Fyp electromagnetic-brakes

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A

PROJECT REPORT ON

“ELECTROMAGNETIC BRAKE”

Submitted in partial fulfillment of the award

BACHELOR OF TECHNOLOGY

In

(Mechanical Engineering)

Session 2012-13

Submitted By:

AJAY YADAV (0935740003)

Under the Guidance

Of

Mr. SANDEEP SINGH

(Lecturer, M.E Department)

Aryavart Institute Of Technology & Management , Lucknow

Affilated To

Gautam Budha Technical University, Lucknow

http://www.final-yearproject.com/


CERTIFICATE

This is to certify that Project synopsis entitled “ELECTROMAGNETIC BRAKE” which is submitted by AJAY YADAV in partial fulfillment of requirement for the award of degree Bachelor Of Technology in MECHANICAL ENGINEERING from ARYAVART INSTITUTE OF TECHNOLOGY & MANAGEMENT , LUCKNOW (G.B.T.U) is a record of the candidate own work carried out by her under my supervision . The matter embodied in this project is original and has not been submitted

for the award of any other degree.

Under the Guidance of: Submitted To:

Mr. SANDEEP SINGH Mr. PRINCE SRIVASTAVA (Lecturer, ME Department) H.O.D (ME Department)

Mr. SIMANT SRIVASTAVA

(DEAN)

(ME Department)

Date :

Place:



ACKNOWLEDGEMENT

One of the parts of preparing this project is to thanks those who have helped me through their valuable participation , comments and suggestion . We wish to thank’s , ARYAVART INSTITUTE OF TECHNOLOGY & MANAGEMENT , LUCKNOW whose co-operation and attitude toward encouraging a student is appreciable . We sincerely express our gratitude to the project guide Mr. Sandeep Singh (Lecturer, ME Department) for his guidance in completing the project titled ‘electromagnetic brake’ . Without his guidance this project would not have been completed , her kindness and help have been the source of encouragement for us thoughout the project.

We would like to thanks our project coordinator Mr. prince srivastava for all his support and help in collecting information about ‘ELECTROMAGNETIC BRAKE’ , implementing the same in the project and using it successfully. Last but not the least , we express our deep gratitude to our academic dean Mr. Simant Srivastava for contribution of his ideas for our project . We would also like to pay our regard to the whole M.E department for their support and guidance .

Finally a lot of thanks to our friends and family member , who helped and motivation us to develop such a wonderful solution.

(AJAY YADAV)



TABLE OF CONTENTS

• INTRODUCTION

• GENERAL PRINCIPLE OF BRAKE SYSTEM

• Conventional Friction Brake

• How ordinary (friction) brakes work

• “Brake Fading” Effect

• Retarders

• Construction

• General Principle and Advantage of Electromagnetic Brakes (retarders)

• Working Principle

• Electric Control System

• TYPES OF ELECTROMAGNETIC BRAKE

• Characteristic of Electromagnetic Brakes

• Thermal Dynamics



• MERITS

• DERMIRTS

• APPLICATION

• Summary

1. Introduction

Electromagnetic brakes have been used as supplementary retardation

equipment in addition to the regular friction brakes on heavy vehicles. We

outline the general principles of regular brakes and several alternative

retardation techniques in this section. The working principle and characteristics

of electromagnetic brakes are then highlighted. In this project we are trying to

make a braking system. which can be applicable in two wheeler at high speed

and low maintenance cost. Here we are using an electromagnetic coil and a

plunger. There is an electromagnetic effect which moves the plunger in the

braking direction.

When electricity is applied to the field, it creates an

internal magnetic flux. That flux is then transferred into a hysteresis disk



passing through the field. The hysteresis disk is attached to the brake shaft. A

magnetic drag on the hysteresis disk allows for a constant drag, or eventual

stoppage of the output shaft.

Electromagnetic brakes (also called electro-mechanical

brakes or EM brakes) slow or stop motion using electromagnetic force to apply

mechanical resistance (friction). The original name was "electro-mechanical

brakes" but over the years the name changed to "electromagnetic brakes",

referring to their actuation method. Since becoming popular in the mid-20th

century especially in trains and trolleys, the variety of applications and brake

designs has increased dramatically, but the basic operation remains the same.

