32
TABLE OF CONTENTS 1. Abstract 5 2. Introduction 6 3. How Brakes Work 7 4. Brake Basic 7 a. Leverage 8 b. Hydraulic 9 c. Friction 9 5. Simple Braking System 10 6. Types Of Brakes 10 a. Disc Brake 11 b. Drum Brakes 11 7. Types Of Disc Brake 11 a. Floating Caliper Disc Brake

Disc Brake System Report

Embed Size (px)

DESCRIPTION

Technical seminar report on DBS

Citation preview

Page 1: Disc Brake System Report

TABLE OF CONTENTS1. Abstract 52. Introduction 63. How Brakes Work 74. Brake Basic 7

a. Leverage 8b. Hydraulic 9c. Friction 9

5. Simple Braking System 106. Types Of Brakes 10

a. Disc Brake 11b. Drum Brakes 11

7. Types Of Disc Brake 11a. Floating Caliper Disc Brakeb. Fixed Caliper Disc Brakec. Sliding Caliper Disc Brake

8. Main parts of disc brakes 129. Working Of Disc Brake 1310. Self adjustment of disc brake 1511. Emergency Brakes 1512. Brake Fade 1613. Advantages 1814. Why are disc brakes more efficient ? 2115. Why do disc brakes have better braking behavior? 2216. Why do disk brakes have higher safety reserves? 2217. Limitations 2318. Testing Of Disc Brakes 2319. Conclusion 2420. References 25

Page 2: Disc Brake System Report

ABSTRACT:

The current tendencies in automotive industry need intensive investigation in problems of

interaction of active safety systems with brake system equipments. At the same time, the

opportunities to decrease the power take-off of single components, disc brake systems.Disc

brakes sometimes spelled as "disk" brakes, use a flat, disk-shaped metal rotor that spins with the

wheel. When the brakes are applied, a caliper squeezes the brake pads against the disc (just as

you would stop a spinning disc by squeezing it between your fingers), slowing the wheel.

The disc brake used in the automobile is divided into two parts: a rotating

axisymmetrical disc, and the stationary pads. The hydraulic brake is an arrangement of braking

mechanism which uses brake fluid, typically containing ethylene glycol, to transfer pressure

from the controlling unit, which is usually near the operator of the vehicle, to the actual brake

mechanism, which is usually at or near the wheel of the vehicle.

The frictional heat, which is generated on the interface of the disc and pads, can cause

high temperature during the braking process. Hence the automobiles generally use disc brakes on

the front wheels and drum brakes on the rear wheels. The disc brakes have good stopping

performance and are usually safer and more efficient than drum brakes.

The four wheel disc brakes are more popular, swapping drums on all but the most basic

vehicles. Many two wheel automobiles design uses a drum brake for the rear wheel. Brake

technology began in the '60s as a serious attempt to provide adequate braking for performance

cars has ended in an industry where brakes range from supremely adequate to downright

phenomenal.

One of the first steps taken to improve braking came in the early '70s when

manufacturers, on a widespread scale, switched from drum to disc brakes. Since the majority of a

vehicle's stopping power is contained in the front wheels, only the front brakes were upgraded to

disc during much of this period. Since then, many manufacturers have adopted four-wheel disc

brakes on their high-end and performance models as well as their low-line economy cars.

Occasionally, however, as in the case of the 1999 Mazda Protege's, a manufacturer will revert

from a previous four-wheel disc setup to drum brakes for the rear of the car in order to cut both

production costs and purchase price.

Page 3: Disc Brake System Report

INTRODUCTION

HISTORY OF DISK BRAKE

Ever since the invention of the wheel, if there has been "go" there has been a need for

"whoa." As the level of technology of human transportation has increased, the mechanical

devices used to slow down and stop vehicles has also become more complex. In this report I will

discuss the history of vehicular braking technology and possible future developments.

Before there was a "horse-less carriage," wagons, and other animal drawn vehicles relied

on the animal’s power to both accelerate and decelerate the vehicle. Eventually there was the

development of supplemental braking systems consisting of a hand lever to push a wooden

friction pad directly against the metal tread of the wheels. In wet conditions these crude brakes

would lose any effectiveness.

The early years of automotive development were an interesting time for the designing

engineers, "a period of innovation when there was no established practice and virtually all ideas

were new ones and worth trying. Quite rapidly, however, the design of many components

stabilized in concept and so it was with brakes; the majority of vehicles soon adopted drum

brakes, each consisting of two shoes which could be expanded inside a drum."

