Electro Magnetic Brake

8/2/2019 Electro Magnetic Brake

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ELECTRO -MAGNETIC BRAKES


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GROUP MEMBERS :

KSHITIJ K. WEER.GAYNOR GRATION

LEWIS .SANKET S. TAVSALKAR.

SANJEEV A. BAWASKAR.


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I ND E X

Summary

Introduction

Concept & product detail

Types of electromagneticbrake

Product detail

Product requirements Machinery required

Future scope

Conclusion

references

: SUMMARY :


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Now days, the lots of newtechnologies are arriving in world. Theycreate a lot of effect. Most of industriesgot their new faces due to this arrival oftechnologies. Automobile industry isalso one of them. There is a boom inworlds automobile industry, so lots ofresearch is also going here. As animportant part of automobile, there arealso innovations in brakes.Electromagnetic brakes is one of them.

Electromagnetic brakes is a newrevolutionary concept. Electromagneticbrakes are the brakes working onelectric power & magnetic power. Theyworks on the principle ofelectromagnetism. These are totallyfrictionless. Due to this, they are moredurable & have longer life span. Lessmaintenance is there. These brakes arean excellent replacement on theconventional brakes due to their manyadvantages. The reason forimplementing this brake in automobiles

is to reduce wear in brakes as it isfrictionless. Therefore there will also beno heat loss. It can be used in heavyvehicles as well as in light vehicles. Theelectromagnetic brakes are mucheffective than conventional brakes &the time taken for application of brakes

are also smaller. There is very few need


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of lubrication. Electromagnetic brakesgives better performance with less costwhich is todays need. There are also

many more advantages ofElectromagnetic brakes. Thats whyElectromagnetic brakes are an excellentreplacement on conventional brakes.Electromagnetic brakes are the need oftodays automobiles.

A electromagnetic braking systemfor automobiles like cars, an effectivebraking system. And, by using thiselectro magnetic brakes, we canincreases the life of the braking unit.The working principle of this system isthat when the magnetic flux passes

through and perpendicular to therotating wheel the eddy current isinduced in the rotating wheel or rotor.This eddy current flows opposite to therotating wheel/rotor direction. This eddycurrent trying to stop the rotating wheelor rotor. This results in the rotating

wheel or rotor comes to rest/ neutral.Construction :The construction of the electromagneticbraking system is very simple. The partsneeded for the construction are electromagnets, rheostat, sensors andmagnetic insulator. A cylindrical ringshaped electro magnet with winding isplaced parallel to rotating wheel disc/


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rotor. The electro magnet is fixed, likeas stator and coils are wounded alongthe electromagnet. These coils are

connected with electrical circuitcontaining one rheostat which isconnected with brake pedal. And therheostat is used to control the electriccurrent flowing in the coils which arewounded on the electro magnet and amagnetic insulator is used to focus and

control the magnetic flux. And also it isused to prevent the magnetisation ofother parts like axle and it act as asupport frame for the electromagnet.The sensors used to indicate thedisconnection in the whole circuit. Ifthere is any error it gives an alert, so

we can avoid accident.Working principle : At the initial stagethe brake pedal and rheostat are inrest. When we apply the brake throughthe brake pedal, the rheostat allows thecurrent to flow through the circuit andthis current energise the electromagnet.

The amount of current flow is controlledby the rheostat. Depending on thecurrent flow different amount ofmagnetic flux can be obtained. By thisvarying magnetic flux, different mode ofbrakes can be obtained. For example, ifwe want to suddenly stop the vehiclethen press the brake pedal fully, thenthe rheostat allows maximum current


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which is enough to stop the vehicle.Similarly we can reduce the speed ofthe vehicle by applying the brake

gradually.

: INTRODUCTION :

Currently the automobile safetynorms are going strict & strict which is

important for saving occupants life incase of emergency. Brakes are one ofthe safety systems in automobiles.These days, many types of brakes are inuse. Lets first see what are brakes.