Both electromagnetic brakes and eddy current brakes use electromagnetic force

but electromagnetic brakes ultimately depend on friction and eddy current

brakes use magnetic force directly.

Materials

36 Gauge Magnet wire ,

AC Motor ,

Sprint ,

Iron Stand,

Wheel

Description:

http://en.wikipedia.org/wiki/Electromagnetism


http://en.wikipedia.org/wiki/Eddy_current_brake

http://en.wikipedia.org/wiki/Brake


The disc brake or disk brake is a device for slowing or stopping the rotation of a

wheel. A brake disc usually made of cast iron or ceramic composites is

connected to the wheel and the axle. To stop the wheel, friction material in the

form of brake pads is forced mechanically, hydraulically, pneumatically or

electromagnetically against both sides of the disc. Friction causes the disc and

attached wheel to slow or stop. But in our project hydraulic energy is used as

the source of power, due to high applied force and torque

2. General Principle of Brake System

The principle of braking in road vehicles involves the conversion of kinetic

energy into thermal energy (heat). When stepping on the brakes, the driver

commands a stopping force several times as powerful as the force that puts the

car in motion and dissipates the associated kinetic energy as heat. Brakes must

be able to arrest the speed of a vehicle in a short periods of time regardless

how fast the speed is. As a result, the brakes are required to have the ability to

generating high torque and absorbing energy at extremely high rates for short

periods of time. Brakes may be applied for a prolonged periods of time in some

applications such as a heavy vehicle descending a long gradient at high speed.

Brakes have to have the mechanism to keep the heat absorption capability for

prolonged periods of time.

3. Conventional Friction Brake

The conventional friction brake system is composed of the following basic

components: the “master cylinder” which is located under the hood is directly



connected to the brake pedal, and converts the drivers’ foot pressure into

hydraulic pressure. Steel “brake hoses” connect the master cylinder to the

“slave cylinders” located at each wheel. Brake fluid, specially designed to work

in extreme temperature conditions, fills the system. “Shoes” or “pads” are

pushed by the slave cylinders to contact the “drums” or “rotors,” thus causing

drag, which slows the car. Two major kinds of friction brakes are disc brakes

and drum brakes. Disc brakes use a clamping action to produce friction between

the “rotor” and the “pads” mount in the “caliper” attached to the suspension

members Disc brakes work using the same basic principle as the brakes on a

bicycle: as the caliper pinches the wheel with pads on both sides, it slows the

vehicle.

Drum brakes consist of a heavy flat-topped cylinder, which is

sandwiched between the wheel rim and the wheel hub . The inside surface of

the drum is acted upon by the linings of the brake shoes. When the brakes are

applied, the brake shoes are forced into contact with the inside surface of the

brake drum to slow the rotation of the wheels.

Air brakes use standard hydraulic brake system components such as

braking lines, wheel cylinders and a slave cylinder similar to a master cylinder

to transmit the air-pressure-produced braking energy to the wheel brakes. Air

brakes are used frequently when greater braking capacity is required.

4-How ordinary (friction) brakes work

Moving things have kinetic energy and, if you want to stop them, you have to

get rid of that energy somehow. If you're on a bicycle going fairly slowly, you

can simply put your feet down so they drag on the ground. The soles of your


http://www.explainthatstuff.com/energy.html


feet act as brakes. Friction (rubbing) between the rough ground and the grip on

your soles slows you down, converting your kinetic energy into heat energy (do

it long enough and your shoes will get hot). Brakes on vehicles work pretty

much the same way, with "shoes" that press rubber pads (brake blocks) against

discs mounted to the wheels. (Find out more about this in our main article on

brakes.) Even if you make brakes from super-strong, hard-wearing materials

like Kevlar®, they're still going to wear out sooner or later. But there are other

problems with friction brakes. The faster you go, the harder they have to work

to get rid of your kinetic energy, and the quicker they'll wear out. Use your

brakes too often and you may suffer a problem called brake fade, where heat

builds up too much in the brakes or the hydraulic system that operates them

and the brakes can no longer work as effectively. What if your brakes can't stop

you in time?

