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FABRICATION OF ELECTROMAGNETIC BRAKING SYSTEM
Submitted in the partial fulfillment of the requirement for the award of
“DIPLOMA IN AUTOMOBILE ENGINEERING ”
SUBMITTED BY:
1. G.K. MANIGANDAN 4. J. DHANAJEYAN 2. B. KARTHIKEYAN 5. D. DURAIVEL 3. P. BALASUBRAMANI 6. L. PRABHU
Under guidance of
Mr. V.K. RAJENDRAN,M.E.
MARCH 2013.
DEPARTMENT OF AUTOMOBILE ENGINEERING
A M K TECHNOLOGICAL POLYTECHNIC COLLEGECHEM BARAMBAKKAM, CHENNAI – 602 103
A M K TECHNOLOGICAL POLYTECHNIC COLLEGECHEM BARAMBAKKAM, CHENNAI – 602 103
BONAFIDE CERTIFICATE
This is to certify that this Project work on
“FABRICATION OF ELECTROMAGNETIC BRAKING SYSTEM”
submitted by …………………… ……………. Reg. No. ……………
in partial fulfillment for the award of
DIPLOMA IN AUTOMOBIL ENGINEERING
This is the bonafide record of work carried out by him under
our supervision during the year 2013
Submitted for the Viva-voce exam held on ……………..
HEAD OF THE DEPARTMENT PROJECT GUIDE
INTERNAL EXAMINER EXTERNAL EXAMINER
ACKNOWLEDGEMENT
ACKNOWLEDGEMENT
At the outset, we would like to emphasize our sincere thanks to the
Principal Mr. A.VIJAY KISHORE M.TECH MISTE.,., encouragement
and valuable advice.
we thank our Esquired Head of Department Mr R. RAJKUMAR,
A.M.I.E, M.E., for presenting his felicitations on us.
We are grateful on our Entourages Mr.S,MURALI M.E., for
guiding in various aspects of the project making it a grand success.
We also owe our sincere thanks to all staff members of the
Mechanical Engineering (MTMR) Department.
Ultimately, we extend our thanks to all who had rendered their co-
operation for the success of the project.
CONTENTS
CONTENTS
Chapter No. TITLE
1. INTRODUCTION
2. SYNOPSIS
3. CONSTRUCTION
4. WORKING PRINCIPLE
5. BRAKE CIRCUIT DIAGRAM
6. MECHANICAL SPARE PARTS DETAILS
7. ELECTRICAL PARTS DETAILS
8. ELECTRICAL CIRCUIT DETAILS
9. FINISHING AND PAINTING
10. COST ESTIMATION
11. CONCLUSION
12. BIBILOGRAPHY
INTRODUCTION
INTRODUCTION
This is a self – assessment test on the part of the students to assess his
competency in creativity.
During the course of study, the student is put on a sound theoretical
foundation of various mechanical engineering subjects and of course, to a
satisfactory extent. Opportunities are made available to him to work on
different kinds of machines, so that he is exposed to various kinds of
manufacturing process.
As a students learn more and more his hold on production technology
becomes stronger. He attains a stage of perfection, when he himself is able
to design and fabricate a device.
This is the project work. That is the testimony for the strenuous
training, which the student had in the institute. This assures that he is no
more a student, he is an engineer.
This report discuses the necessity of the project and various aspects of
planning , design, selection of materials, fabrication, erection, estimation and
testing.
SYNOPSIS
SYNOPSIS
Electric brakes a type of the braking system not very popular
can be used commercially in passenger cars as they have several advantages.
Electromagnetic brakes are used in other fields such as bottling plants. They
are used for bringing the assembly to a quick stop each time for filling up the
bottles. In this project we propose to deal with a new type of electromagnetic
brake using solenoid switch. Most magnetic breaking relay on the attractive
force generated within a gap magnetic circuit which generates forces on the
supported shaft because this force is quadratic magnetic flux intensity in the
circuit: it is only possible to pull the shaft to accomplish bi or
multidirectional control of the shaft.