Brake :

Brake is a device which inhibitsmotion or stops motion. They are theessential & important part of safetysystem of automobile. The primaryfunctions of brakes are as follows.

1. To stop the vehicle in minimum

possible distance.

2. To park the vehicle on slops.

For these purposes, brakes are used.Many developments are made in designof brakes. The brakes are classified as,

According to purpose :


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1) Primary or service brake.

2) Secondary or Parking brakes.

According to construction :

1)Drum Brake.

2) Disc Brake.

According to method of actuation :

1) Mechanical brake.

2) Hydraulic brake.

3) Air brake.

4) Electric brake.

5) Vacuum brake.

Brakes are generally applied torotating axles or wheels. Some vehiclesuse a combination of brakingmechanisms, such as drag racing carswith both wheel brakes and a

parachute, or airplanes with both wheelbrakes and drag flaps raised into the airduring landing. Let us see somecommonly used brakes in automobiles.

Drum Brake :

It uses the principle of Friction whichis caused by a set of shoes or friction


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pads that press against a rotating partknown as brakes. The modernautomobile drum brake was invented in

1902, though a less-sophisticated drumbrake had been used a year earlier.

It consists of a brake drum which isconcentric to the axle hub whereas onthe axle casing is mounted a back plate.The back plate is made up of pressedsteel sheet and it provides support forthe expander, anchor and brake shoes.It also protects the drum and shoe frommud and dust. Two brake shoes areanchored on the back plate, frictionlinings are mounted on brake shoe. Oneor more retractor springs are usedwhich serves to keep the brake shoeaway from the drum when the brake isnot applied the brake shoe is anchoredat one end whereas at other end force isapplied by some other actuatingmechanisms. When force is applied atone end of brake shoe it moves againstthe revolving drum thereby applying the

brakes.

These brakes has disadvantages likegreater wear & tear. Also heatdissipation is poor. Diameter restrictiondue to tire dimensions, widthrestrictions imposed by the vehicle

spring designer, problems of drum


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distortion at widely varyingtemperatures. These brakes are lesseffective than other types.


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DRUM BRAKES

Disc Brake :

Disc brakes work using the samebasic principle as the

brakes on a bicycle as the calliperpinches the wheel with pads on bothsides, it slows the vehicle.

Development of Disc-style brakesand use began in England in the 1890s.The first calliper-type automobile discbrake was patented by Fedrick William

Lanchester in his Birmingham factory in


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1902 and was used successfully onLanchester cars. It consist of a cast irondisc bolted to the wheel hub and a

stationary housing called calliper. Thecalliper is connected to the axial facingor stub axle and is cast in two parts.Each part contains a piston and inbetween each piston and the disc thereis a fricyion pad held in position byretaining pins and spring plates. There

are passages drilled in the calliper forfluid to enter or lead the housing. Thepassages are also connected to oneanother for bleeding. When the brakesare applied hydraulically actuatedpiston moves the friction pads incontact with the disc applying equal and

opposite force on the disc, on releasingthe brakes, the rubber sealing rings actas return spring and retract the pistonsand friction pads away from the disc.

These brakes are more costlier &effective than drum brakes.


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DISC BRAKE


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Air Brake :

Air brakes use standard hydraulicbrake system components such asbraking lines, wheel cylinders and aslave cylinder similar to a mastercylinder to transmit the air-pressure-

produced braking energy to the wheelbrakes. Air brakes are used frequentlywhen greater braking capacity isrequired.


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AIR BRAKE


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Hand Brake :

Hand brakes are the parking oremergency brakes. They helps a vehicleto park on a slope or duringemergencies when primary brakes aredisabled. They works independently ofprimary brakes.


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HAND BRAKE

Electromagnetic Brake :

Electromagnetic brakes operateelectrically, but transmit torquemechanically. This is why they are usedto be referred to as electro-mechanicalbrakes. Over the years, EM brakesbecame known as electromagnetic,referring to their actuation method.