In Motorcycle brakes , When you pull on the brake handle, a

hydraulic cable applies the brake pads to the brake rotor disc, slowing the

machine down by converting your kinetic energy to heat. The tire doesn't

normally play much part in braking unless you brake really hard: then the wheel

will lock completely and friction between the tire and the road will bring you to a

sudden halt, leaving a rubber skid mark on the road. That's not a good way to

brake: it'll wear out your tires very quickly.

5. “Brake Fading” Effect

The conventional friction brake can absorb and convert enormous energy values

(25h.p. without self-destruction for an 5-axle truck, Reverdin1974), but only if

http://www.explainthatstuff.com/hydraulics.html

http://www.explainthatstuff.com/kevlar.html

http://www.explainthatstuff.com/brakes.html

http://www.explainthatstuff.com/howwheelswork.html

http://www.explainthatstuff.com/rubber.html

http://www.explainthatstuff.com/energy.html


the temperature rise of the friction contact materials is controlled. This high

energy conversion therefore demands an appropriate rate of heat dissipation if

a reasonable temperature and performance stability are to be maintained.

Unfortunately, design, construction, and location features all severely limit the

heat dissipation function of the friction brake to short and intermittent periods

of application. This could lead to a ‘brake fade’ problem (reduction of the

coefficient of friction, less friction force generated) due to the high temperature

caused by heavy brake demands. The main reasons why conventional friction

brakes fail to dissipate heat rapidly are as follows:

- poor ventilation due to encapsulation in the road wheels,

- diameter restriction due to tire dimensions,

- width restrictions imposed by the vehicle spring designer;

- problems of drum distortion at widely varying temperatures.

It is common for friction-brake drums to exceed 500 °C surface temperatures

when subject to heavy braking demands, and at temperatures of this order, a

reduction in the coefficient of friction (‘brake fade’) suddenly occurs. The

potential hazard of tire deterioration and bursts is perhaps also serious due to

the close proximity of overheated brake drums to the inner diameter of the tire.

5. Retarders

Retarders are means of of overcoming the above problems by augmenting a

vehicle’s foundation brakes with a device capable of opposing vehicle motion at

relatively low levels of power dissipation for long periods. There are several

retarder technologies currently available. Two major kinds are the hydrokinetic

brake and the exhaust brake. Hydrokinetic brake uses fluid as the working

medium to oppose rotary motion and absorb energy . Hydrodynamic brakes are


often built into hydrodynamic transmissions . Exhaust brakes use a valve which

is fitted into the exhaust pipe between the exhaust manifold and silencer. When

this valve is closed air is compressed against it through the open exhaust valve

by the piston rising on the exhaust stroke. In that way the engine becomes a

low pressure single stage compressor driven by the vehicle’s momentum,

resulting in a retarding effect being transmitted through the transmission to the

driving road wheels. The power-producing engine is converted into a power

absorbing air compressor . This approach could put a lot of stress on the

cylinder and exhaust system. So it may require extra engineering efforts to

implement this system. As a brake applied to the engine, exhaust brakes can

only absorb as much power as the engine can deliver. But the power absorbed

in braking is usually greater than the power absorbed in driving. Compared with

these retarders, electromagnetic brakes have greater power capability,

simplicity of installation and controllability.

6-construction-

The construction of the electromagnetic braking system is very simple. The

parts needed for the construction are electro magnets, rheostat, sensors and

magnetic insulator. A cylindrical ring shaped electro magnet with winding is

placed parallel to rotating wheel disc/ rotor. The electro magnet is fixed, like as

stator and coils are wounded along the electromagnet. These coils are

connected with electrical circuit containing one rheostat which is connected

with brake pedal. And the rheostat is used to control the electric current flowing

in the coils which are wounded on the electro magnet and a magnetic insulator

is used to focus and control the magnetic flux. And also it is used to prevent the

magnetisation of other parts like axle and it act as a support frame for the

electromagnet. The sensors used to indicate the disconnection in the whole


circuit. If there is any error it gives an alert, so we can avoid accident. Working

