GOVERNMENT POLYTECHNIC COLLEGE

KONAM, NAGERCOIL 629004

KANYAKUMARI DISTRICT

PROJECT REPORT

ON

HYDRAULIC BRAKING SYSTEM IN

AUTOMOBILE

Submitted in partial fulfillment of the requirement for the award for the diploma

in Mechanical Engineering of the Directorate of Technical Education

Project guided by

A.PRABU, B.E

Submitted By

CHENTHIL RAJAN.C - 11800306

KRISHNA RAVI.S - 11800310

MARIAPPAN.E - 11800311

NAGARAJAN.T - 11800312

NAMBI VELAYUTHAM.G - 11800313

DEPARTMENT OF MECHANICAL

ENGINEERING

2013 2014

GOVERNMENT POLYTECHNIC COLLEGE

KONAM, NAGERCOIL 629004

KANYAKUMARI DISTRICT

BONAFIDE CERTIFICATE

This is to certified that this project work entitled HYDRAULIC

BRAKING SYSTEM IN AUTOMOBILE is Mr.

Reg. Noin Partial fulfillment of the requirement for the

award of diploma in Mechanical Engineering by Board of Technical Education

Government of Tamilnadu during the academic year by 2013-2014.

Mr. A. PRABU, B.E. Mr. M.AMEER BABU, M.E.

Staff in-charge. Head of the Department.

Submitted for the Project Viva-Voice Examination on .

INTERNAL EXAMINER EXTERNAL EXAMINER

ACKNOWLEDGEMENT

We are grateful of our Principal Mr. T. DAVIDSON, M.E., for granting

permission and having provided us all facilities to carry out this project

successfully.

We are expressing our whole hearted thanks to our Head of the

Department Mr. M.AMEER BABU, M.E, for his valuable guidance and

encouragement which helped us in accomplishing this project.

We are expressing our deep sense of guidance to our guide

Mr.A.PRABU, B.E. for his valuable Guidance and suggestion in processing

this project and completing it successfully within the stipulated time.

We would like to extend our gratitude to all staff members of Mechanical

Engineering Department for their kind encouragement and valuable

suggestions.

1

CONTENT

CHAPTER NO. TABLE OF CONTENT PAGE NO.

1 ABSTRACT 3

2 INTRODUCTION 4

3 BLOCK DIAGRAM 5

4 CONSTRUCION DETAILS 6

5 WORKING PRINCIPLE 10

6 FABRICATION OF PARTS 12

7 ADVANTAGE 22

8 APPLICATION 23

9 COST ESTIMATION 24

10 CONCLUSION 25

11 BIBLOGRAPHY 26

12 PHOTOGRAPHS 27

2

TABLE OF FIGURE

FIGURE NO. FIGURE NAME PAGE NO.

3.1 HYDRAULIC BRAKING SYSTEM 5

5.1 WORKING PRINCIPLE 10

6.3 SECTIONAL VIEW OF MASTER CYLINDER 13

6.5

METERING VALVE 17

6.8 ASSEMBLY OF WHEEL CYLINDER AND

BRAKE SHOE 19

6.10

WHEEL CYLINDER AND COMPONENTS. 20

3

1. ABSTRACT

The main objective of his project is to design a Hydraulic braking system

in automobile. In this project is specially designed to demonstrate the

Engineering Students, how the hydraulic braking system is worked.

In this project is to explain it all the parts of hydraulic braking system.

The some parts are sectioned for the use of visually see the parts, how to works

and easy to understand the working of parts.

This project is simple constructed for the purpose of portability,

and this project can be used all Engineering oriented institutions, colleges,

schools, etc.

4

2. INTRODUCTION

Automotive brakes are designed to slow and stop a vehicle by

transforming kinetic energy (motion energy) into heat energy. As the brake

linings contact the drums/rotors they create friction which produces the heat

energy. The intensity of the heat is proportional to the vehicle speed, the weight

of the vehicle, and the quickness of the stop. Faster speeds, heavier vehicles,

and quicker stops equal more heat.

The brake system constitutes an integral part of an automobile. It allows

the driver to slow or stop the vehicle and prevents a stationary vehicle from

moving. Failure of the automobile brake system can lead to accidents, property

damage, physical injuries or even death of an individual.

In recent years, brake systems have undergone tremendous changes in

terms of performance, technology, design and safety. Today, anti-lock braking

systems (ABS) are more or less standard. Modern ABS versions not only

prevent wheel lock under braking, but also electronically control the front-to-

rear brake bias. This function, depending on its specific capabilities and

implementation, is known as electronic brake force distribution (EBD), traction

control, emergency brake assist or electronic stability control system. A further

technological step change can be expected with the emergence of the brake-by-

wire technology.