There are three parts in anelectromagnetic brake: field, armatureand hub (which is the input on a brake).

Usually the magnetic field is bolted to


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the machine frame (or uses a torquearm that can handle the torque of thebrake). So when the armature is

attracted to the field the stoppingtorque is transferred into the fieldhousing and into the machine framedecelerating the load. This can happenvery fast (0.1-3sec).

`Disengagement is very simple.Once the field starts to degrade fluxfalls rapidly and the armatureseparates. A spring holds the armatureaway from its corresponding contactsurface at a predetermined air gap.


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ELECTROMAGNETIC BRAKE

: CONCEPT & PRODUCT DETAIL :

CONCEPT :

Voltage/Current - And the MagneticField

RIGHT HAND RULE
http://en.wikipedia.org/wiki/File:V-1_right_hand_thumb_rule.gif


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If a piece of copper wire was wound,around the nail and then connected to abattery, it would create an electro

magnet. The magnetic field that isgenerated in the wire, from the current,is known as the right hand thumbrule. (V-1) The strength of themagnetic field can be changed bychanging both wire size and the amountof wire (turns). EM clutches are similar;

they use a copper wire coil (sometimesaluminum) to create a magnetic field.

The fields of EM brakes can be madeto operate at almost any DC voltage andthe torque produced by the brake willbe the same as long as the correctoperating voltage and current is usedwith the correct brake. If a 90 volt brakehad 48 volts applied to it, this would getabout half of the correct torque outputof that brake. This is becausevoltage/current is almost linear totorque in DC electromagnetic brakes.

A constant current power supply isideal for accurate and maximum torquefrom a brake. If a non regulated powersupply is used the magnetic flux willdegrade as the resistance of the coilgoes up. Basically, the hotter the coilgets the lower the torque will be

produced by about an average of 8% for
http://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Currenthttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Current


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every 20C. If the temperature is fairlyconstant, and there is a question ofenough service factor in the design for

minor temperature fluctuation, byslightly over sizing the brake cancompensate for degradation. This willallow the use of a rectified powersupply, which is far less expensive thana constant current supply.

Based on V = I R, as resistanceincreases available current falls. Anincrease in resistance, often resultsfrom rising temperature as the coilheats up, according to: Rf = Ri [1 +

Cu (Tf - Ti)] Where Rf = final resistance, Ri = initial resistance, Cu = copper wires temperature coefficient ofresistance, 0.0039 C-1, Tf = finaltemperature, and Ti = initialtemperature.

Electromagnetic brakes is a newrevolutionary concept. They works onthe principle of electromagnetism.

These are totally frictionless.

Types of Electromagnetic Brakes

Electromagnetic Power Off Bra ke :


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Electormagnetic Power Off Brake Spring Set

Introduction - Power off brakes stop orhold a load when electrical power iseither accidentally lost or intentionallydisconnected. In the past, somecompanies have referred to these as"fail safe" brakes. These brakes are

typically used on or near an electricmotor. Typical applications includerobotics, holding brakes for Z axis ballscrews and servo motor brakes. Brakesare available in multiple voltages andcan have either standard backlash orzero backlash hubs. Multiple disks can

also be used to increase brake torque,
http://en.wikipedia.org/wiki/File:Electromagnetic_Power_Off_Brake.gif


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without increasing brake diameter.There are 2 main types of holdingbrakes. The first is spring applied

brakes. The second is permanentmagnet brakes.

How It Works :

Spring Type - When no electricity isapplied to the brake, a spring pushesagainst a pressure plate, squeezing the

friction disk between the inner pressureplate and the outer cover plate. Thisfrictional clamping force is transferredto the hub, which is mounted to a shaft.