principle : At the initial stage the brake pedal and rheostat are in rest. When we

apply the brake through the brake pedal, the rheostat allows the current to flow

through the circuit and this current energise the electromagnet. The amount of

current flow is controlled by the rheostat. Depending on the current flow

different amount of magnetic flux can be obtained. By this varying magnetic

flux, different mode of brakes can be obtained. For example, if we want to

suddenly stop the vehicle then press the brake pedal fully, then the rheostat

allos maximum current which is enough to stop the vehicle. Similarly we can

reduce the speed of the vehicle by applying the brake gradually.


7. General Principle and Advantage of Electromagnetic Brakes

(retarders)

Installation Location

Electromagnetic brakes work in a relatively cool condition and satisfy all the

energy requirements of braking at high speeds, completely without the use of

friction. Due to its specific installation location (transmission line of rigid

vehicles), electro magnetic brakes have better heat dissipation capability to

avoid problems that friction brakes face as we mentioned before. Typically,

electromagnetic brakes have been mounted in the transmission line of vehicles,


The propeller shaft is divided and fitted with a sliding universal joint and is

connected to the coupling flange on the brake. The brake is fitted into the

chassis of the vehicle by means of anti-vibration mounting. The practical

location of the retarder within the vehicle prevents the direct impingement of air

on the retarder caused by the motion of the vehicle. Any air flow movement

within the chassis of the vehicle is found to have a relatively insignificant effect

on the air flow around tire areas and hence on the temperature of both front

and rear discs. So the application of the retarder does not affect the

temperature of the regular brakes. In that way, the retarders help to extend the

life span of the regular brakes and keep the regular brakes cool for emergency

situation. Electromagnetic brakes work in a relatively cool condition and satisfy

all

the energy requirements of braking at high speeds, completely without the use

of friction. Due to its specific installation location (transmission line of rigid

vehicles).

There are in existence several types of electromagnetic retarder. In

particular, there are electromagnetic retarders of the axial type and

electromagnetic retarders of the Focal type. An electromagnetic retarder of the

axial type is designed to be placed on a transmission shaft between a rear

axle and a gearbox of the vehicle. In that case, the transmission shaft is in two

parts, for mounting between those of the retarder. An electromagnetic retarder

of the Focal type is designed to be placed directly on a transmission shaft on the

output side of the gearbox or on the axle of the vehicle. The axle of a vehicle

drives at least one road wheel, which road wheel drives at least one wheel of

the same vehicle.

8. Working Principle-


The working principle of the electric retarder is based on the creation of eddy

currents within a metal disc rotating between two electromagnets, which sets

up a force opposing the rotation of the disc . If the electromagnet is not

energized, the rotation of the disc is free and accelerates uniformly under the

action of the weight to which its shaft is connected. When the electromagnet is

energized, the rotation of the disc is retarded and the energy absorbed appears

as heating of the disc. If the current exciting the electromagnet is varied by a

rheostat, the braking torque varies in direct proportion to the value of the

current. It was the Frenchman Raoul Sarazin who made the first vehicle

application of eddy current brakes. The development of this invention began

when the French company Telma, associated with Raoul

Sarazin, developed and marketed several generations of electric brakes based

on the functioning principles described above . A typical retarder consists of

stator and rotor. The stator holds 16 induction coils, energized separately in

groups of four. The coils are made up of varnished aluminum wire mounded in

epoxy resin. . The rotor is made up of two discs, which provide the braking

force. when subject to the electromagnetic influence when the coils are excited.

Careful design of the fins, which are integral to the disc, permit independent

cooling of the arrangement.


9. Electric Control System

The energization of the retarder is operated by a hand control mounted on the

steering column of the vehicle. This control has five positions: the first is ‘off’,

and the four remaining positions increase the braking power in sequence. This

hand-control system can be replaced by an automatic type that can operate

mechanically through the brake pedal. In this case, the contacts are switched

on successively over the slack movement of the brake pedal. The use of an

automatic control must be coupled with a cut-off system operating at very low

vehicle speed in order to prevent energization of the retarder while the vehicle

is stationary with the driver maintaining pressure on the brake pedal. Both the

manual control and the automatic control activate four solenoid contractors in


the relay box, which in turn close the four groups of coil circuits within the

electric brake at either 24 volts or 12 volts, as appropriate (Reverdin 1974 and

Omega Technologies).