Several electromagnets are arranged around the shaft and are operated
differentially to improve the linearity and dynamic performance of these
differentially arranged magnets. It is commons to free bias the air gaps with
constant flux density. This biasing can be accomplished in a number of ways
but usually it is done by applying a biasing current to the oils, which
energize the magnetic circuits. The primary advantages of this scheme a
reduction in electrical power consumption. Magnetic bearings employ the
repulsive forces of opposed magnetic fields generated by electromagnets in
this slider and the base. They achieve straight line accuracy to 0.00004-
inches / foot through a control loop that employs capacity, proximately
sensos in position feed back for controlling the amplifiers that generate the
magnetic fields. Magnetic breaking can support loads in excess of 1000
pounds, magnetic Breaking have no moving parts to wear and can be used in
vacuum condition soothers is no friction in contact places.
The electro magnetic brake operates in 12VDC power supply. When the
supply given to the electromagnetic coil which pulls the brake lever to apply
the brake to the rotating wheel.
Block Diagram;
DC Power Supply
ELECTRO MAGNETIC BRAKE
Switch to apply brake
Brake lever
Wheel
CONTRUCTION
CONTRUCTION
This unit consists of
1) M.S. FABRICATED STAND UNIT
2) DC POWER SUPPLY WITH SWITCH
3) ELECTROMAGNETIC COIL UNIT
4) BRAKING UNIT
1)M.S. FABRICATED STAND UNIT ;
The rear wheel for two wheeler bike is dismantled and mounted in the M.S.
fabricated stand. This stand is made in 25x25x 3 mm size L angle. In this
electromagnetic coil unit is fitted . this solenoid coil has one central iron rod
which is connected to brake drum lever against spring force control.
2)DC POWER SUPPLY WITH SWITCH
POWER SUPPLY 5V DC AND 12V DC;
A 12 –0 v step down transformer is used to stepdown 230V AC to
12V AC .This 12V AC supply is converted to 12V DC using four rectifier
diodes. The voltage from the rectifier section is regulated to 12V DC using
7812 IC . From 12V DC the 7805 IC is used for regulating 5V DC for the
power supply of microcontroller.
the power supply circuit is shown in fig.
3. POWER SUPPLY UNIT ;
INTRODUCTION:
All the electronic components starting from diode to Intel IC’s only
work with a DC supply ranging from +5V to +12V. We are utilizing for the
same, the cheapest and commonly available energy source of 230V-50Hz
and stepping down, rectifying, filtering and regulating the voltage.
STEP DOWN TRANSFORMER:
When AC is applied to the primary winding of the power transformer,
it can either be stepped down or stepped up depending on the value of DC
needed. In our circuit the transformer of 230V/15-0-15V is used to perform
the step down operation where a 230V AC appears as 15V AC across the
secondary winding. Apart from stepping down voltages, it gives isolation
between the power source and power supply circuitries.
RECTIFIER UNIT:
In the power supply unit, rectification is normally achieved using a
solid state diode. Diode has the property that will let the electron flow easily
in one direction at proper biasing condition. As AC is applied to the diode,
electrons only flow when the anode and cathode is negative. Reversing the
polarity of voltage will not permit electron flow. A commonly used circuit
for supplying large amounts of DCpower is the bridge rectifier. A bridge
rectifier of four diodes (4 x IN4007) are used to achieve full wave
rectification. Two diodes will conduct during the negative cycle and the
other two will conduct during the positive half cycle, and only one diode
conducts. At the same time one of the other two diodes conducts for the
negative voltage that is applied from the bottom winding due to the forward
bias for that diode. In this circuit due to positive half cycle D1 & D2 will
conduct to give 0.8V pulsating DC. The DC output has a ripple frequency
of 100Hz. Since each alteration produces a resulting output pulse, frequency
= 2 x 50 Hz. The output obtained is not a pure DC and therefore filtration
has to be done.