In this chaotic era is the first record of the disk brake. Dr. F.W. Lanchester patented a

design for a disk brake in 1902 in England. It was incorporated into the Lanchester car produced

between 1906 through 1914. These early disk brakes were not as effective at stopping as the

contemporary drum brakes of that time and were soon forgotten. Another important development

occurred in the 1920’s when drum brakes were used at all four wheels instead of a single brake

to halt only the back axle and wheels such as on the Ford model T. The disk brake was again

utilized during World War II in the landing gear of aircraft. The aircraft disk brake system was

adapted for use in automotive applications, first in racing in 1952, then in production

automobiles in 1956. United States auto manufacturers did not start to incorporate disk brakes in

lower priced non-high-performance cars until the late 1960’s.

Page 4: Disc Brake System Report

HOW BRAKES WORK

We all know that pushing down on the brake pedal slows a car to a stop. But how does

this happen? How does your car transmit the force from your leg to its wheels? How does it

multiply the force so that it is enough to stop something as big as a car?

BRAKE BASICS

When you depress your brake pedal, your car transmits the force from your foot to its

brakes through a fluid. Since the actual brakes require a much greater force than you could apply

with your leg, your car must also multiply the force of your foot. It does this in two ways:

Mechanical advantage (leverage)

Hydraulic force multiplication

The brakes transmit the force to the tires using friction, and the tires transmit that force to the

road using friction also. Before we begin our discussion on the components of the brake system,

let's cover these three principles:

Page 5: Disc Brake System Report

Leverage

Hydraulics

Friction

LEVERAGE

The pedal is designed in such a way that it can multiply the force from your leg several

times before any force is even transmitted to the brake fluid.

In the figure above, a force F is being applied to the left end of the lever. The left end of

the lever is twice as long (2X) as the right end (X). Therefore, on the right end of the lever a

force of 2F is available, but it acts through half of the distance (Y) that the left end moves (2Y).

Changing the relative lengths of the left and right ends of the lever changes the multipliers.

HYDRAULIC SYSTEMS The basic idea behind any hydraulic system is very simple: Force applied at one point is

Page 6: Disc Brake System Report

transmitted to another point using an incompressible fluid, almost always an oil of some sort.

Most brake systems also multiply the force in the process

FRICTION

Friction is a measure of how hard it is to slide one object over another. Take a look at the

figure below. Both of the blocks are made from the same material, but one is heavier. I think we

all know which one will be harder for the bulldozer to push.

Friction force versus weight

To understand why this is, let's take a close look at one of the blocks and the table:

Even though the blocks look smooth to the naked eye, they are actually quite rough at the

microscopic level. When you set the block down on the table, the little peaks and valleys get

squished together, and some of them may actually weld together. The weight of the heavier

block causes it to squish together more, so it is even harder to slide.

Different materials have different microscopic structures; for instance, it is harder to slide

rubber against rubber than it is to slide steel against steel.

Page 7: Disc Brake System Report

The type of material determines the coefficient of friction, the ratio of the force required

to slide the block to the block's weight. If the coefficient were 1.0 in our example, then it would

take 100 pounds of force to slide the 100-pound (45 kg) block, or 400 pounds (180 kg) of force

to slide the 400-pound block. If the coefficient were 0.1, then it would take 10 pounds of force to

slide to the 100-pound block or 40 pounds of force to slide the 400-pound block.

So the amount of force it takes to move a given block is proportional to that block's

weight. The more weight, the more force required. This concept applies for devices like brakes

and clutches, where a pad is pressed against a spinning disc. The more force that presses on the

pad, the greater the stopping force.

A SIMPLE BRAKE SYSTEM

The distance from the pedal to the pivot is four times the distance from the cylinder to the

pivot, so the force at the pedal will be increased by a factor of four before it is transmitted to the

cylinder.

The diameter of the brake cylinder is three times the diameter of the pedal cylinder. This

further multiplies the force by nine. All together, this system increases the force of your foot by a

factor of 36. If you put 10 pounds of force on the pedal, 360 pounds (162 kg) will be generated at

the wheel squeezing the brake pads.

There are a couple of problems with this simple system. What if we have a leak? If it is a

slow leak, eventually there will not be enough fluid left to fill the brake cylinder, and the brakes

will not function. If it is a major leak, then the first time you apply the brakes all of the fluid will

squirt out the leak and you will have complete brake failure.

