Braking system, types and classification of braking system, applications etc.

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KNOWLEDGE SHARING SESSION
On BRAKING SYSTEMS
SATHISHKUMAR S
(24-01-18)

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Main functions of braking system :
 To stop the vehicle safely in shortest possible
distance in case of emergency.
 To control the vehicle when it is descending along
the hills.
Braking system
 Brake is a device used for slowing, stopping & controlling
the vehicle.
Principle of braking system :
 Braking operation based on kinetic energy of vehicle is
 to converting into heat, which dissipated into
atmosphere.

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There are two layouts of braking systems used in cars and light trucks.
1. Front/Rear hydraulic split:
Also called axle by axle, vertical, and some times “black and white”.
2. Diagonal Split:
Also called criss-cross.
The type of split is only significant in the event of a hydraulic system
failure.
Layout of braking system

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Primary SystemPrimary System
Front Axle
Rear Axle
Secondary SystemSecondary System
Front/rear Hydraulic Split

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In a diagonal split system, one brake line is run
to
each rear brake and one to each front brake.
The connections are such that the left front
and the right rear brake are on one circuit and
the right front and left rear are on the other
circuit
Diagonal Split System

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Right front
left rear
Left front
right rear
Typical Diagonal Split System

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PRIMARY
SECONDARY
MECHANICAL
HYDRAULIC
AIR
VACUM
INBOARD
OUTBOARD
DISC
DRUM

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Components used in braking system:
 Brake Pedal
 Master booster
 Master cylinder
 Brake lines

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The Brake Pedal
Output to master cylinder
400 N and 36 mm
4:1 Nominal
Pedal Ratio
100 N and 144 mm
Driver Input
Input Torque = 100 N * 144 mm
= 14400 Nmm
Output Torque = 400 N * 36 mm
= 14400 Nmm

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Master Cylinders
A master cylinder is just a simple piston
inside a cylinder
Output Pressure
Input Force

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Loss of brake fluid through leaks or broken
brake lines can be a cause of brake failure.
One half of the system is lost when the
primary system fails. However, initial pedal
movement causes the unrestricted primary
piston to bottom against the secondary
piston. Continued movement of the pedal
moves the secondary piston mechanically to
displace fluid and transmit pressure to
actuate the brakes connected to the
secondary system.
The pedal travel will increase by a large
amount. To activate the remaining system
the brake pedal must be pushed well past
the position for normal braking. Pumping
the pedal will do no good and will not
activate the second hydraulic system.
M/C Applied
M/C Unapplied
Primary System Failure

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 Double wall steel tubing (Bundy Tubing) is
industry standard.
 3/16” o.d. is standard size.
 Very robust, can take a lot of abuse
 Use SAE 45° inverted flare (J533 and J512) joints
if you can.
Brake Lines

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• Linings are bonded or riveted to disc backing.
• The output of any brake is directly related to the
coefficient of friction (µ) between the lining and the disc
or drum.
• Lining types
– Asbestos linings: health hazard
– Semi metallic linings: sponge iron and steel fibers
– Metallic linings: used in heavy-duty and racing
conditions
– Ceramic linings: use ceramic and copper fibers to
control heat
Brake Lining

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Hydraulic Brake Fluid
• Glycol-based fluids are hygroscopic
– Absorb water
• Brake fluid
– Higher boiling point than water
• DOT specifications
– List both dry and wet boiling points

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HYDRAULLIC BRAKING SYSTEM
PNEUMATIC BRAKING SYTEM
MECHANICAL BRAKING SYSTEMDISC BRAKE SYSTEM
ANTI BRAKING SYSTEM
(ABS)
Types Of Braking system

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Mechanical Braking System
 This braking system works with mechanical linkage between the brake pedal and
brake shoes to transmit pedal force to the brake shoes.’
 When the brake pedal is pressed, the cam turns by means of brake linkage. When
the cam turns, the shoe expands outwards against the drum.
 The brake lining rub against the drum and thus stop its motion.
 There are two types of mechanical braking system
1. Internal Expanding 2. External Contracting

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Working system of internal
expanding braking system
Internal expanding braking system
consist of brake linings are fixed at
outsides when brakes are applied
the cam is turned, the shoe with
brake lining are forced against the
Drum.
This Causes brake lining creates
friction between the rotating drum
and expanding shoes.
This force of friction opposes the
rotating drum, thereby will leads to
slowing down the vehicle.
When brake is released Retracting
springs brings the shoe back
towards its original position.