The DC voltage appearing across the output terminals of the bridge
rectifier will be somewhat less than 90% of the applied rms value. Normally
one alteration of the input voltage will reverse the polarities. Opposite ends
of the transformer will therefore always be 180 degree out of phase with
each other. For a positive cycle, two diodes are connected to the positive
voltage at the top winding.
3)ELECTROMAGNETIC COIL UNIT;
This unit having one solenoid coil operated in 12VDC supply voltage.
There is a metal rod centrally mounted in the coil under spring force. When
the supply is given to the coil unit ,the solenoid core rod moves inward in
to the coil and the metal rod pull the brake lever pedal downward
direction. This coil is connected to the power supply through a button.
4)BRAKING UNIT
Drum brakes consist of a backing plate, brake shoes, brake drum, wheel
cylinder, return springs and an automatic or self-adjusting system. When you
apply the brakes, brake fluid is forced, under pressure, into the wheel
cylinder which, in turn, pushes the brake shoes into contact with the
machined surface on the inside of the drum. When the pressure is released,
return springs pull the shoes back to their rest position. As the brake linings
wear, the shoes must travel a greater distance to reach the drum. When the
distance reaches a certain point, a self-adjusting mechanism automatically
reacts by adjusting the rest position of the shoes so that they are closer to the
drum.
WORKING OPERATION
WORKING OPERATION
. In this project we propose to deal with a new type of electromagnetic
brake using solenoid switch.
This unit having one solenoid coil operated in 12VDC supply
voltage. There is a metal rod centrally mounted in the coil under spring
force. When the supply is given to the coil unit ,the solenoid core rod moves
inward in to the coil and the metal rod pull the brake lever pedal
downward direction. This coil is connected to the power supply through a
button.
The electro magnetic brake operates in 12VDC power supply. When the
supply given to the electromagnetic coil which pulls the brake lever to apply
the brake to the rotating wheel.
Block Diagram;
DC Power Supply
ELECTRO MAGNETIC BRAKE
Switch to apply brake
Brake lever
Wheel
ADVANTAGE
ADVANTAGE ;
1. Easy to install and low cost.
2. Repair and maintenance is simple.
3. It is used as a safety device duo to over load
DISADVANTAGES
DISADVANTAGES
1. Braking speed is constant
2. This braking is not a smooth one.
3. High battery power is required.
4. May be chance of electro-magnetic coil failure.
APPLICATIONS
APPLICATIONS
1. Used in machinetool spindle gear box system to change the speed.
2. Used in crane control system
3. Used in winch controlling
4. Used in lift controlling
5. Used in automobile purpose
BASIC REQUIREMENTS
OF A BRAKE
BASIC REQUIREMENTS OF A BRAKE:
The brake must be strong enough to stop the vehicle with a minimum
distance. The distance should be the shortest during Emergency braking. The
distance moved by the vehicle after the application of the brake is known as
braking.
The brakes must have good ant fade characteristic. In other words the
brakes should not loose their effectiveness on prolonged application. This is
only possible by proper and effective cooling of brakes.
PURPOSE OF BRAKES
PURPOSE OF BRAKES:
1. To control the speed of the vehicle as well as to stop it when and
where desired quickly and efficiently without sticking.
2. To keep the vehicle is any possible position after it had been actually
brought to a complete rest when the driver is not present.
3. These purposes are accomplished by providing two independent
braking systems in a motor vehicle service brake and a parking (or)
emergency on hand brake.
PRINCIPLES OF
BRAKING
PRINCIPLES OF BRAKING:
The principle of braking is the reverse of that applied during
accelerating a vehicle. in accelerating, the heat energy of the fuel is
converted into the power of kinetic energy is converted into heat by means
of friction produced between low mating surface of the brake drum. similar
to the effective effort produced at the peripheries of the driving of the motor
vehicle, the braking torque introduced at the brakes drums due to application
of brake produces a retarding effort (or) a negative attractive effort is limited
bay the adhesion available between the brake lining and the brake drum
similar to the limit providing by the adhesion available between the wheels
and the grant. the force of friction (or) force exerted on the shoes by the
retarding mechanism and the co-efficient of friction for the two materials.