TYPES OF BRAKES

1. DRUM BRAKES

Page 8: Disc Brake System Report

2. DISC BRAKES (CALLIPER BRAKES)

DRUM BRAKES :-

The drum brake has two brake shoes and a piston. When you hit the brake pedal, the piston

pushes the brake shoes against the drum This is where it gets a little more complicated. as the

brake shoes contact the drum, there is a kind of wedging action, which has the effect of pressing

the shoes into the drum with more force. The extra braking force provided by the wedging action

allows drum brakes to use a smaller piston than disc brakes. But, because of the wedging action,

the shoes must be pulled away from the drum when the brakes are released. This is the reason for

some of the springs. Other springs help hold the brake shoes in place and return the adjuster arm

after it actuates.

DISK BRAKE BASICS:-

The disk brake has a metal disk instead of a drum. It has a flat shoe, or pad, located

on each side of the disk. To slow or stop the car, these two flat shoes are forced tightly against

the rotating disk, or rotor. Fluid pressure from the master cylinder forces the pistons to move in.

This action pushes the friction pads of the shoes tightly against the disk. The friction between the

shoes and the disk slows and stops the disk.

TYPES OF DISK BRAKES

The Three Types Of Disk Brakes Are:-

1. FLOATING CALIPER DISK BRAKES

2. FIXED CALIPER DISK BRAKES

3. SLIDING CALIPER DISK CALIPER

MAIN PARTS:

The main components of a disc brake are:

Page 9: Disc Brake System Report

The brake pads

The caliper, which contains a piston

The rotor, which is mounted to the hub

BRAKE PAD

CALIPER AND ROTOR

WORKING OF DISC BRAKES

FLOATING-CALIPER DISK BRAKES

Page 10: Disc Brake System Report

The caliper is the part that holds the break shoes on each side of the disk. In

the floating-caliper brake, two steel guide pins are threaded into the steering-knuckle adapter.

The caliper floats on four rubber bushings which fit on the inner and outer ends of the two guide

pins. The bushings allow the caliper to swing in or out slightly when the brakes are applied

When the brakes are applied, the brake fluid flows to the cylinder in the caliper and

pushes the piston out. The piston then forces the shoe against the disk. At the same time, the

pressure in the cylinder causes the caliper to pivot inward. This movement brings the other shoe

into tight contact with the disk. As a result, the two shoes “pinch” the disk tightly to produce the

braking action

STAGES OF WORKING

Page 11: Disc Brake System Report

FIXED-CALIPER DISK BRAKE

This brake usually has four pistons, two on each side of the disk. The reason for the

name fixed-caliper is that the caliper is bolted solidly to the steering knuckle. When the brakes

are applied, the caliper cannot move. The four pistons are forced out of their caliper bores to

push the inner and outer brake shoes in against the disk. Some brakes of this type have used only

two pistons, one on each side of the disk

SLIDING-CALIPER DISK BRAKE

The sliding-caliper disk brake is similar to the floating-caliper disk brake. The

difference is that sliding-caliper is suspended from rubber bushings on bolts. This permits the

caliper to slide on the bolts when the brakes are applied.

Proper function of the brake depends on (1) the rotor must be straight and smooth, (2) the

caliper mechanism must be properly aligned with the rotor, (3) the pads must be positioned

correctly, (4) there must be enough "pad" left, and (5) the lever mechanism must push the pads

tightly against the rotor, with "lever" to spare.

Most modern cars have disc brakes on the front wheels, and some have disc brakes on all four

wheels. This is the part of the brake system that does the actual work of stopping the car

The most common type of disc brake on modern cars is the single-piston floating caliper.

In this article, we will learn all about this type of disc brake design

SELF ADJUSTMENT OF DISK BRAKES:

Page 12: Disc Brake System Report

Disk brakes are self adjusting. Each piston has a seal on it to prevent fluid

leakage. When the brakes are applied, the piston moves toward the disk. This distorts the piston

seal. When the brakes are released, the seal relaxes and returns to its original position. This pulls

the piston away from the disk. As the brakes linings wear, the piston over travels and takes a new

position in relation to the seal. This action provides self adjustment of disk brakes.

EMERGENCY BRAKES

In cars with disc brakes on all four wheels, an emergency brake has to be actuated by a

separate mechanism than the primary brakes in case of a total primary brake failure. Most cars

use a cable to actuate the emergency brake.