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The working system of external
braking system, when push rod is
operated by hand or foot operated
lever, then the lined brake drum is
fitted around the drum is tightened
to lock or slow down the drum.
When the brake is released the
return springs bring the band
brake back to its initial position.
The system remains air opened;
therefore dirt is being accumulated
between the rubbing surfaces,
which reduces the efficiency…
WORKINGOFEXTERNALCONTRACTINGBRAKINGSYSTEM

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Hydraullic Braking System
 Hydraulics is the use of a liquid under pressure to transfer force or motion, or to
increase an applied force.
 The pressure on a liquid is called HYRAULIC PRESSURE.
 And the brakes which are operated by means of hydraulic pressure are called
HYDRAULIC BRAKES.
 These brakes are based on the principle of Pascal’s law.

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PASCAL’S LAW
 The pressure exerted anywhere in a mass of confined liquid is
transmitted undiminished in all directions throughout the liquid.
 Applied in hydraulic lifts, hydraulic brakes etc.

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Working System
The brake pedal is connected to the master
cylinder by means of piston for application of
brake driver presses the brake pedal, which
moves the master cylinder.
In master cylinder pressure is instantly transferred
to all four wheels. The brakes shoe moves
against the brake drum to apply brakes.
When driver releases the brake pedal, the master
cylinder piston returns to its original position due
to return springs, dropping fluid pressure. Brake
shoe retracting spring pulls the brake shoe from
drum to their original position & brakes are
released.
ROLE OF MASTER CYLINDER:ROLE OF MASTER CYLINDER:
TO BUILD THE hydraulic pressure required to
operate the system.
To bleed or force air out of brake line & wheel
cylinder.
A to act reservoir to maintain a constant volume
of fluid in system
.

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ADVANTAGES OF HYDRAULIC BRAKES
 Equal braking effort to all the four wheels
 Less rate of wear (due to absence of joints compared to mechanical brakes)
 simple in construction :Mechanical joints, linkages & cam are eliminated.
 Force multiplication (or divisions) very easily just by changing the size of one piston
and cylinder relative to other.
DISADVANTAGES OF HYDRAULIC BRAKES
 Even slight leakage of air into the breaking system makes it useless.
 The brake shoes are liable to get ruined if the brake fluid leaks out.

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 Single-cylinders are the most basic type of
master cylinder, and are internally very
similar to a plastic medical syringe.
 The brake pedal lever pushes the plunger
(piston) inside the cylinder, which shoves
fluid through the lines and into the slave
cylinders.
 When the brake pedal is released, a spring
inside of the cylinder pushes the plunger
back to its original position. Negative
pressure pulls the brake fluid into the
cylinder from the lines and from the brake
fluid reservoir.
 Many race car builders prefer to use a pair
of single cylinders instead of a single
tandem cylinder to control front/rear brake
pressure bias.
Single-Cylinder

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Ported Tandem Cylinder
A tandem cylinder is two pistons in one. The primary piston is connected
to the brake pedal.
When the brake pedal is pressed, the piston pushes on a spring
connected to the back of the secondary piston.
Once that spring compresses fully, the secondary piston starts to push
fluid through its own dedicated system.
The reservoir inlet port allows fluid to flow behind the pistons to keep
pressure even on both sides.
When the brake pedal is released, spring pressure pushes the pistons
back and a small compensating port from the brake fluid reservoir
introduces extra fluid into the chamber.
The compensating port is necessary to speed up brake release, which
would otherwise be inhibited by the speed of the fluid moving backward
through the lines.
The main function of tandem master cylinder is that in case of any leak in
the fluid line, the braking will be possible with the help of separate fluid
line.

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Illustration 1, if a leak develops in the front brake system, Piston 1 will move forward
until it contacts Piston 2. Force from the brake pedal will be transmitted mechanically
through Piston 1 to Piston 2. Although overall braking performance will be severely
compromised, the rear brakes will still be functional provided sufficient pedal travel is
available. The pedal will need to travel further than normal to fully engage the rear
brakes. Also, it should be appreciated that trying to stop quickly with just the rear
brakes is very tricky because the rear tires will easily reach the point of lock-up. As
the car is slowing, weight transfers forward and the rear wheels lose some of their
much needed traction.