10-TYPES OF ELECTROMAGNETIC BRAKE

(1)-Single Disc Electromagnetic Brakes-

Features:-

• Brake is used to Brake and maintain the rotating body

• Designed for dry-operation

• Slim Brakes with good performance and can quickly stop loads

• Lightweight and easy to mount in any machinery


• We manufacture Single Disc Electromagnetic Brakes - Equivalents to

world leading manufacturers like:Intorq, Lenze, KEB, PSP, Miki-Pulley and

more

Technical Features:

• These can quickly stop loads

• Technical Features Torque: 3NM to 500NM

• Single Plate Dry Type

• High Operating Reliability / frequency

• Simple Construction

• Unique pre-stressed spring

• Raw material to DIN standards

• Special friction material

• Can be used in mounting positions

• Different armature designs are available for different applications

• Different voltages options are also available on request.


(2)-Multi-Disc Electromagnetic Brakes -Brake with magnet body front face

fastened to housing For oil operation.

Equivalents to ZF Brakes - EK 1B, EK 2DB, EK 5DB, EK 10EB, EK 20DB, EK

20EB, EK 40DB, EK 40EB, EK 60DB, EK 80B, EK 120EB, EK 160B, EK 320B.

Technical Features:

• Coil Voltage: 24 V

• Torque: 3 N-m to 3600 N-m

• Compact design

• Electromagnetic brakes are provided

• With or without outer carrier, jaw and driver


• With inner & outer multiple discs.

(3)Single face brake

Main article: Friction-plate electromagnetic couplings

http://en.wikipedia.org/wiki/Friction-plate_electromagnetic_couplings

http://en.wikipedia.org/wiki/File:A-3_electromagnetic-brake1.gif


A friction-plate brake uses a single plate friction surface to engage the input

and output members of the clutch. Single face electromagnetic brakes make

up approximately 80% of all of the power applied brake applications.

(4)Power off brake

Electormagnetic Power Off Brake Spring Set

Power off brakes stop or hold a load when electrical power is either

accidentally lost or intentionally disconnected. In the past, some companies

have referred to these as "fail safe" brakes. These brakes are typically used

on or near an electric motor. Typical applications include robotics, holding

brakes for Z axis ball screws and servo motor brakes. Brakes are available

in multiple voltages and can have either standard backlash or zero backlash

hubs. Multiple disks can also be used to increase brake torque, without

http://en.wikipedia.org/wiki/File:O-2_electromagnetic-power-off-brake1.gif

http://en.wikipedia.org/wiki/File:O-2_electromagnetic-power-off-brake1.gif


increasing brake diameter. There are 2 main types of holding brakes. The

first is spring applied brakes. The second is permanent magnet brakes.

(a) Spring type - When no electricity is applied to the brake, a spring

pushes against a pressure plate, squeezing the friction disk between the

inner pressure plate and the outer cover plate. This frictional clamping force

is transferred to the hub, which is mounted to a shaft.

(b)Permanent magnet type – A permanent magnet holding brake looks

very similar to a standard power applied electromagnetic brake. Instead of

squeezing a friction disk, via springs, it uses permanent magnets to attract a

single face armature. When the brake is engaged, the permanent magnets

create magnetic lines of flux, which can turn attract the armature to the

brake housing. To disengage the brake, power is applied to the coil which

sets up an alternate magnetic field that cancels out the magnetic flux of the

permanent magnets.

Both power off brakes are considered to be engaged when no power is

applied to them. They are typically required to hold or to stop alone in the

event of a loss of power or when power is not available in a machine

circuit. Permanent magnet brakes have a very high torque for their size, but

also require a constant current control to offset the permanent magnetic

field. Spring applied brakes do not require a constant current control, they


can use a simple rectifier, but are larger in diameter or would need stacked

friction disks to increase the torque.

