out so that it is easier to see the

commutator in action. The key thing to notice is that as the armature passes through the

horizontal position, the poles of the electromagnet flip.

Because of the flip, the North pole of the electromagnet is always above the axle

so it can repel the field magnet's North pole and attract the field magnet's South pole.

If you ever take apart an electric motor you will find that it contains the same

pieces described above: two small permanent magnets, a commutator, two brushes and an

29

electromagnet made by winding wire around a piece of metal. Almost always, however,

the rotor will have three poles rather than the two poles as shown in this article. There are

two good reasons for a motor to have three poles:

It causes the motor to have better dynamics. In a two-pole motor, if the

electromagnet is at the balance point, perfectly horizontal between the two poles of

the field magnet when the motor starts; you can imagine the armature getting

"stuck" there. That never happens in a three-pole motor.

Each time the commutator hits the point where it flips the field in a two-pole

motor, the commutator shorts out the battery (directly connects the positive and

negative terminals) for a moment. This shorting wastes energy and drains the

battery needlessly. A three-pole motor solves this problem as well.

It is possible to have any number of poles, depending on the size of the motor and

the specific application it is being used in.

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CHAPTER-7

7. DESIGN AND DRAWINGS

7.1PNEUMATIC CYLINDER

7.1.1 Design of Piston rod:

Load due to air Pressure.

Diameter of the Piston (d) = 40 mm

Pressure acting (p) = 6 kgf/cm²

= 6 ×0.981

= 5.886 bar

= 0.5886N/mm2

Material used for rod = C 45

(data book page no 1.12 )

Yield stress (σy) = 36 kgf/mm²

= 36×98.1

= 3531.6 bar

= 353.16N/mm2

factor of safety = 2( data book page.no 8.19)

Force acting on the rod (F) = Pressure x Area

= p x (Πd² / 4)

= 0.5886 x {( Π x 40² ) / 4 }

F = 739.6 N

Design Stress(σy) = σy / F0 S

= 353.16 / 2

= 176.5N/mm2

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∴d = √4F/π [σy]

= √ (4×739.6)/ π[176.5]

∴ Minimum diameter of rod required for the load = 2.3 mm

We assume diameter of the rod = 15 mm

7.1.2 Design of cylinder thickness:

Material used = Cast iron

Assuming internal diameter of the cylinder = 40 mm

Ultimate tensile stress = 250 N/mm²

Working Stress = Ultimate tensile stress / factor of safety

Assuming factor of safety = 4

Working stress ( ft ) = 250 / 4

= 62.5 N/mm2

According to ‘LAMES EQUATION’

Minimum thickness of cylinder ( t ) = ri {√(f t+p)/(ft-p)-1}

Where,

ri = inner radius of cylinder in cm.

ft = Working stress (N/mm²)

p = Working pressure in N/mm²

∴ Substituting values we get,

t = 2.0 {√ (62.5 + 0.5886) / (62.5 – 0.5886) -1}

t = 0.27mm

We assume thickness of cylinder = 2.5 mm

Inner diameter of barrel = 40 mm

Outer diameter of barrel = 40 + 2t

= 40 + ( 2 x 2.5 )

= 45 mm

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7.2 DESIGN OF PISTON ROD:

7.2.1 Diameter of Piston Rod:

Force of piston Rod (F) = Pressure x area

= p x Π/4 (d²)

= 0.5886 x (Π / 4) x (40)²

= 739.6 N

Also, force on piston rod (F) = (Π/4) (dp)² x ft

F = (Π/4) x (dp)² x 62.5

739.6 = (Π/4) x (dp)² x 625

∴ dp² = 739.6 x (4/Π) x (1/62.5)

= 15

dp = 3.8 mm

By standardizing dp = 15 mm

7.2.2 Length of piston rod:

Approach stroke = 160 mm

Length of threads = 2 x 20 = 40mm

Extra length due to front cover = 12 mm

Extra length of accommodate head = 20 mm

Total length of the piston rod = 160 + 40 + 12 + 20

= 232 mm

By standardizing, length of the piston rod = 230 mm

7.3 DESIGN OF BALL BEARING:

Bearing No. 6202 (Data book page.no 4.13)

Outer Diameter of Bearing (D) = 35 mm

Thickness of Bearing (B) = 12 mm

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Inner Diameter of the Bearing (d) = 15 mm

r₁ = Corner radii on shaft and housing

r₁ = 1(From design data book)

Maximum Speed = 14,000 rpm (From design data book)

Mean Diameter (dm) = (D + d) / 2

= (35 + 15) / 2

dm = 25 mm

7.4 WAHL STRESS FACTOR:

(From design data book page.no 7.100)

Ks = 4C – 1 + 0.65

4C – 4 C

= (4 X 2.3) -1 + 0.65

(4 X 2.3 )-4 2.3

Ks = 1.85

7.5SPECIFICATION

7.5.1 Double acting pneumatic cylinder

Technical Data

34

Stroke length : Cylinder stoker length 160 mm = 0.16 m

Quantity : 1

Seals : Nitride (Buna-N) Elastomer

End cones : Cast iron

Piston : EN – 8

Media : Air

Temperature : 0-80 º C

Pressure Range : 8 N/m²

7.5.2 Flow control Valve

Technical Data

Port size : 0.635 x 10 ֿ² m

Pressure : 0-8 x 10 ⁵ N/m²

Media : Air

Quantity : 1

7.5.3 Connectors

Technical data

Max working pressure : 10 x 10 ⁵ N/m²

Temperature : 0-100 º C

Fluid media : Air

Material : Brass

7.5.4 Hoses

Technical date

Max pressure : 10 x 10 ⁵ N/m²

35

Outer diameter : 6 mm = 6 x 10 ˉ ³m

Inner diameter : 3.5 mm = 3.5 x 10 ˉ ³m

36

37

38

CHAPTER-8

8. WORKING PRINCIPLE

Since pneumatic circuit plays a vital role in this device, it is very necessary to

explain the working of this circuit.