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Illustration 2 If a leak develops in the rear brake system, Piston 2 will move
forward until it contacts the closed end of the master cylinder housing. Once
Piston 2 becomes stationary, pressurization of fluid between the two pistons will
apply the front brakes. Although overall braking performance will be significantly
compromised, the front brakes will still be functional provided sufficient pedal
travel is available. The pedal will need to travel further than normal to fully
engage the front brakes. (Frankly, some inattentive or inexperienced drivers have
been known to continue driving with non-functional rear brakes, despite longer
pedal travel and longer stopping distances. For this reason, newer cars are fitted
with brake failure warning lights.)

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Portless Master Cylinder
First introduced on the Toyota MR2,
portless master cylinders offer quicker
brake release than standard designs that
utilize a compensating port. Portless
cylinders utilize a valve assembly in the
pistons that opens to equalize pressure
when the brakes are released. This allows
the brake cylinder to do without the
compensating port, which is more
restrictive to fluid flow and bleeds pressure
from the brake system under initial
application. The quicker-responding
portless cylinder works better with anti-lock
braking (ABS) systems, which use rapid
pressure modulations to adjust braking
force

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Pneumatic Braking System

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CONSTRUCTONCONSTRUCTON
Pneumatic BRAKES ARE OPERATED BY MEAns of Air pressure engine to air and
stores in air reservoir.the compressed air enters in wheel cylinder to push
diaphragm
The pneumatic braking system consists as :
Air compressor, unloader valve, resevoir, brake valve, brake chamber ,quick
release valve, Relay valve etc.
Air Compresor
• Its composes of generally Build the air pressureby driven of engine.
UNLOADER VALVE:
• ITS IS DEVICE MAINTAIN CONSTANT PRESSURE IN RESERVOIR.the excess of pressure is
safely removed.
Reservoir:
• it’s a tank in which high pressure air is stored
Brake Valve:
• its is located between air reservoir and brake cylinder
RELAY VALVE:
IT IS VALVE KEPT IN BETWEEN BRAKE CHAMBER & AIR CHAMBER FOR CONTROLLING THE
AIR CHAMBER

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Disc Type Brake
In a disc brake, the fluid from the master cylinder is forced into a calliper where
it presses against a piston.
The piston in turn squeezes two brake pads against the disc (rotor), which is
attached to wheel, forcing it to slow down or stop.
There are four main parts of disc brake :
1.Mounting Bracket.
2.Rotor.
3.Caliper.
4.Pads.

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Mounting Brackets :
Mounting brackets are used to hold the caliper in a place.
Rotors :
The brake disc (or rotor) is the rotating part of a wheel's disc brake assembly,
against which the brake pads are applied.
The material is typically gray iron, a form of cast iron.
The weight and power of the vehicle determines the need for ventilated discs.
There are two types of rotors:
1.Vented Rotor:
The Vented Rotor have Fins in the spaces between their machined surface. This
design helps to dissipate the generated heat and is commonly used on the more-
heavily-loaded front discs.
2. Non Vented Rotor:
It is basically a solid disc without any Colling fins. They are mostly used in smaller
vehicles.

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1.Vented Rotor: 2. Non Vented Rotor:

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Working of Floating calliper
A calliper bracket is solidly mounted and the
calliper itself within that bracket isn't solidly
mounted so it can slide left and right via pins
and bushings on the bracket.
 A piston on the inner side of the disc pushes
that brake pad as if to move the disc but
because the disc can't slide, the force pulls the
sliding calliper with another brake pad unto
the other side of the disc.
 The advantages of the floating calliper is
that its cheaper and lighter than the fixed
calliper as it uses less parts and is more
compact.

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Working of Fixed calliper
The entire calliper is solidly mounted and
there is a piston or pistons on both sides of the
disc. The pistons push the two brake pads onto
both sides of the disc.
 The fixed calliper use multiple pistons
sorted in pairs with two, four and six being the
usual number of pistons as opposed to the one
piston in the sliding type.
The fixed calliper can apply more squeezing
power and apply that power more evenly
during braking as force is directly applied to
both sides even if its a two piston brake.
 Fixed callipers also provide a better feel
through the brake pedal whenever the driver
applies the brake which is preferable for luxury
and performance vehicles.

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BRAKE FLUIDS
 One of the important characteristics of brake fluid is its BOILING POINT.
 Hydraulic systems rely on incompressible fluid to transmit force.
 Liquids are generally incompressible while gases are compressible.
 If the break fluid boils (becomes a gas), it will loose most of its ability to
transmit force. This may partially or completely disable the brakes.
 As a DOT 3 or DOT 4 brake fluid absorbs water, its boiling point decreases. It
can absorb water from air, that is why we should avoid opening the car’s
brake fluid reservoir and the container of the brake fluid should be tightly
sealed.

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