Permanent Magnet Type A permanentmagnet holding brake looks very similar

to a standard power appliedelectromagnetic brake. Instead ofsqueezing a friction disk, via springs, ituses permanent magnets to attract asingle face armature. When the brake isengaged, the permanent magnetscreate magnetic lines of flux, which can

turn attract the armature to the brakehousing. To disengage the brake, poweris applied to the coil which sets up analternate magnetic field that cancelsout the magnetic flux of the permanentmagnets.

Both power off brakes are

considered to be engaged when no


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power is applied to them. They aretypically required to hold or to stopalone in the event of a loss of power or

when power is not available in amachine circuit. Permanent magnetbrakes have a very high torque for theirsize, but also require a constant currentcontrol to offset the permanentmagnetic field. Spring applied brakes donot require a constant current control,

they can use a simple rectifier, but arelarger in diameter or would needstacked friction disks to increase thetorque.

Electromagnetic Particle Brake :
http://upload.wikimedia.org/wikipedia/commons/8/8a/Electromagnetic_Particle_Brake.gif


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Electromagnetic Particle Brake

Introduction : Magnetic particle brakesare unique in their design from otherelectro-mechanical brakes because ofthe wide operating torque rangeavailable. Like an electro-mechanical

brake, torque to voltage is almostlinear; however, in a magnetic particlebrake, torque can be controlled veryaccurately (within

the operating RPM range of the unit).This makes these units ideally suited fortension control applications, such aswire winding, foil, film, and tape tensioncontrol. Because of their fast response,they can also be used in high cycle

applications, such as magnetic cardreaders, sorting machines and labelingequipment.

How It Works : Magnetic particles (verysimilar to iron filings) are located in the

powder cavity. When electricity is


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applied to the coil, the resultingmagnetic flux tries to bind the particlestogether, almost like a magnetic

particle slush. As the electric current isincreased, the binding of the particlesbecomes stronger. The brake rotorpasses through these bound particles.The output of the housing is rigidlyattached to some portion of themachine. As the particles start to bind

together, a resistant force is created onthe rotor, slowing, and eventuallystopping the output shaft.

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

shaft. Since magnetic particle powder isin the cavity, all magnetic particle unitshave some type of minimum dragassociated with them.

Electromagnetic Hysteresis PowerBrake :


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Electromagnetic Hysteresis Power Brake

Introduction : Electrical hysteresis unitshave an extremely wide torque range.Since these units can be controlledremotely, they are ideal for test standapplications where varying torque isrequired. Since drag torque is minimal,these units offer the widest availabletorque range of any of the hysteresisproducts. Most applications involvingpowered hysteresis units are in teststand requirements.

How It Works : When electricity isapplied to the field, it creates an

internal magnetic flux. That flux is then
http://upload.wikimedia.org/wikipedia/commons/d/d2/Electromagnetic_Hysteresis_Power_Brake.gif


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transferred into a hysteresis diskpassing through the field. Thehysteresis disk is attached to the brake

shaft. A magnetic drag on the hysteresisdisk allows for a constant drag, oreventual stoppage of the output shaft.

When electricity is removed from thebrake, the hysteresis disk is free toturn, and no relative force istransmitted between either member.Therefore, the only torque seenbetween the input and the output isbearing drag.

Multiple Disk Brakes :

Introduction : Multiple disk brakes areused to deliver extremely high torquewithin a small space. These brakes canbe used either wet or dry, which makesthem ideal to run in multi speed gearbox applications, machine tool

applications, or in off road equipment.


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Electromagnetic Multiple Disk Brake

How It Works : Electro-mechanical disk

brakes operate via electrical actuation,but transmit torque mechanically. Whenelectricity is applied to the coil of anelectromagnet, the magnetic fluxattracts the armature to the face of thebrake. As it does so, it squeezes theinner and outer friction disks together.