Some cars with four-wheel disc brakes have a separate drum brake integrated into the hub of the

rear wheels. This drum brake is only for the emergency brake system, and it is actuated only by

the cable; it has no hydraulics.

BRAKE FADE

Vehicle braking system fade, or brake fade, is the reduction in stopping power that can

occur after repeated or sustained application of the brakes, especially in high load or high speed

Page 13: Disc Brake System Report

conditions. Brake fade can be a factor in any vehicle that utilizes a friction braking system

including automobiles, trucks, motorcycles, airplanes, and even bicycles.

Brake fade is caused by a buildup of heat in the braking surfaces and the subsequent changes and

reactions in the brake system components and can be experienced with both drum brakes and

disc brakes. Loss of stopping power, or fade, can be caused by friction fade, mechanical fade, or

fluid fade. Brake fade can be significantly reduced by appropriate equipment and materials

design and selection, as well as good cooling.

Brake fade occurs most often during high performance driving or when going down a long, steep

hill. Owing to their configuration fade is more prevalent in drum brakes. Disc brakes are much

more resistant to brake fade and have come to be a standard feature in front brakes for most

vehicles.

BRAKE MODIFICATION TO REDUCE FADE

High performance brake components provide enhanced stopping power by improving friction

while reducing brake fade. Improved friction is provided by lining materials that have a higher

coefficient of friction than standard brake pads, while brake fade is reduced through the use of

more expensive binding resins with a higher melting point, along with slotted, drilled, or dimpled

discs/rotors that reduce the gaseous boundary layer, in addition to providing enhanced heat

dissipation. Heat buildup in brakes can be further addressed by body modifications that direct

cold air to the brakes.

The "gaseous boundary layer" is a hot rod mechanics explanation for failing self servo effect of

drum brakes because it felt like a brick under the brake pedal when it occurred. To counter this

effect, brake shoes were drilled and slotted to vent gas. In spite of that, drum brakes were

abandoned for their self-servo effect. Disks do not have that because application force is applied

at right angles to the resulting braking force. There is no interaction.

Drum brake fade can be reduced and overall performance enhanced somewhat by an old "hot

rodder" technique of drum drilling. A carefully chosen pattern of holes is drilled through the

Page 14: Disc Brake System Report

drum working section; drum rotation centrifugally pumps a small amount air through the shoe to

drum gap, removing heat; fade caused by water-wet brakes is reduced since the water is

centrifugally driven out; and some brake-material dust exits the holes. Brake drum drilling

requires careful detailed knowledge of brake drum physics and is an advanced technique

probably best left to professionals. There are performance-brake shops that will make the

necessary modifications safely.

DISK BRAKE VENTS

A moving car has a certain amount of kinetic energy, and the brakes have to remove this energy

from the car in order to stop it. How do the brakes do this? Each time you stop your car, your

brakes convert the kinetic energy to heat generated by the friction between the pads and the disc.

Most car disc brakes are vented.

Brake fade caused by overheating brake fluid (often called Pedal Fade) can also be reduced

through the use of thermal barriers that are placed between the brake pad and the brake caliper

piston, these reduce the transfer of heat from the pad to the caliper and in turn hydraulic brake

fluid. Some high-performance racing calipers already include such brake heat shields made from

titanium or ceramic materials. However, it is also possible to purchase aftermarket titanium

brake heat shields [6] that will fit your existing brake system to provide protection from brake

Page 15: Disc Brake System Report

heat. These inserts are precision cut to cover as much of the pad as possible. These Titanium

Brake shims are an easy to install, low cost solution that are popular with racers and track day

enthusiasts.

Another technique employed to prevent brake fade is the incorporation of fade stop brake

coolers. Like titanium heat shields the brake coolers are designed to slide between the brake pad

backing plate and the caliper piston. They are constructed from a high thermal conductivity, high

yield strength metal composite which conducts the heat from the interface to a heat sink which is

external to the caliper and in the airflow. They have been shown to decrease caliper piston

temperatures by over twenty percent and to also significantly decrease the time needed to cool

down.[7] Unlike titanium heat shields, however, the brake coolers actually transfer the heat to the

surrounding environment and thus keep the pads cooler.

ADVANTAGES OF DISC BRAKES OVER DRUM BRAKES

As with almost any artifact of technology, drum brakes and disk brakes both have

advantages and disadvantages. Drum brakes still have the edge in cheaper cost and lower

complexity. This is why most cars built today use disk brakes in front but drum brakes in the

back wheels, four wheel disks being an extra cost option or shouted as a high performance

feature. Since the weight shift of a decelerating car puts most of the load on the front wheels, the

usage of disk brakes on only the front wheels is accepted manufacturing practice.