BRAKE TESTING:
BRAKE TESTING:
When the vehicle is moving, it can be stopped by applying the brakes.
It is to be noted here that brake pedals cannot be passed instantaneously and
the vehicle cannot be stopped instantaneously. First the drive thinks, then lift
the leg., presses the brake pedal and the vehicle stops after moving some
distance. So it is necessary to note how much time is required to stop the
vehicle and how long it will travel after applying the brake. These two
factors are directly dependent on the speed o the vehicle.
STOP TEST:
For testing the brakes, this test is usually adopted by mechanical or
driver after overhauling the brakes the moves the vehicle at a speed and
suddenly applies the brakes. Then he checks how much time it has taken to
stop and how long it has moved after spring the brakes. Also, he sees the
impressions of the four tyres on the road, whether equal or not, and whether
the vehicle is pulling a side or not.
STOP WATCH TEST:
To perform this test, the vehicle is moved at about 70km/hr. then the
brakes are applied. The time and distance are noted.
Let T = time taken to stop the vehicle after applying the brakes.
D = distance moved by the vehicle after applying the brakes.
Then, brake efficiency is given by
N = (D-T2)*6 ¼
Brake testers are also used for testing the brakes. They work on the principle
of decelerometer. Taply brake meter is a type of brake tester. This brake
meter is placed on the vehicle floor for testing the brakes. It consists of a
round ring with numbers. There is a pendulum inside the dial which remain
dipped in oil. As soon as the brake are applied, the vehicle speed decreases
which causes the pendulum ring to move. The number on the ring gives
reading which can be obtained by an inspection plate.
BRAKE SERVICE
BRAKE SERVICE:
Following is the procedure to service the brakes
1. Check the fluid level in the master cylinder
2. Check brake pedal adjustments.
3. Check brake pedal travel: If the pedal travels more than halfway to the
floor, the brakes may require adjusting to compensate for lining wear
or they may be require relining.
4. If the brakes pull to one side after adjustment, check tyre pressure. All
tyros must be inflated to recommended pressures to ensure even
braking. Check brake linings for foreign materials and clean as
required. If the side pull persists, check from wheel alignment and
balance.
5. Check the bake system for leaks by applying a steady pressure on the
break pedal. If the pedal falls away the break system has leak
somewhere. Find the leak points and remove them.
6. A spongy brake pedal indicates the presence of air in the hydraulic
system. This condition must be corrected by bleeding the brakes.
7. If the brakes become locked so that the vehicle cannot be moved the
brakes must be released by opening, the bleeder screw on any one of
the wheel cylinders.
DESCRIPTION OF BRAKE SYSTEM
CHAPTER – 1
DESCRIPTION OF BRAKE SYSTEM
1.1 INTRODUCTION
1.1 INTRODUCTION
Brakes are one of the most important control components of the
vehicle. They are required to stop the vehicle within the smallest possible
distance and this is done by converting the kinetic energy of the wheels into
the heat energy which is dissipated into the atmosphere.
Types of brakes based on method of actuation:
1. Mechanical brakes
2. Hydraulic brakes
3. Electric and electronic brakes
4. Vacuum brakes
5. Air brakes
Types of brakes based on application
1. Drum brakes
2. Disc brakes
3. Parking Brakes
1.2 DRUM BRAKES
The modern automobile drum brake was invented in 1902 by Louis
Renault, though a less - sophisticated drum brake had been used by
Maybach a year earlier. In the first drum brakes, the shoes were
mechanically operated with levers and rods or cables. From the mid-1930s
the shoes were operated with oil pressure in a small wheel cylinder and
pistons, though some vehicles continued with purely-mechanical systems for
decades. Some designs have two wheel cylinders.
