46105597 braking system

8/2/2019 46105597 Braking System

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To study about various

types of braking system



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INTRODUCTION

Ø The system is purely mechanical means & is independent of the hydraulic system which controls the brake normally.

Ø A brake commonly referred to special braking system for adriver.

Ø The brake is also used as a parking brake to stop car fromrolling when it’s stopped & turned off because it’s a purelymechanical system rather then hydraulic one.

Ø It is an important part for a motor vehicle.

Ø The setup of brake is simple, a cables connect to the braking

mechanism in the rear wheels & attached to a pedal or levernear driver’s seat.

Ø In the most common type of braking system in passengervehicles that a lever located between the driver & passengerseat which can applied by either party highly useful if driver is

independent.



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How Brakes Work

Ø Brakes are a system installed in motor vehicles. Also known ase-brakes, hand brakes and parking brakes, the brakes are nowpowered by hydraulics and are independent of the servicebrakes used to slow and stop vehicles. There are state andfederal laws requiring brakes for motor vehicles.

Ø Most modern braking system have failsafe measures andwarning systems, such as on dash brake-warning lights andlow fluid sensors, the brake is most often used as a parkingbrake device.

Ø It is using it can save your life.



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Main components of

systemü Speed sensors

ü Pump

ü Valves

ü Controller

ü Master Cylinder

ü Brake Fluid

ü Brake Lines

ü Pressure Differential Valve

ü Combination Valve



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• Master Cylinder

MAIN

PARTS



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Brake Fluid

Ø Brake fluid is special oil that has specific properties. It isdesigned to withstand cold temperatures without thickeningas well as very high temperatures without boiling.

Ø If the brake fluid should boil, it will cause you to have aspongy pedal and the car will be hard to stop.

Ø Brake fluid must meet standards that are set by theDepartment of Transportation (DOT). The current standard isDOT-3, which has a boiling point of 460º F.

Ø The brake fluid reservoir is on top of the master cylinder. Mostcars today have a transparent reservoir so that you can see

the level without opening the cover. The brake fluid level willdrop slightly as the brake pads wear.

Ø This is a normal condition and no cause for concern. If thelevel drops noticeably over a short period of time or goesdown to about two thirds full, have your brakes checked as

soon as possible. Brake fluid must maintain a high boilingpoint. Exposure to air will cause the fluid to absorb moisture,


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Brake Lines

Ø The brake fluid travels from the master cylinder to the wheelsthrough a series of steel tubes and reinforced rubber hoses. Rubberhoses are used only in places that require flexibility, such as at thefront wheels, which move up and down as well as steer.

Ø The rest of the system uses non-corrosive seamless steel tubing

with special fittings at all attachment points.

Ø If a steel line requires a repair, the best procedure is to replace thecomplete line. If this is not practical, a line can be repaired usingspecial splice fittings that are made for brake system repair.

Ø

We must never use brass "compression" fittings or copper tubing torepair a brake system. They are dangerous and illegal.



Pressure Differential Valve

Ø This valve is usually mounted just below the master cylinder and isresponsible for turning the brake warning light on when it detects amalfunction.

Ø It measures the pressure from the two sections of the mastercylinder and compares them.

Ø Since it is mounted ahead of the proportioning or equalizer valve,the two pressures it detects should be equal. If it detects adifference, it means that there is probably a brake fluid leaksomewhere in the system.

Combination Valve

Ø The Combination valve is simply a proportioning valve and a

pressure differential valve that is combined into one unit.



Ø This invention relates to a hydraulic or air brake system forautomotive vehicles and the like and is useful for other similarhydraulic or fluid pressure systems, such as steering systemsand the like.

Ø An outstanding disadvantage of conventional vehicle hydraulic

brake systems is that if the master cylinder of the foot brakesystem fails, all four wheel brakes become inoperative.

Ø Such mechanical brake systems are rarely adjusted properlyso that either the right or left brake applies first, making thevehicle swerve and subject to danger, -- also mechanical

brakes do not bring present vehicles to a safe complete stop ina relatively short distance when the car is running at a highrate of speed.

Ø A still further object of the invention is to provide an hydraulicor air brake system which can be easily, quickly andinexpensively adapted to conventional hydraulic or air brakesystems in a minimum amount of time, with very little effort

Description



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SOME TYPES OF BREAK

v Brakes may be broadly described as using friction, pumping, orelectromagnetic. One brake may use several principles: forexample, a pump may pass fluid through an orifice to create

friction.

Ø Disk Brakes

Ø Drum Brakes

Ø Parking Brakes

Ø Anti-Lock Brakes

Ø Self-Adjusting Brakes



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Disc Brakes



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Drum Brakes



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Parking Brakes

Ø The parking brake system controls the rear brakes through aseries of steel cables that are connected to either a hand leveror a foot pedal.

Ø The idea is that the system is fully mechanical and completelybypasses the hydraulic system so that the vehicle can be

brought to a stop even if there is a total brake failure.