(5)Particle brake

Magnetic Particle Brake

Magnetic particle brakes are unique in their design from other electro-

mechanical brakes because of the wide operating torque range available.

Like an electro-mechanical brake, torque to voltage is almost linear;

however, in a magnetic particle brake, torque can be controlled very

accurately (within the operating RPM range of the unit). This makes these

units ideally suited for tension control applications, such as wire winding,

foil, film, and tape tension control. Because of their fast response, they can

http://en.wikipedia.org/wiki/File:Electromagnetic_Particle_Brake.gif


also be used in high cycle applications, such as magnetic card readers,

sorting machines and labeling equipment.

Magnetic particles (very similar to iron filings) are located in the powder

cavity. When electricity is applied to the coil, the resulting magnetic flux

tries to bind the particles together, almost like a magnetic particle slush. As

the electric current is increased, the binding of the particles becomes

stronger. The brake rotor passes through these bound particles. The output

of the housing is rigidly attached to some portion of the machine. As the

particles start to bind together, a resistant force is created on the rotor,

slowing, and eventually stopping the output shaft.

When electricity is removed from the brake, the input is free to turn with

the shaft. Since magnetic particle powder is in the cavity, all magnetic

particle units have some type of minimum drag associated with them.

(6)Hysteresis power brake

http://en.wikipedia.org/wiki/File:Electromagnetic_Hysteresis_Power_Brake.gif


Electomagnetic Hysteresis Power Brake

Electrical hysteresis units have an extremely wide torque range. Since these

units can be controlled remotely, they are ideal for test stand applications

where varying torque is required. Since drag torque is minimal, these units

offer the widest available torque range of any of the hysteresis products.

Most applications involving powered hysteresis units are in test stand

requirements.

When electricity is applied to the field, it creates an internal magnetic flux.

That flux is then transferred into a hysteresis disk passing through the field.

The hysteresis disk is attached to the brake shaft. A magnetic drag on the

hysteresis disk allows for a constant drag, or eventual stoppage of the

output shaft.

When electricity is removed from the brake, the hysteresis disk is free to

turn, and no relative force is transmitted between either member. Therefore,

the only torque seen between the input and the output is bearing drag.

(7)Multiple disk brake


Electromagnetic Multiple Disk Brake

Multiple disk brakes are used to deliver extremely high torque within a

small space. These brakes can be used either wet or dry, which makes them

ideal to run in multi-speed gear box applications, machine tool applications,

or in off road equipment.

Electro-mechanical disk brakes operate via electrical actuation, but transmit

torque mechanically. When electricity is applied to the coil of an

electromagnet, the magnetic flux attracts the armature to the face of the

brake. As it does so, it squeezes the inner and outer friction disks together.

The hub is normally mounted on the shaft that is rotating. The brake

housing is mounted solidly to the machine frame. As the disks are

http://en.wikipedia.org/wiki/File:Multiple-disk-electromagnetic-brake1.gif

http://en.wikipedia.org/wiki/File:Multiple-disk-electromagnetic-brake1.gif


squeezed, torque is transmitted from the hub into the machine frame,

stopping and holding the shaft.

When electricity is removed from the brake, the armature is free to turn

with the shaft. Springs keep the friction disk and armature away from each

other. There is no contact between braking surfaces and minimal drag.

11-Characteristic of Electromagnetic Brakes-

It was found that electromagnetic brakes can develop a negative power

which represents nearly twice the maximum power output of a typical engine,

and at least three times the braking power of an exhaust brake . These

performance of electromagnetic brakes make them much more competitive

candidate for alternative retardation equipments compared with other retarders.