The shoes in drum brakes are subject to wear and the brakes needed to be
adjusted regularly until the introduction of self adjusting drum brakes in the
1950s. In the 1960s and 1970s brake drums on the front wheel of cars were
gradually replaced with disc brakes and now practically all cars use disc
brakes on the front wheels, with many offering disc brakes on all wheels.
However, drum brakes are still often used for handbrakes as it has proved
very difficult to design a disc brake suitable for holding a car when it is not
in use. Moreover, it is very easy to fit a drum handbrake inside a disc brake
so that one unit serves for both footbrake and handbrake.
Early type brake shoes contained asbestos. When working on brake
systems of older cars, care must be taken not to inhale any dust present in
the brake assembly. The United States Federal Government began to
regulate asbestos production, and brake manufactures had to switch to non-
asbestos linings. Owners initially complained of poor braking with the
replacements; however, technology eventually advanced to compensate. A
majority of daily-driven older vehicles have been fitted with asbestos-free
linings. Many other countries also limit the use of asbestos in brakes.
Drum brakes consist of a backing plate, brake shoes, brake drum,
wheel cylinder, return springs and an automatic or self-adjusting system.
When you apply the brakes, brake fluid is forced, under pressure, into the
wheel cylinder which, in turn, pushes the brake shoes into contact with the
machined surface on the inside of the drum. When the pressure is released,
return springs pull the shoes back to their rest position. As the brake linings
wear, the shoes must travel a greater distance to reach the drum. When the
distance reaches a certain point, a self-adjusting mechanism automatically
reacts by adjusting the rest position of the shoes so that they are closer to the
drum.
1.2.1 BRAKE SHOES
Like the disc pads, brake shoes consist of a steel shoe with the friction
material or lining riveted or bonded to it. Also like disc pads, the linings
eventually wear out and must be replaced. If the linings are allowed to wear
through to the bare metal shoe, they will cause severe damage to the brake
drum.
1.2.2 BACKING PLATE
The backing plate is what holds everything together. It attaches to the
axle and forms a solid surface for the wheel cylinder, brake shoes and
assorted hardware. It rarely causes any problems.
1.2.3 BRAKE DRUM
Brake drums are made of iron and have a machined surface on the
inside where the shoes make contact. Just as with disc rotors, brake drums
will show signs of wear as the brake linings seat themselves against the
machined surface of the drum. When new shoes are installed, the brake
drum should be machined smooth. Brake drums have a maximum diameter
specification that is stamped on the outside of the drum. When a drum is
machined, it must never exceed that measurement. If the surface cannot be
machined within that limit, the drum must be replaced.
1.2.4 WHEEL CYLINDER
The wheel cylinder consists of a cylinder that has two pistons, one on
each side. Each piston has a rubber seal and a shaft that connects the piston
with a brake shoe. When brake pressure is applied, the pistons are forced out
pushing the shoes into contact with the drum. Wheel cylinders must be
rebuilt or replaced if they show signs of leaking.
The major components of the drum brake assembly is shown in the
following figure the detailed exploded view of drum brake components.
1.2.5 RETURN SPRINGS
Return springs pull the brake shoes back to their rest position after the
pressure is released from the wheel cylinder. If the spring are weak and do
not return the shoes all the way, it will cause premature lining wear because
the linings will remain in contact with the drum. A good technician will
examine the springs during a brake job and recommend their replacement if
they show signs of fatigue. On certain vehicles, the technician may
recommend replacing them even if they look good as inexpensive insurance.
1.2.6 SELF ADJUSTING SYSTEM
The parts of a self adjusting system should be clean and move freely
to insure that the brakes maintain their adjustment over the life of the
linings. If the self adjusters stop working, you will notice that you will have
to step down further and further on the brake pedal before you feel the
brakes begin to engage. Disc brakes are self adjusting by nature and do not
require any type of mechanism. When a technician performs a brake job,
aside from checking the return springs, he will also clean and lubricates the
self adjusting parts where necessary.