The hub is normally mounted on theshaft that is rotating. The brake housingis mounted solidly to the machineframe. As the disks are squeezed,torque is transmitted from the hub intothe machine frame, stopping andholding the shaft.
http://upload.wikimedia.org/wikipedia/en/b/bc/Multiple-disk-electromagnetic-brake1.gif


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When electricity is removed from thebrake, the armature is free to turn withthe shaft. Springs keep the friction disk

and armature away from each other.There is no contact between breakingsurfaces and minimal drag. Particlebrakes are unique in their design fromother electro-mechanical brakesbecause of the wide operating torquerange available. Like an electro-

mechanical brake, torque to voltage isalmost linear; however, in a magneticparticle brake, torque can be controlledvery accurately (within the operatingRPM range of the unit). This makesthese units ideally suited for tensioncontrol applications, such as wire

winding, foil, film, and tape tensioncontrol. Because of their fast response,they can also be used in high cycleapplications, such as magnetic cardreaders, sorting machines and labelingequipment.

How It Works : Magnetic particles (very

similar to iron filings) are located in thepowder cavity. When electricity isapplied to the coil, the resultingmagnetic flux tries to bind the particlestogether, almost like a magneticparticle slush. As the electric current isincreased, the binding of the particles

becomes stronger. The brake rotor


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passes through these bound particles.The output of the housing is rigidlyattached to some portion of the

machine. As the particles start to bindtogether, a resistant force is created onthe rotor, slowing, and eventuallystopping the output shaft.

When electricity is removed from thebrake, the input is free to turn with theshaft. Since magnetic particle powder isin the cavity, all magnetic particle unitshave some type of minimum dragassociated with them.

: PRODUCT DETAIL :

Electromagnetic brakes operateelectrically, but transmit torquemechanically. This is why they used to

be referred to as electro-mechanicalbrakes. Over the years, EM brakesbecame known as electromagnetic,referring to their actuation method.Since the brakes started becomingpopular over sixty years ago, the varietyof applications and brake designs has
http://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Brakeshttp://en.wikipedia.org/wiki/Brakehttp://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Brakeshttp://en.wikipedia.org/wiki/Brake


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increased dramatically, but the basicoperation remains the same.

Single face electromagnetic brakesmake up approximately 80% of all of thepower applied brake applications. Thisarticle mainly concentrates on thesebrakes. Alternative designs are shownat the end of this article.

Basic Operation :

There are three parts to anelectromagnetic brake: field, armature,and hub (which is the input on a brake)(B-2). Usually the magnetic field isbolted to the machine frame (or uses a

torque arm that can handle the torqueof the brake). So when the armature isattracted to the field the stoppingtorque is transferred into the fieldhousing and into the machine framedecelerating the load. This can happenvery fast (.1-3sec).
http://en.wikipedia.org/wiki/Fieldhttp://en.wikipedia.org/wiki/Armaturehttp://en.wikipedia.org/wiki/Hubhttp://en.wikipedia.org/wiki/Fieldhttp://en.wikipedia.org/wiki/Armaturehttp://en.wikipedia.org/wiki/Hub


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Disengagement is very simple. Oncethe field starts to degrade flux fallsrapidly and the armature separates. Aspring(s) hold the armature away fromits corresponding contact surface at apredetermined air gap.

Working principle :

The working principle of theElectromagnetic brakes is based on thecreation of currents within a metal discrotating between two electromagnets,which sets up a force opposing therotation of the disc .If the

electromagnet is not energized, therotation of the disc is free and
http://en.wikipedia.org/wiki/File:A-3_electromagnetic-brake1.gif


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accelerates uniformly. When theelectromagnet is energized, the rotationof the disc is retarded and the energy

absorbed appears as heating of thedisc. If the current exciting theelectromagnet is varied by a rheostat,the braking torque varies in directproportion to the value of the current.

Electromagnetic brakes satisfy all

the energy requirements of braking athigh speeds, completely without the useof friction. Electromagnetic brakes havebetter heat dissipation capability toavoid problems that friction brakes faceas we mentioned before. The brakes arefitted to vehicle by means of anti

vibration mounting.