Drum brakes had another advantage compared to early disk brake systems. The geometry

of the brake shoes inside the drums can be designed for a mechanical self-boosting action. The

rotation of the brake drum will push a leading shoe brake pad into pressing harder against the

drum. Early disk brake systems required an outside mechanical brake booster such as a vacuum

assist or hydraulic pump to generate the pressure for primitive friction materials to apply the

necessary braking force.

Page 16: Disc Brake System Report

All friction braking technology uses the process of converting the kinetic energy of a

vehicle’s forward motion into thermal energy: heat. The enemy of all braking systems is

excessive heat. Drums are inferior to disks in dissipating excessive heat:

"The common automotive drum brake consists essentially of two shoes which may be expanded

against the inner cylindrical surface of a drum.

The greater part of heat generated when a brake is applied has to pass through the drum

to its outer surface in order to be dissipated to atmosphere, and at the same time (the drum is)

subject to quite severe stresses due to the distortion induced by the opposed shoes acting inside

the open ended drum.

The conventional disk brake, on the other hand, consists essentially of a flat disk on

either side of which are friction pads; equal and opposite forces may be applied to these pads to

press their working surfaces into contact with the braking path of the disks. The heat produced

by the conversion of energy is dissipated directly from the surfaces at which it is generated and

the deflection of the braking path of the disk is very small so that the stressing of the material is

not so severe as with the drum."

The result of overheated brakes is brake fade...the same amount of force at the pedal no

longer provides the same amount of stopping power. The high heat decreases the relative

coefficient of friction between the friction material and the drum or disk. Drum brakes also suffer

another setback when overheating: The inside radii of the drum expands, the brake shoe outside

radii no longer matches, and the actual contact surface is decreased.

Another advantage of disk brakes over drum brakes is that of weight. There are two

different areas where minimizing weight is important. The first is unsprung weight. This is the

total amount of weight of all the moving components of a car between the road and the

suspension mounting points on the car’s frame.

Auto designs have gone to such lengths to reduce unsprung weight that some, such as the

E-type Jaguar, moved the rear brakes inboard, next to the differential, connected to the drive

shafts instead of on the rear wheel hubs. The second "weighty" factor is more of an issue on

Page 17: Disc Brake System Report

motorcycles: gyroscopic weight. The heavier the wheel unit, the more gyroscopic resistance to

changing direction. Thus the bike’s steering would be higher effort with heavier drum brakes

than with lighter disks. Modern race car disk brakes have hollow internal vents, cross drilling

and other weight saving and cooling features.

Most early brake drums and disks were made out of cast iron. Current OEM motorcycle

disk brakes are usually stainless steel for corrosion resistance, but after-market racing component

brake disks are still made from cast iron for the improved friction qualities. Other exotic

materials have been used in racing applications. Carbon fiber composite disks gripped by carbon

fiber pads were common in formula one motorcycles and cars in the early 1990’s, but were

outlawed by the respective racing sanctioning organizations due to sometimes spectacular

failure. The carbon/carbon brakes also only worked properly at the very high temperatures of

racing conditions and would not get hot enough to work in street applications.

A recent Ducati concept show bike uses brake disks of selenium, developed by the

Russian aerospace industry(3), which claim to have the friction coefficient of cast iron with the

light weight of carbon fiber.

Another area of development of the disk brake is the architecture of the brake caliper.

Early designs had a rigidly mounted caliper gripping with opposed hydraulic pistons pushing the

brake pads against a disk mounted securely to the wheel hub. Later developments included a

single piston caliper floating on slider pins. This system had improved, more even pad wear.

Most modern automobiles and my 1982 Kawasaki motorcycle uses this type caliper. Current

design paradigm for motorcycle brakes have up to six pistons, opposed to grip both sides of a

thin, large radius disk that is "floating" on pins to provide a small amount of lateral movement;

two disks per front wheel.

Improvements in control have been made available with the application of Anti-Lock

Brake technology. Wheel sensors convey rotation speed of each wheel to a computer that senses

when any of them are locked up or in a skid, and modulates individual wheel brake hydraulic

pressure to avoid wheel skidding and loss of vehicular control.