1.3 PARKING BREAKS
The parking brake (a.k.a. emergency brake) system controls the rear
brakes through a series of steel cables that are connected to either a hand
lever or a foot pedal. The idea is that the system is fully mechanical and
completely by passes the hydraulic system so that the vehicle can be brought
to a stop even if there is a total brake failure.
In drum brakes, the cable pulls on a lever mounted in the rear brake
and is directly connected to the brake shoes. This has the effect of by passing
the wheel cylinder and controlling the brakes directly.
1. Support plate
2. Park brake shoes
3. Equalizer
4. Springs
5. Hold down clips
6. Adjuster
Disc brakes on the rear wheels add additional complication for parking
brake systems. There are two main designs for adding a mechanical parking
brake to rear disc brakes. The first type uses the existing rear wheel caliper
and adds a lever attached to a mechanical corkscrew device inside the
caliper piston. When the parking brake cable pulls on the lever, this
corkscrew device pushes the piston against the pads, thereby bypassing the
hydraulic system, to stop the vehicle. This type of system is primarily used
with single piston floating calipers, if the caliper is of the four piston fixed
type, then that type of system can’t be used. The other system uses a
complete mechanical drum brake unit mounted inside the rear rotor. The
brake shoes on this system are connected to a lever that is pulled by the
parking brake cable to activate the brakes. The brake “drum” is actually the
inside part of the rear brake rotor.
On cars with automatic transmissions, the parking brake is rarely used.
This can cause a couple of problems. The biggest problem is that the brake
cables tend to get corroded and eventually size up causing the parking brake
to become inoperative. By using the parking brake from time to time, the
cables stay clean and functional. Another problem comes from the fact that
the self adjusting mechanism on certain brake systems uses the parking
brake actuation to adjust the brakes. If the parking brake is never used, then
the brakes never get adjusted.
1.4 DISC BRAKES
1.4.1 INTRODUCTION
Disc brakes consist of a metal disc attached to the wheel hub that
rotates with the wheel. Calipers are attached to the frame or fork along with
pads that squeeze together on the disc. Such brakes have been successfully
used on motorcycles for decades, and been the principal choice there. The
disc brake is a lot like the brakes on bicycle. Bicycle brakes have a caliper,
which squeezes the brake pads against the wheel. In a disc brake, the brake
pads squeeze the rotor instead of the wheel, and the force is transmitted
hydraulically instead of through a cable. Friction between the pads and the
disc slows the disc down.
1.4.2 CONSTRUCTION
THEORY OF CONVENTIONAL HYDRAULIC DISC BRAKE
A Disc brake uses a flat, round disc or rotor, attached to the
wheel hub instead of a drum. Brake pads are positioned on the opposite sides
of the rotor and are mounted in the brake caliper. The caliper contains the
hydraulic piston used to apply the shoes and to transmit the braking forces
from the shoes to the suspension members.
All disc brakes are non energized, non servo brakes; lining pressure is
directly proportional to brake pedal pressure.
Centrifugal force will throw the contaminants off the rotor. A disc brake will
have much cooler operation than drum brakes because of increased area that
is exposed to the air flowing past it.
All modern automotive brake system uses a hydraulic system to
transmit the application forces from the brake pedal to the brake shoes.
The brake’s hydraulic system begins at the master cylinder. The
master cylinder is basically a piston type hydraulic pump operated by the
brake pedal. As brake pedal is pushed, brake fluid is pumped to the caliper
or wheel cylinder piston. This fluid pushes on the pistons, which push the
brake shoes against the rotor.
1.4.3 ADVANTAGES OF DISC BRAKES OVER DRUM BRAKES
In case of disc brakes the frictions surface is directly exposed to the
cooling air, so the heat dissipation is much easier in disc brake than
drum brakes.