By using the electro-magnetic brake as supplementary10 retardation

equipment, the friction brakes can be used less frequently, and therefore

practically never reach high temperatures. The brake linings would last

considerably longer before requiring maintenance, and the potentially “brake

fade” problem could be avoided. In research conducted by a truck

manufacturer, it was proved that the electromagnetic brake assumed 80

percent of the duty which would otherwise have been demanded of the regular

service brake . Furthermore, the electromagnetic brake prevents the dangers

that can arise from the prolonged use of brakes beyond their capability to

dissipate heat. This is most likely to occur while a vehicle descending a long

gradient at high speed. In a study with a vehicle with 5 axles and weighing 40

tons powered by an engine of 310 b.h.p traveling down a gradient of 6 percent


at a steady speed between 35 and 40 m.p.h, it can be calculated that the

braking power necessary to maintain this speed is the order of 450 h.p. The

braking effect of the engine even with a fitted exhaust brake is approximately

150 h.p. The brakes, therefore, would have to absorb 300 h.p,

meaning that each brake in the 5 axles must absorb 30 h.p, which is beyond the

limit of 25 h.p. that a friction brake can normally absorb without self

destruction. The electromagnetic brake is well suited to such conditions since it

will independently absorb more than 300 h.p . It therefore can exceed the

requirements of continuous uninterrupted braking, leaving the friction brakes

cool and ready for emergency braking in total safety. The installation of an

electromagnetic brake is not very difficult if there is enough space between the

gearbox and the rear axle. It does not need a subsidiary cooling system. It does

not rely on the efficiency of engine components for its use, as do exhaust and

hydrokinetic brakes. The electromagnetic brake also has better controllability.

The exhaust brake is an on/off device and hydrokinetic brakes have very

complex control system. The electromagnetic brake control system is an

electric switching system which gives it superior controllability. 11 From the

foregoing, it is apparent that the electro-magnetic brake is an attractive

complement to the safe braking of heavy vehicles.

12-Thermal Dynamics-

Thermal stability of the electromagnetic brakes is achieved by means of the

convection and radiation of the heat energy at high temperature. The major

part of the heat energy is imparted to the ventilationg air which is circulating

vigorously through the fan of the heated disc. The value of the energy

dissipated by the fan can be calculated by the following expression:


Q MCp = ∆θ (2.1)

where:

M = Mass of air circulated;

Cp = Calorific value of air;

∆θ= Difference in temperature between the air entering and the air leaving the

fan;

The electromagnetic brakes has excellent heat dissipation efficiency owing to

the high temperature of the surface of the disc which is being cooled and also

because the flow of air through the centrifugal fan is very rapid. Therefore, the

curie temperature of the disc material could never been reached .The practical

location of the electromagnetic brakes prevents the direct impingement of air on

the brakes caused by the motion of the vehicle. Any air flow movement within

the chassis of the vehicle is found to have a relatively 12 insignificant effect on

the air flow and hence temperature of both front and rear discs. Due to its

special mounting location and heat dissipation mechanism, electromagnetic

brakes have better thermal dynamic performance than regular friction brakes.

13-MERITS-

Quick operation

Accuracy is more.

It reduces the manual effort.

In electromagnetic braking system maintenance is very less.


electromagnetic braking system work is done very fast, because of

electronic component. And flowing of current is very fast.

Very less effort is required to apply the brake.‡

It is reasonable as compare with other brakes.

14-DERMIRTS-

Cylinder stroke length is constant

Need a separate compressor

Maintenance of the equipment components such as hoses, valves

has to done periodically.

15-APPLICATION -

Used in crane control system

Used in winch controlling

Used in lift controlling Used in automobile purpose

In locomotives, a mechanical linkage transmits torque to an

electromagnetic braking component.

Trams and trains use electromagnetic track brakes where the braking

element is pressed by magnetic force to the rail. They are distinguished

from mechanical track brakes, where the braking element is mechanically

pressed on the rail.

Electric motors in industrial and robotic applications also employ

electromagnetic brakes.

http://en.wikipedia.org/wiki/Rail_tracks

http://en.wikipedia.org/wiki/Track_brake

http://en.wikipedia.org/wiki/Train

http://en.wikipedia.org/wiki/Tram

http://en.wikipedia.org/wiki/Torque


16- Summary

With all the advantages of electromagnetic brakes over friction brakes, they

have been widely used on heavy vehicles where the ‘brake fading’ problem is

serious. The same concept is being developed for application on lighter

vehicles.

Education

Fyp electromagnetic-brakes