ABS - Antilock Braking System
#1

anti-lock braking system, or ABS is a safety system which prevents the wheels on a motor vehicle from locking up (or ceasing to rotate) while braking.A rotating road wheel allows the driver to maintain steering control under heavy braking by preventing a skid and allowing the wheel to continue interacting tractively with the road surface as directed by driver steering inputs. While ABS offers improved vehicle control, and may decrease stopping distances on dry and especially slippery surfaces, it can also increase braking distance on loose surfaces such as snow and gravel , anti-lock braking systems have evolved considerably. Recent 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 brakeforce distribution (EBD), traction control system, emergency brake assist, or electronic stability control.

ABS is composed of a central electronic control unit (ECU), four wheel speed sensors ” one for each wheel ” and two or more hydraulic valves within the brake hydraulics. The ECU constantly monitors the rotational speed of each wheel, and when it detects a wheel rotating significantly slower than the others ” a condition indicative of impending wheel lock , it actuates the valves to reduce hydraulic pressure to the brake at the affected wheel, thus reducing the braking force on that wheel. The wheel then turns faster; when the ECU detects it is turning significantly faster than the others, brake hydraulic pressure to the wheel is increased so the braking force is reapplied and the wheel slows. This process is repeated continuously, and can be detected by the driver via brake pedal pulsation. A typical anti-lock system can apply and release braking pressure up to 20 times a second


read more about Anti-lock_braking_system http://en.wikipediawiki/Anti-lock_braking_system
http://autorepair.aboutod/glossary/a/def_ABS.htm
http://auto.howstuffworksauto-parts/brakes/brake-types/anti-lock-brake.htm

The ECU is programmed to disregard differences in wheel rotative speed below a critical threshold, because when the car is turning, the two wheels towards the center of the curve turn slower than the outer two. For this same reason, a differential is used in virtually all roadgoing vehicles.

If a fault develops in any part of the ABS, a warning light will usually be illuminated on the vehicle instrument panel, and the ABS will be disabled until the fault is rectified.
Reply
#2
[attachment=9936]
Anti Lock Braking System (ABS)
Introduction

 Wheel lockup during braking causes skidding which in turn cause a loss of traction and vehicle control
 This reduces the steering ability to change direction. So the car slides out of control
 With ABS system, the driver can brake hard, take the evasive action and still be in control of the vehicle in any road condition at any speed and under any load
Fundamentals of ABS
 Anti-lock brake systems prevent brakes from locking during braking
 On slippery roadways the wheel approach lock up, ABS brakes at this time takes over
 ABS brakes modulates brake line pressure and, hence, braking force
 Car with and without ABS
 Tire Characteristics
 Friction-Slip Curve
ABS Design Concept
 Retention of vehicle stability and steering ability
 Minimum reaction into steering wheel
 ABS must utilize available tire-road friction optimally
 ABS must adapt quickly to changes in tire-road friction levels.
 ABS must minimize the yaw moment
 ABS must provide stable braking while turning.
 ABS is not a substitute for poor brake balance
 ABS malfunctioning must be communicated with the driver
Abs Control Concept
The control of the different brake systems can be accomplished in following three manners:
o Single-wheel control
o Select-low control
o Select-high control
Schematic Diagram of ABS
Types of ABS
 Vacuum-powered systems
 Separate ABS systems
 Integrated ABS systems
Vacuum-powered ABS systems
 Vacuum powered ABS systems are not used in the modern vehicles
 In 1983, Chrysler and Mitsubishi used vacuum as the power source
 It consists of a pressure control section, a vacuum powered pressure drive unit, and solenoid valve
Separate ABS systems
 Since the reintroduction of ABS systems between the late ‘70s and mid-‘80s both separate and integrated systems have been used.
 In 1978 the separate ABS 2S design manufactured by Bosch and was the first anti-lock brake system to go into mass production with Mercedes Benz automobiles
Integrated ABS system
 Teves, in 1985 was the first company to introduce a compact integrated ABS system
ABS System Components
 Wheel speed sensors
 Electronic Control Unit (ECU)
 Hydraulic modulator
 Electric circuit
Wheel Speed Sensor
 The wheel speed sensors signal the wheel speed to the ECU
 ECU and Hydraulic Modulator
 The ECU receives, amplifies and filters sensors signals, as well as measures and differentiates speeds
 The hydraulic modulator converts the ECU commands for pressure modulation in the wheel brakes by use of solenoid valves
In-Use Factors and Operation of ABS Systems
 Brake Fluid
 Tire Size
 Brake Fluid Level
Reply
#3
[attachment=11009]
ANTI-LOCK BRAKES
ABS, (Anti-Lock brake system)