5

3. BLOCK DIAGRAM

Fig No. 3.1

HYDRAULIC BRAKING SYSTEM

6

4. CONSTRUCTION DETAILS

IT CONSIST OF THE FOLLOWING COMPONENTS

1. MASTER CYLINDER

2. OIL TUBES

3. METERING VALVES

4. BRAKE FLUID

5. BRAKE DRUM

6. BRAKE SHOE

7. WHEEL CYLINDER

7

4.1. MASTER CYLINDER

The master cylinder provides the pressure to operate the other hydraulic

components. The master cylinder is in turn, operated by the foot pedal. Pushing

on the pedal creates a force on the pistons, creating hydraulic pressure.

4.2. OIL TUBES

The various components of the brake hydraulic system are connected

through lines and hoses. Lines are made of steel and hoses are made of braided

rubber. Lines connect the stationary parts of the hydraulic system and hoses

connect the parts which move in relation to each other.

4.3. METERING VALVE

The metering valve is used to keep the front brakes from applying before

the rear brakes. The fronts brake pads are not held in the retracted position by

springs are the rear brake shoes. Therefore, if the same amount of pressure

reached the front and rear brakes at the same time, the front brakes would do all

the stopping and wear prematurely. Applying only the front brakes could also

cause instability, or might throw the vehicle into a skid.

8

4.4. BRAKE FLUID

Brake fluid is a special liquid for use in hydraulic brake systems, which

must meet highly exact performance specifications. It is designed to be

impervious to wide temperature changes and to not suffer any significant

changes in important physical characteristics such as compressibility over the

operating temperature range. The fluid is designed to not boil, even when

exposed to the extreme temperatures of the brakes.

4.5. BRAKE DRUM

The brake drum provides a cast iron braking surface for the shoes to work

against. The drum also absorbs and dissipates large amounts of heat. Brake

drums are simple in construction and operation. The design differences between

various brake drums are discussed in the following paragraphs.

4.6. BRAKE SHOE

Brake shoes are made of two pieces of sheet steel welded together. The

friction material is attached to the lining table either by adhesive bonding or

riveting. The crescent shaped pieced is called the web and contains holes and

slots in different shapes for return springs.

9

Hold down hardware, parking brake linkages and self linkages

components. All the application force of the wheel cylinder is applied through

the web to the lining table and brake lining. The edge of the lining table

generally has three V shaped notches or tabs on each side called nibs. The

nips rest against the support pads of the backing plate to which the shoes are

installed.

4.7. WHEEL CYLINDER

The function of the wheel cylinder is to change hydraulic pressure from

the master cylinder into mechanical force that applies the brake shoes against

the rotating drum. Many types of wheel cylinders were used in the Past, but

modern vehicles use one wheel cylinder design, the single cylinder dual piston

or straight bore type. In this design, the cylinder' bore is one size throughout its

length, and has two pistons of equal size, one at each end. This type of wheel

cylinder changes hydraulic pressure into movement in two directions.

10

5. WORKING PRINCIPLE

In Hydraulic brake system when the brake pedal or brake lever is pressed,

a pushrod applies force on the piston in the master cylinder causing fluid from

the brake fluid tank to run into a pressure chamber through a balancing port

which results in increase in the pressure of whole hydraulic system. This forces

fluid through the hydraulic lines to one or more calipers where it works upon

one or two extra caliper pistons protected by one or more seated O-rings which

prevent the escape of any fluid from around the piston.

Fig No. 5.1 WORKING PRINCIPLE

The brake caliper piston then applies force to the brake pads. This causes

them to be pushed against the rotating rotor, and the friction between pads and

rotor causes a braking torque to be generated, slowing the vehicle. Heat created

11

from this friction is dispersed through vents and channels in rotor and through

the pads themselves which are made of particular heat-tolerant materials like

Kevlar, sintered glass, etc.

The consequent discharge of the brake pedal or brake lever lets the

spring(s) within the master cylinder assembly to return that assembly piston(s)

back into position. This reduces the hydraulic pressure on the caliper lets the

brake piston in the caliper assembly to slide back into its lodging and the brake

pads to discharge the rotor. If there is any leak in the system, at no point does

any of the brake fluid enter or leave.

12

6. FABRICATION PARTS

6.1. PEDAL LINKAGE

Although it is not a hydraulic part, the brake pedal linkage is vital to the

creation of hydraulic pressure. The brake pedal linkage increases foot pressure

by simple mechanical leverage. the pedal is part of a simple lever arrangement.