Initially starting with air compresses, its function is to compress air from a low

inlet pressure (usually atmospheric) to a higher pressure level. This is an accomplished

by reducing the volume of the air.

Air compressors are generally positive displacement units and are either of the

reciprocating piston type or the rotary screw or rotary vane types. The air compressor

used here is a typically small sized, two-stage compressor unit. It also consists of a

compressed air tank, electric rotor and pulley drive, pressure controls and instruments for

quick hook up and use. The compressor is driver by a 1 HP motor and designed to

operate in 10 – 100 PSI range. If the pressure exceeds the designed pressure of the

receiver a release value provided releases the excesses air and thus stays a head of any

hazards to take place.

Then having a pressure regulator where the desired pressure to the operated is set.

Here a variable pressure regulator is adopted. Through a variety of direction control value

are available, a hand operated spool value with detent is applied.

The spool value used here is 5 ports, 3 positions. There are two exhaust ports, two

outlet ports and one inlet port. In two extreme positions only the directions can be

changed while the Centro ore is a neutral position and no physical changes are incurred.

The 2 outlet ports are connected to an actuator (Cylinder). The pneumatic

activates is a double acting, single rod cylinder. The cylinder output is coupled to further

purpose. The piston end has an air horning effect to prevent sudden thrust at extreme

ends.

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8.1 PRINCIPLES OF WORKING

The compressed air from the compressor reaches the direction control valve. The

direction control valve changes the direction of flow according to the valve

position handle.

The compressed air pass through the direction control valve and it is admitted into

the front end of the cylinder block. The air pushes the piston for the lifting stroke.

At the end of the lifting stroke air from the valve reaches the rear end of the

cylinder block. The pressure remains the same but the area is less due to the

presence of piston rod. This exerts greater pressure on the piston, pushing it at a

faster rate thus enabling faster return stroke.

The stroke length of the piston can be changed by making suitable adjustment in

the hand liver valve operating position.

40

CHAPTER-9

ADVANTAGES, DISADVANTAGES AND APPLICATIONS

9.1 ADVANTAGES:-

It requires simple maintenance cares

Checking and cleaning are easy, because of the main parts are screwed.

Handling is easy.

Manual power not required

Repairing is easy.

Replacement of parts is easy.

9.2 DISADVANTAGES

Initial cost is high.

Separate air tank or compressor is required.

9.3 APPLICATIONS

All hydraulic and pneumatic dipper applications.

Easy to unload the materials

41

CHAPTER-10

10. LIST OF MATERIALS

Sl. No. PARTS Qty. Material

i. Pneumatic Double Acting Cylinder 1 M.S

ii. 5/2 Direction Control Valve 1 Aluminium

iii. Battery 1 Electronics

iv. Wheel 4 Rubber

v. Bearing with Bearing Cap 4 Fiber

vi. Polyethylene Tube - Polyurethene

vii. Hose Collar and Reducer - Brass

Viii Stand (Frame) 1 Mild steel

Ix Dash Pad 1 Plastic

X D.C Motor 1 Aluminum

Xi Flow control valve 1 Lead-Acid

42

CHAPTER-11

11. COST ESTIMATION

11.1MATERIAL COST:

Sl. No. PARTS Qty. Material Amount (Rs)

i. Pneumatic Double Acting

Cylinder

1 M.S 1200

ii. 5/2 Direction Control Valve 1 Aluminium 500

iii. Battery 1 Electronics 850

iv. Wheel 4 Rubber 200

v. Bearing with Bearing Cap 4 Fiber 150

vi. Polyethylene Tube - Polyurethene 100

vii. Hose Collar and Reducer - Brass 250

Viii Stand (Frame) 1 Mild steel 650

Ix Dash Pad 1 Plastic 200

X D.C Motor 1 Aluminum 700

Xi Flow control valve 1 Lead-Acid 350

TOTAL = 5150

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CHAPTER-12

12. CONCLUSION

This project work has provided us an excellent opportunity and experience, to use

our limited knowledge. We gained a lot of practical knowledge regarding, planning,

purchasing, assembling and machining while doing this project work. We feel that the

project work is a good solution to bridge the gates between institution and industries.

We are proud that we have completed the work with the limited time successfully.

The “THREE AXIS PNEUMATIC MODERN TIPPER” is working with satisfactory

conditions. We are able to understand the difficulties in maintaining the tolerances and

also quality. We have done to our ability and skill making maximum use of available

facilities. In conclusion remarks of our project work, let us add a few more lines about

our impression project work.

Thus we have developed a “THREE AXIS PNEUMATIC MODERN

TIPPER” which helps to know how to achieve low cost automation. The operating

procedure of this system is very simple, so any person can operate. By using more

techniques, they can be modified and developed according to the applications.

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BIBLIOGRAPHY

1. G.B.S. Narang, “Automobile Engineering”, Khanna Publishers, Delhi, 1991,

pp 671.

2. William H. Crowse, “Automobile Engineering”.

3. MECHANISMS IN MODERN ENGINEERING DESIGN Vol. V. PART I

4. ELEMENTS OF WORKSHOP TECHNOLOGY – VOL II

-S.K. HAJRA CHOUDHURY

-S.K. BOSE

-A.K. HAJRA CHOUDHERY

5. STRENGTH OF MATERIALS -I.B. PRASAD

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