Page 18: Disc Brake System Report

The use of exotic materials for additional weight savings would be likely for the future of

motor vehicle braking. Disks mounted to the wheel’s rim gripped by an internally located caliper

is not necessarily a new design (Porsche, 1963) (4) but could be a futuristic looking option for

motorcycle wheels. Electric vehicles of the future will likely utilize regenerative braking, the

electric motors become generators to convert kinetic energy back to electricity to recharge the

batteries. As production vehicles become increasingly quicker, the need for "whoa" will always

accompany the "go."

Why are disk brakes more efficient?

Flat brake disk (axial brake) under high pressure versus round brake drum (radial brake)

during braking

Full friction surface of the brake pad on the plane brake disk .

No loss of brake power due to overheating or partial contact from brake drum parts

expansion .

Disk brakes can withstand higher loads and its efficiency is maintained considerably

longer even under the highest stresses

Higher residual brake force after repeating braking

Brake disks can withstand extremely high temperatures

Full contact of brake pads achieve maximum effect

No verification of brake pads. Dangerous fading or slipping is almost completely

eliminated

Why do disk brakes have a better braking behavior?

Driver friendly braking behavior. Sensitive braking in all situations and better

Sensitive brake application and better brake feeling

Uniform braking from small fluctuations in brake forces

Page 19: Disc Brake System Report

Retardation values retained even under heavy stresses

Minimal "pulling to one side" due to uneven brake forces

Disk brake axial arrangement permits a simple and compact design

Linear characteristics lead to an even progression of brake force

Basic design principle makes for higher efficiency

Low hysteresis is particularly suitable to ABS control cycles

Why do disk brakes have higher safety reserves?

Minimal braking effect from high temperatures and extreme driving requirements

Minimal heat fading

No brake disk distortion from extreme heat due to internal ventilation with

directional stability and large power reserve under high stress

The decisive safety aspects of the disk brake design are shorter braking distances

High power and safety reserves for emergencies

Constant braking power under high stresses

Shortened braking distance under emergency braking with considerably improved

directional stability

LIMITATIONS

BRAKING SYSTEMS FAILS IF THERE IS LEAKAGE IN THE BRAKE LINES

THE BRAKE SHOES ARE LIABLE TO GET RUINED IF THE BRAKE FLUID

LEAKES OUT

Page 20: Disc Brake System Report

TESTING OF DISK BRAKES

The individual components are subjected to extensive test on the test bed. The optimum

arrangement of components on the axle beam, operational reliability and convincing

performance are requirements that must be met prior series production.

Today, all MAN city, inter-city buses and coaches utilize the MAN disk brake system on

all wheels with ABS. The disk brake system is used with and without retarders

Brake performance is tested on the test track and in racing to ensure their practice. Only

after these extensive tests can the disk brake be cleared for production .

The brake disks are subjected to the highest stresses from contact pressure. The broad

brake disks with radial cavities made of heat resistant special gray cast iron, are still operational

in temperatures in excess of 1380 degrees F

CONCLUSION

Many trucks and buses are equipped with air actuated sliding caliper disk brakes

The high contact forces are transmitted mechanically via needle mounted actuating device

Page 21: Disc Brake System Report

Depending on size the actuating pressure is transmitted evenly to the brake pads via one or two

plungers

The easy action, fully sealed guides between the axially moving sliding caliper and fixed

brake anchor plate are maintenance free. Integrated automatic adjustment with wear display.

There are no brake shafts, external levers or cylinder brackets, as the brake cylinders are directly

attached.

The high efficiency of 95% is achieved by only a few moving parts and low friction

bearings Asbestos free brake pads 19 to 23 mm thick, depending on version extremely heat

resistant brake disks (34 to 45 mm) made of special gray cast iron with internal ventilation

The brake disks are 330 to 432 mm in diameter and permissible wear of 6 to 10 mm

allowed; depending on version .The service and parking brakes use the same actuating unit and

differ only in the shape of the brake cylinder.

REFERENCES

Tech Center By Karl Brauer, Editor in Chief, Edmunds.com

http://cars.about.com/od/thingsyouneedtoknow/ig/Disc-brakes

Page 22: Disc Brake System Report

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

http://www.kobelt.com/pdf/brochure_brake.pdf

http://auto.howstuffworks.com/auto-parts/brakes/brake-types/disc-brake.htm

http://www.sae.org/search?searchfield=brake%20system

http://www.hinduonnet.com/thehindu/2000/05/25/ceramic brake disc

Automotive Engineering International Online Global Viewpoints, Nov_ 1999