The frictional surface in case of disc brakes are flat when compared to
curved surface of drum brakes, this mean in disc brakes there is
uniform wear.
Frictional pad material is not subjected to any bending, thereby
increasing the range of materials from which to choose the suitable
one.
The design of disc brakes is such that there is no loss efficiency due to
expansion, as the system becomes hot, expansion of drum of
internally expanded shoe types if brake tends to move the friction
surface apart, causing a loss of effective pedal travel, on the friction
surfaces slightly without tending to increase the clearance.
Disc brake weigh less than their conventional drum type counterpart a
saving approximately 20% being possible.
Disc brake has a better anti fade characteristics than drum brakes.
1.4. DISADVANTAGES
Any leakages of hydraulic fluid leads to brake failure
Air bubbles if any got trapped in the hydraulic circuit will result is
brake failure.
Sufficient level of brake fluid should always be maintained all the
time
Hydraulic disc brakes usually require relatively specialized tools to
bleed the brake systems.
Repairs on the trail are difficult to perform, whereas mechanical disc
brakes rarely fail completely.
Considering the above mentioned advantages and superior nature of disc
brakes we decided to choose modifications in disc brakes to make it much
simpler and more effective and cheaper design.
1.5 HYDRAULIC VS MECHANICAL
Two main disc brake systems exist: hydraulic and mechanical (cable-
actuated). Mechanical disc brakes (which are almost always less expensive
than hydraulic) have less modulation than hydraulic disc brake systems, and
since the cable is usually open to the outside, mechanical disc brake tend to
pick up small bits of dirt and grit in the cable lines when ridden in harsh
terrain. Hydraulic disc rakes use fluid from a reservoir, pushed through a
hose, to actuate the pistons in the disc caliper that then actuate the pads.
Hydraulic disc brake systems generally keep contaminants out better.
However, since hydraulic disc brakes usually require relatively specialized
tools to bleed the brake systems, repairs on the trail are difficult to perform,
whereas mechanical disc brakes rarely fail completely. Hydraulic disc
brakes occasionally require bleeding of the brake lines to remove air
bubbles. There are two types of brake fluid used in disc brakes today:
mineral oil and DOT fluid. Mineral oil is generally inert and while DOT has
a higher boiling point, it is known to be corrosive to frame paint. The two
are generally not interchangeable, as the different fluids may cause seals to
swell or be corroded. Also, the hydraulic fluid may boil on steep, continuous
down hills. This is due to heat building up in the disc and pads and can cause
the brake to lose its ability to transmit force through incompressible fluids,
since some of it has become a gas, which is compressible. To avoid this
problem, 203 mm (8 inch) diameter disc rotors have become common on
downhill bikes. Larges rotors dissipate heat more quickly and have a larger
amount of mass to absorb heat. For these reasons, one must weigh the
advantages and disadvantages of using a hydraulic system versus a
mechanical system.
POWER SUPPLY 5V DC AND 12V DC;
A 12 –0 v step down transformer is used to step-down 230V AC to
12V AC .This 12V AC supply is converted to 12V DC using four rectifier
diodes. The voltage from the rectifier section is regulated to 12V DC using
7812 IC .This voltage is used for supply for the DC motor. From 12V DC
the 7805 IC is used for regulating 5V DC for the power supply of
microcontroller. The power supply circuit is shown in fig.
POWER SUPPLY UNIT
INTRODUCTION:
All the electronic components starting from diode to Intel IC’s only
work with a DC supply ranging from +5V to +12V. We are utilizing for the
same, the cheapest and commonly available energy source of 230V-50Hz
and stepping down, rectifying, filtering and regulating the voltage.