Ø On drum brakes, the cable pulls on a lever mounted in the rearbrake and is directly connected to the brake shoes. this hasthe effect of bypassing the wheel cylinder and controlling thebrakes directly.

Ø Disk brakes on the rear wheels add additional complication forparking brake systems. There are two main designs foradding a mechanical parking brake to rear disk brakes.

q Note: - Never leave your vehicle unattended withoutapplying the parking brakes or chocking the wheels.

Your vehicle might roll away and cause injury anddamage.



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Anti-Lock Brakes

Ø The most efficient braking pressure takes place just beforeeach wheel lock up. When you slam on the brakes in a panicstop and the wheels lock up, causing a screeching sound andleaving strips of rubber on the pavement, you do not stop thevehicle nearly as short as it is capable of stopping.

Ø In most cases, only the wheel that is locked will be pumped,while full braking pressure stays available to the otherwheels. This effect allows you to stop in the shortest amountof time while maintaining full steering control even if one ormore wheels are on ice.

Ø The system consists of an electronic control unit, a hydraulicactuator, and wheel speed sensors at each wheel. If thecontrol unit detects a malfunction in the system, it willilluminate an ABS warning light on the dash to let you knowthat there is a problem. If there is a problem, the anti-locksystem will not function but the brakes will otherwise function

normally.



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Anti-Lock Brake Diagram



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Self-Adjusting Brakes

Ø The single-piston floating-caliper disc brake is self-centeringand self-adjusting. The caliper is able to slide from side to sideso it will move to the center each time the brakes are applied.

Ø The parts of a self adjusting system should be clean and movefreely to insure that the brakes maintain their adjustment over

the life of the linings.Ø If the self adjusters stop working, you will notice that you will

have to step down further and further on the brake pedalbefore you feel the brakes begin to engage. Disk brakes areself adjusting by nature and do not require any type of mechanism.

Ø When a technician performs a brake job, aside from checkingthe return springs, he will also clean and lubricates the self adjusting parts where necessary.



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Details of Brake Operation

Ø During braking, the motor fields are connected across either themain traction generator or the supply and the motor armatures areconnected across either the brake grids or supply line. The rollinglocomotive wheels turn the motor armatures, and if the motor fieldsare now excited, the motors will act as generators.

Ø These are the brakes on the locomotive units only and do not applybrakes on any of the cars.

Ø The brake effectively slow the locomotives if operated alone, thistype of braking has only a minimal effect on a fully loaded train.

These brakes are used in train handling, standing or any time a

small brake level is needed on a train.Ø For permanent magnet motors, dynamic braking is easily achieved

by shorting the motor terminals, thus bringing the motor to a fastabrupt stop.



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Automatic EmergencyBraking (AEB)

Ø Automatic Emergency Braking (AEB) combines advancedDriver Assist Systems and Electronic Stability Control to slowthe vehicle and potentially mitigate the severity of an impactwhen a collision is unavoidable.

Ø AEB works with or without driver intervention by combining

data from forward-looking radar and video systems to providea complete, accurate and real-time image of the road ahead.AEB can utilize long-range radar (LRR) or mid-range radar(MRR) in combination with a scalable video camera.

Ø If a driver's steering and braking intervention is not enough to

avoid a collision, autonomous emergency braking withmaximum brake pressure will be applied to help mitigate theimpact. This final action is realized as full ABS braking, and itensures maximum speed reduction.

Ø Next, brake pressure is applied automatically, providingmaximum brake boost immediately once the driver doesengage the brakes.



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Dangers of Break

Ø When the drums are heated by hard braking, the diameter of the drum increases slightly due to thermal expansion, thismeans the brakes shoes have to move farther and the brakepedal has to be depressed further.

Ø The properties of the friction material can change if heated,

resulting in less friction. This is usually only temporary and thematerial regains its efficiency when cooled, but if the surfaceoverheats to the point where it becomes glazed the reductionin braking efficiency is more permanent. Surface glazing canbe worn away with further use of the brakes, but that takestime.

Ø Drum brakes can be grabby if the drum surface gets light rustor if the brake is cold and damp, giving the pad materialgreater friction. Grabbing can be so severe that the tires skidand continue to skid even when the pedal is released.



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When Brakes Fail

Ø Now onto the big question: Is using the brake safe when thevehicle fail to control? Yes and no. Pulling the brake leverquickly will cause the vehicle to fishtail, lock up or skid,essentially removing control of the vehicle from the driver. Butif you're ever in the highly unlikely but extremely serioussituation of having your service brakes fail to function, try tostay calm and pull the emergency brake lever up slow andsteady, bringing the vehicle to a longer but more controlledstop.

Ø

Stopping a car in a hurry on a slippery road can be verychallenging. Anti-lock braking systems (ABS) take a lot of thechallenge out of this sometimes nerve-wracking event. In fact,on slippery surfaces, even professional drivers can't stop asquickly without ABS as an average driver can with ABS.



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THANKS

46105597 braking system

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