Construction :

A horseshoe magnet (A-1) has anorth and south pole. If a piece of Ironcontacts both poles, a magnetic circuitis created. In an electromagnetic brake,the north and south pole is created by acoil shell and a wound coil. In a brake,the armature is being pulled against thebrake field. (A-3) The frictional contact,which is being controlled by thestrength of the magnetic field, is whatcauses the rotational motion to stop. All


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of the torque comes from the magneticattraction and coefficient offrictionbetween the steel of the armature and

the steel of the brake field. For manyindustrial brakes, friction material isused between the poles. The material ismainly used to help decrease the wearrate. But different types of material canalso be used to change the coefficient offriction (torque) for special applications.

For example, if the brake was requiredto have an extended time to stop or sliptime, a low coefficient material can beused. Conversely, if the brake wasrequired to have a slightly highertorque (mostly for low RPMapplications), a high coefficient friction

material could be used.In a brake, the electromagnetic lines

of flux have to attract and pull thearmature in contact with it to completebrake engagement. Most industrialapplications use what is called a single-flux two-pole brake. The coil shell is

made with carbon steel that has acombination of good strength and goodmagnetic properties. Copper(sometimes aluminum) magnet wire, isused to create the coil, which is held inshell either by a bobbin or by some typeof epoxy/adhesive.
http://en.wikipedia.org/wiki/Frictionhttp://en.wikipedia.org/wiki/Coefficient_of_frictionhttp://en.wikipedia.org/wiki/Coefficient_of_frictionhttp://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Aluminumhttp://en.wikipedia.org/wiki/Magnet_wirehttp://en.wikipedia.org/wiki/Bobbinhttp://en.wikipedia.org/wiki/Frictionhttp://en.wikipedia.org/wiki/Coefficient_of_frictionhttp://en.wikipedia.org/wiki/Coefficient_of_frictionhttp://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Aluminumhttp://en.wikipedia.org/wiki/Magnet_wirehttp://en.wikipedia.org/wiki/Bobbin


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To help increase life in applications,friction material is used between thepoles. This friction material is flush with

the steel on the coil shell, since if thefriction material was not flush, goodmagnetic traction could not occurbetween the faces. Some people look atelectromagnetic brakes and mistakenlyassume that, since the friction materialis flush with the steel, that the brake

has already worn down, but this is notthe case.

Advantages :

1. Electromagnetic brakes are more

durable.2. Electromagnetic brakes has alonger life span.

3. Electromagnetic brakes are muchmore effective.

4. Electromagnetic brakes workstotally frictionless.

5. Better cooling of brakes.6. There is less amount of wear.7. Maintenance required is

negligible.


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CIRCUIT DIAGRAM


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: Product Requirements :

Copper (For Winding). Aluminum or Cast Iron (for casing). Overall :

Power supply to power thesystem.

Hub and spindle assembly tosimulate the actual.

spinning of the rotor Custom made rotor with metal

arranged for themost effective result

Brake pedal to simulate the realenvironment

Three electromagnets to generatebraking force

Hardware and Software

8051 microcontroller Reading the braking level from pedal Varying the braking force through

duty cycle Custom built circuit board Regulating input voltage Powering up the 8051 c Amplifying the output voltage to

electromagnets


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: Machinery Required :

Drilling. Welding.

: FUTURE SCOPE :

A revolutionary invention is made inthe field of brakes. The Electromagneticbrakes are excellent replacement forconventional automobile brakes. Theuse of Electromagnetic brakes can bedone for lighter vehicles also. Withsome modification, a regenerativebraking system can be equipped withthe Electromagnetic brakes. TheElectromagnetic brakes are the futureof automobile brakes.


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: CONCLUSION :

Electromagnetic brakes can be usedfor modern Light as well as heavyvehicles. They give better performancewith enhanced safety.

: REFRENCES : Google search. Wikipedia.com Howstuffworks.com


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Electro Magnetic Brake