On a modern suspended pedal brake linkage, the connection to the master

cylinder rod, usually called the pushrod, is closer to the pivot point the an the

pedal. This increases the pedal force by mechanical leverage. The force on the

master cylinder is greater than the force placed on the brake pedal, but the

distance travelled is less. If for instance, the ratio is one to four (1 :4), pushing

the pedal 1" (25.4 mm) at a force of 10 psi (69 kPa), will result in a pressure on

the master cylinder piston of 40 psi (276 kPa) with a movement of 1/4" (6.4

mm).

6.2. MASTER CYLINDER

The master cylinder converts the motion of the brake pedal in to

hydraulic pressure. It consists the reservoir tank which contains the brake fluid;

and the piston and cylinder which generates the hydraulic pressure.

The reservoir tank is made mainly of synthetic resin, while the cylinders

are made of cast iron or an aluminum alloy

13

6.3. SECTIONAL VIEW OF MASTER CYLINDER

Fig No.6.3 SECTIONAL VIEW

14

6.4. MASTER CYLINDER COMPONENTS

The modern dual master cylinder has two separate pistons and chambers

for pressure development. Older vehicles used a single piston master cylinder,

discussed later in this chapter. Master cylinders are made of cast iron or

aluminum. Most modern master cylinders are made of aluminum.

Cast iron units are usually found in older vehicles and some current large

cars and light trucks. Pressure development in either type is the same. Most

master cylinders are installed on the firewall or brake booster unit with studs

passing through area,' mounting holes in the master cylinder. The master

cylinder is held by nuts threaded on the studs.

6.41. MASTER CYLINDER PISTON AND CUPS

The pistons used in the master cylinder are constructed of aluminum or

high impact plastic. Installed on the pistons are rubber cups, sometimes called

lip seals, The pistons also have springs which help to "return the pistons and the

brake pedal to their proper positions when the brakes are released. The cups and

springs may be separate units, or may be assembled onto the piston fanning a

complete assembly,

6.42. PRIMARY CUP

The inner (forward facing) end of each piston pushes against the primary

cup. The primary cup prevents brake fluid from leaking past the piston, which

could prevent the development of hydraulic pressure.

15

6.43. SECONDARY CUPS

The rear of each piston has a secondary cup. The secondary cup on the

front piston keeps pressure from leaking between the two chambers. The

secondary cup on the rear piston keeps brake fluid from leaking out the back of

the master cylinder. When the pistons move forward, pressure forces the cups

against the cylinder walls, and they seal in the developing pressure. When the

brake is released, the pistons move toward the rear. This causes the pressure to

drop and the cups flex inward, allowing fluid to enter from the rear of the

cylinder. Fluid flow is increased by the use of bleeder holes in the piston,

directly behind the cup.

6.44. RESERVOIR

Master cylinder' uses a reservoir to hold extra brake fluid. As the brake

pad and shoe linings become thinner, the apply pistons have to travel a longer

distance to bring them into contact with the drums and rotors.

To do this, the pistons must travel a longer distance, and require more

fluid. This extra fluid is supplied from the reservoir.

6.45. MASTER CYLINDER PORTS

At certain times, brake fluid must pass freely between the cylinder and

pistons and the reservoir. At other times, the reservoir" and cylinder must be sea

16

led from each other. This is accomplished by two ports drilled into the top of the

cylinder, the compensating port, and the inlet port.

As the piston returns to its resting position, brake fluid has forced the cup

seal away from the cylinder wall, allowing fluid to travel by the seal. (TRW

Inc.)

6.46. COMPENSATING PORT

The compensating port, sometimes called the bypass or vent port, is

located just ahead of the primary cup seal. It allows pressurized fluid in the

hydraulic system to return to the reservoir when the brakes are released. When

hydraulic pressure falls below atmospheric pressure, brake fluid can flow from

the reservoir through the compensating port and into the piston cylinder. This

keeps the system filled with fluid and ready to be pressurized again

6.47. INLET PORT

The inlet port, sometimes called the breather or intake port is located

farther back toward the rear area of each piston, always behind the primary seal.

This port is used to allow the entry of brake fluid into the rear section of the

piston cylinder. When the fluid pressure drops during brake release and the lip

seals flex inward, fluid is available to refill the pressure chamber.

17

6.5. METERING VALVE

Fig No.6.5. METERING VALVE

The metering valve is used to keep the front brakes from applying before

the rear brakes. The front brake pads are not held in the retracted position by

springs as

Auto Brakes are the rear brake shoes. Therefore, if the same amount of pressure

reached the front and rear brakes at the same time, the front brakes would do all

the stopping and wear prematurely. Applying only the front brakes could also

cause instability, or might throw the vehicle into a skid.

The metering valve assembly consists of a small spring-loaded valve. The

spring seats the valve against hydraulic pressure until a certain pressure is

reached. At this pressure the valve is unseated and fluid can flow to the disc

brake calipers. This delay in applying the front brakes gives the rear brakes time

to overcome spring pressure and begin applying the rear brakes.

