HYDRAULIC BRAKING SYSTEMS

HYDRAULIC BRAKING SYSTEMS

KAJA KRISHNA PHANI

BTE-09-020

AGRICULTURAL ENGINEERING COLLEGE & RESEARCH INSTITUTE

TAMILNADU AGRICULTURAL UNIVERSITY

The technology of controlling pressurized fluids to create

force and motion is known as Hydraulics .

HYDRAULIC PRINCIPLES:

Fluids cannot be compressed

Fluids can transmit Movement

Acts “Like a steel rod” in a closed container

Master cylinder transmits fluid to wheel cylinder or caliper piston bore.

Fluids can transmit and increase force

PRESSURE =FORCE / AREA

Kinetic Energy as a Function of Speed and Mass

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

180,000

30 60 90 120Speed kph

Ene

rgy

N-M

200 kg

250 kg

290 kg

Of course ,the final contact between vehicle and road made through tyres -hence it is of great importance in braking system.

Bald or defective tyres will even make the best brakes ineffective.

The braking systems which works with the help of hydraulic

principles is known as hydraulic braking systems.

HYRAULIC BRAKING SYSTEM CAN BE OPERATED BY

Vacuum, Hydro or Motor assisted

Disc System

Drum System

Dual System

DRUM BRAKE

MASTER CYLINDER

DISK BRAKE

BRAKE PEDAL

HYDRAULIC PRESSURE IS DISTRIBUTED EQUALLY IN ALL DIRECTIONS

BY THE SAME PRINCIPLE ……….

SAME LINE OF PRESSURE WILL BE EXERTED ON ALL WHEELS

The Hydraulic pressure is the same, but the applied force can be changed by the piston size.

The applied

pressure can be

raised or

lowered by

piston size

Provides a reservoir for brake fluid and contains the driving pistons in the hydraulic circuitTHEY ARE OF 2 TYPES

Front - Rear split

-One piston for front brakes and one for rear

-If a leak occurs you could lose front brakes

Diagonally split

-One piston drives one front wheel and one rear wheel

-Diagonal layout allows you to maintain directional control if a leak occurs

MASTER CYLINDER

DRUM BRAKES

Expanding shoes create force on the inner surface of the drum

Used on the rear of some trucks and SUV’s

Self-energizing design requires less activation force

Require periodic adjustment

DISC BRAKES

DISK BRAKES WORKS WITH THE HELP OF CALIPERS

FIXED CALIPERS Calipers are disc brakes that use a caliper that is FIXED

in position and does not slide.

-They have pistons on both sides of the disc.

-There may be 2 or 4 pistons per caliper

FLOATING CALIPERS-Much more common

-Single Piston

-Easier to work with

-On “inboard” side of caliper

Calipers are of two types

FIXED CALIPER

Applies two pistons to opposite sides of rotor

Caliper stays stationary

Disc Brakes require higher hydraulic pressure

APPLICATIONS-Motorcycles and some import trucks and cars use this type

-Similar to bicycle brakes

.Applies pressure to two pads on opposite sides of rotor

.Caliper

-Sliding -Fixed

.Friction Material exposed to air

SLIDING CALIPER

FRONT WHEEL LOCK

THIS CONDITION WILL OCCUR IF THERE IS MORE FRONT BRAKE TORQUE

THAN DYNAMIC FRONT WEIGHT

REAR WHEEL LOCK

THIS CONDITION WILL OCCUR IF THERE IS MORE REAR TORQUE THAN DYNAMIC REAR WEIGHT

OPTIMUM BRAKING

Optimum braking is achieved when brake torque distribution matches

dynamic weight distribution

TO ACHIEVE THIS CONDITION PROPORTIONATING VALVES ARE USED

When a vehicle brakes , weight is transferred to the front.the nose will dip as it gets heavier and rear will rise as it gets lighter.The rear needs less hydraulic pressure.

Proportionating valves are used to provide balanced braking

by reducing hydraulic pressure to rear wheel

When a large variation at axle loading takes place, such as railway wagons ,

trucks ,load or height sensitive proportionating valves regulate more hydraulic

pressure to the rear axle in the amount needed.

Some vehicles with front/ rear split braking systems have a proportionating

valve by-pass which allows full pressure to rear axle if front brakes fails.

SOME TYPES OF PROPORTIONATING VALVES

BRAKE BOOSTER OR SERVO UNIT

Mounted on firewall between the brake pedal and master cylinder ,brake boosters

vary in size andd can be single or double diaphragm

POWER BOOSTER IN CLOSED POSITION

Brake booster have two chambers :one at front which is always at constant and

another at the rear where pressure varies they are by a pressure plate and are

sealed from one another by a rubber diaphragm.

There is a vacuum in the manifold of all 4-stroke petrol engines .Boosters use

this increase the force applied to master cylinder from 3- 5 times without loos

-ing brake sensitivity or response and with reduced pedal effort.

On diesel engines, an auxiliary vacuum pump is utilised to supply vacuum.

If the engine stops this will retain enough vacuum in the booster for upto 3

brake applications.

TYPES OF BOOSTERS

Properties of Brake Fluid

Does not thicken or then with changing heat

Must not boil

Must be compatible with brake parts material

Must lubricate internal parts

Must not evaporate easily

BRAKE FLUID

The fluid through which the energy is passed in hydraulic braking systems is

known as BRAKE FLUID

REFERENCE:

www.parker.com

www.google.co.in

THANK YOU