STEP DOWN TRANSFORMER:
When AC is applied to the primary winding of the power transformer,
it can either be stepped down or stepped up depending on the value of DC
needed. In our circuit the transformer of 230V/15-0-15V is used to perform
the step down operation where a 230V AC appears as 15V AC across the
secondary winding. Apart from stepping down voltages, it gives isolation
between the power source and power supply circuitries.
RECTIFIER UNIT:
In the power supply unit, rectification is normally achieved using a
solid state diode. Diode has the property that will let the electron flow easily
in one direction at proper biasing condition. As AC is applied to the diode,
electrons only flow when the anode and cathode is negative. Reversing the
polarity of voltage will not permit electron flow. A commonly used circuit
for supplying large amounts of DCpower is the bridge rectifier. A bridge
rectifier of four diodes (4 x IN4007) are used to achieve full wave
rectification. Two diodes will conduct during the negative cycle and the
other two will conduct during the positive half cycle, and only one diode
conducts. At the same time one of the other two diodes conducts for the
negative voltage that is applied from the bottom winding due to the forward
bias for that diode. In this circuit due to positive half cycle D1 & D2 will
conduct to give 0.8V pulsating DC. The DC output has a ripple frequency
of 100Hz. Since each alteration produces a resulting output pulse, frequency
= 2 x 50 Hz. The output obtained is not a pure DC and therefore filtration
has to be done.
The DC voltage appearing across the output terminals of the bridge
rectifier will be somewhat less than 90% of the applied rms value. Normally
one alteration of the input voltage will reverse the polarities. Opposite ends
of the transformer will therefore always be 180 degree out of phase with
each other. For a positive cycle, two diodes are connected to the positive
voltage at the top winding.
FILTERING CIRCUIT:
Filter circuits which is usually capacitor acting as a surge arrester
always follow the rectifier unit. This capacitor is also called as a decoupling
capacitor or a bypassing capacitor, is used not only to ‘short’ the ripple with
frequency of 120Hz to ground but also to leave the frequency of the DC to
appear at the output. A load resistor R1 is connected so that a reference to
the ground is maintained. C1, R1 is for bypassing ripples. C2, R2 is used as
a low pass filter, i.e. it passes only low frequency signals and bypasses high
frequency signals. The load resistor should be 1% to 2.5% of the load.
1000f/25V : for the reduction of ripples from the pulsating
10f/25V : for maintaining the stability of the voltage at the load side.
0.1f : for bypassing the high frequency disturbances
FINISHING AND PAINTING
FINISHING AND PAINTING
JOB PREPARATION:
Before welding, remove any bend in the L angle with the sludge hammer on
the anvil block. Then it is cut to the required length with the hacksaw blade
and fabricated to required dimensional shape with arc welding.
FINISHING OPERATION BEFORE PAINTING:
After welding, any slag on the welded area is removed with the chipping
hammer and cleaned with the metal wire brush. Then all the surfaces are
rubbed with the emery sheet.
Metal primer is applied on the surfaces with the brush. After drying the
metal primer, the second coating is applied with the paint.
CONCLUSION
CONCLUSION
We make this project entirely different from other projects. Since
concepts involved in our project is entirely different that a single unit is used
to various purpose which is not developed by any of other team members.
We have successfully complete this project work at our Institute.
By doing this project work we understood the working principle of
uses of various Brakes, switches, control systems.
Once again we express our sincere thanks to our staff members.
COST ESTIMATION
COST ESTIMATION
1. Electromagnetic coil unit --------- 2100.00
2. brake unit with wheel -------- 1600.00
3. M.s. fabricated stand -------------- 600.00
4. DC power supply 12VDC -------------------------- 900.00
5. Wires, Screws and switch------ 300.00
6. Miscellaneous charges ----------------------------- 200.00------------------- 5900.00
BIBLIOGRAPHY
BIBLIOGRAPHY
“Automotive Braking System” , by Thomas W. birch.
“Automotive Engineering Fundamentals” by Richard Stone,
Jeffrey K. Ball
www.google.com
Automobile engineering ----g.b.s. narang
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