18

6.6. BRAKE DRUM

The brake drum provides a cast iron braking surface for the shoes to work

against. The drum also absorbs and dissipates large amounts of heat. Brake

drums are simple in construction and operation.

6.7. BACKING PLATE

To provide a foundation for the drum brake components and to act as a

splash shield against water and road debris, a backing plate (sometimes called a

support plate) is used. The wheel cylinder, brake shoes, and springs are attached

to the backing plate.

6.8. SHOE AND WHEEL CYLINDER CONNECTIONS

There are two methods of connecting the wheel cylinder piston to the

shoe web. One method is by using a link, sometimes called a strut or pin,

between the piston and web. The link usually has a rounded end which contacts

the piston. The other end is slotted or grooved to fit securely against a matching

cutout on the web. The link passes through the wheel cylinder dust boot to

contact the piston.

19

Fig No.6.8

ASSEMBLY OF WHEEL CYLINDER AND BRAKE SHOE.

On the second design, the wheel cylinder piston directly contacts a

projection on the shoe web; Piston movement moves the shoe directly. The

wheel cylinder dust boot has a large center opening to allow the shoe projection

to touch the piston without damaging the boot.

6.9. RETURN SPRINGS

The two major types of drum brake springs are hold down springs and

return springs. The hold down springs hold the shoes against the backing plate,

while at the same time allowing them to move when the brakes are applied. The

return springs, sometimes called retracting springs, bring the shoes to the

unapplied position when hydraulic pressure is removed.

20

6.10. WHEEL CYLINDER CONSTRUCTION AND OPERATION

The wheel cylinder body is constructed of cast iron or aluminum. Dust

boots and piston seals are made of natural rubber. The wheel cylinder pistons

are usually made of aluminum or iron. Both the front and rear pistons are the

same size. Pistons vary greatly in both size and design.

In some wheel cylinders, the pistons contact the brake shoes directly. In

other designs, separate pushrods connect the pistons to the brake shoes. See

Figure 6.10

Fig No. 6.10

WHEEL CYLINDER AND COMPONENTS.

21

A hole is drilled and threaded near the center of the cylinder for a brake

line connection. A screw hole is added to fit a bleeder screw for air removal.

Typical wheel cylinder construction is illustrated in

As the brakes are applied, pressurized fluid enters the wheel cylinder

from the brake line. The pressure forces each piston outward. They, in turn,

force the brake shoes into contact with the brake drum. When pressure on the

brake pedal is released, the brake shoe return springs retract the shoes, and they

no longer contact the drum. As the springs retract the shoes, the wheel cylinder

pistons are forced back to their released position in the cylinder bore.

22

7. ADVANTAGES

1. Simple construction

2. Gives equal braking effort to all the wheels

3. Increased braking effort

4. High mechanical advantage

5. Self compensating system

6. Maintenance is easy

7. It allows smooth and easy application of brakes.

8. Due to absence of joints compared to mechanical brakes, rate of wear is

also less.

9. System is mostly self- lubricating

23

8. APPLICATIONS

1. Hydraulic brake system is used for all type of automobile vehicles.

2. Light duty vehicle.

3. Heavy duty vehicles.

4. Earth movers.

5. Two wheelers etc.

24

9. COST ESTIMATION

S.NO MATERIAL NAME

QUANTITY

(NOS)

AMOUNT

(RS)

1 MASTER CYLINDER ASSEMBLY 1 900

2 OIL TUBE (1feet) 7 200

3 BRAKE DRUM 4 800

4 BRAKE SHOE ASSEMBLY 1 1000

5 BRAKE PEDAL & LINKAGE 1 SET 200

6 BRAKE FLUID 1LTR 120

FABRICATION COST 1600

TOTAL COST 4820

25

10. CONCLUSION

We construct a project successfully. On completing the project we come

to a conclusion that constructing a mechanical project is good experience. We

know more about the latest technology exists in the mechanical world.

We also know how to construct, develop, integrate checkout, and

completing project.

26

11. BIBLIOGRAPHY

Dr. Kirpal Singh, Automobile Engineering vol-1, 13th

edition year 2013,

Standard publisher, Delhi.

Dr. Kirpal Singh, Automobile Engineering vol-2, 12th

edition year 2011,

Standard publisher, Delhi.

K.K. Jain & R.B. Asthana, Automobile Engineering, 5th

Edition for the

year of 2011, Tata McGraw Hill Education Private Limited, New Delhi.

William H. Crouse & Donald L. Anglin, Automotive Mechanics, 10th

Edition for the year of 2010, Tata McGraw Hill Education Private Limited, New

Delhi.

27

12. PHOTOGRAPHY