 ABS allows the driver to maintain steering control of the vehicle while in hard braking situations .
ANTI-LOCK BRAKES
 Computerized ABS is designed to keep the wheels from locking as the brakes are applied.
 A locked wheel provides very little or no directional control.
 The following slides show the common ABS components.
 Some components are part of both the conventional and ABS system.
 When operating a vehicle with ABS never pump the brakes.
 Doing so will make the ABS system ineffective.
Always apply firm pressure.
 Drivers may experience a pulsation in the brake pedal, or pedal kick back during an ABS stop. This is normal and not to be confused with a conventional brake pedal pulsation
 Major components of the anti-lock brake system consist of a
• Brake control module,
• Solenoid valve assembly,
• Speed sensor's
• Wiring, and the amber ABS brake warning light.
Brake Control Module:
 The brake control module is a compute that receives information from the speed sensor and compares it to the speed of other wheels.
 When one wheel is approaching lock-up pressure can be vented allowing the wheel nearing lock-up to speed up.
 If a wheel is to fast pressure can be increased to slow down the wheel.
 If both wheel are approximately the same speed the brake control module can enter a pressure hold mode of operation.
Solenoid Valve Assembly:
Is a pair of valves that can:
A. Increase pressure
B. Hold pressure steady
C. Decrease pressure
 ABS system can maintain extremely high static pressure and must be disabled before attempting repairs.
 Normally pumping brake 20-30 times will release pressure.
 ABS brake system are
• Integrated
• Nonintegrated
 An integrated system has the master cylinder and control valve assembly made together.
 A nonintegrated has the master cylinder and control valve assembly made separate.
 ABS operates using the same hydraulic principal as conventional brakes.
 ABS system only operates when wheel lock-up is emanate.
 A bussing noise and bakes pedal vibration is normal during ABS operation.
 To determine if wheel lock-up is about to occur vehicles a wheel speed sensor.
 There 3 ABS configurations
• 1. channel normally RWAL (rear wheel anti-lock)
• In a one channel RWAL system the rear wheels are controlled together
• ANTI-LOCK BRAKES
 ABS brakes are either
• 1. Channel
• 3 Channel
• 4 Channel
 1 channel ABS system controls the rear wheel together.
 A 1 channel system only has 1 speed sensor and control valve assembly.
 A three (3) channel ABS system control the rear wheel together and the front independently.
 Three channel ABS system have 3 speed sensor and one (1) control module
 Wheel Slippage, is the wheel speed in relation to vehicle speed.
 If vehicle speed is faster than the wheel speed slippage is negative. And the wheel may become lock-up
 If vehicle speed is slower than wheel speed. Wheel slippage is positive.
 Positive wheel slippage occurs when a wheel is spinning.
 NOTE: Late model vehicles use the same ABS components with traction control. Traction control prevent a vehicle from spinning out of control.
 The best braking action occurs at between 10-20%.
 If vehicle speed and wheel speed is the same wheel slippage is 0%
 A lock-up wheel will have a wheel slippage of 100%
 In a diagonally split system brake system the left front and right rear brakes are controlled together.
 Diagonally split systems offer an added safety value.
 When diagnosing an ABS concern always
• 1. Talk with customer/ owner, to deterring if the ABS at fault or a basic brake system concern
• 2. Always check the basic brake system 1st.
• 3. Check for proper tire size
• 4. Check for damage sensor and reluctor rings.
• 5. Check brake light operation
• 6. Check for diagnostic trouble codes
ABS QUIZ
 1. Technician A says, That ABS works only in a panic situation. Technician B says ABS works when wheel lock-up is determine. Who is correct?
• A. Technician A only B. Technician B only
• C. Neither A nor B D. Both A and B
 2. Technician A says a lock-up wheel provides no directional control. Technician B says a lock-up wheel provides a shorter stopping distance. Who is correct?
 A. Technician A only B. Technician B only
 C. Both A and B D. Neither A nor B
 3. What component is used to determine vehicle speed?
• A. Throttle position sensor
• B. Mass air flow meter
• C. Oxygen sensor
• D. Wheel speed sensor
 4. Technician A says when operating a vehicle with ABS brakes you should pump the brake. Technician B says to hold firm when applying brakes. Who is correct?
 A. Technician A only B. Technician B only
 C. Both A and B D. Neither A nor B
 ABS QUIZ
 5. What type brake fluid should never be used with an ABS system?
• A. DOT 3
• B. DOT 4
• C. DOT 5
• D. All the above can be used
Reply
#4
anti-lock braking system, or ABS is a safety system which prevents the wheels on a motor vehicle from locking up (or ceasing to rotate) while braking.A rotating road wheel allows the driver to maintain steering control under heavy braking by preventing a skid and allowing the wheel to continue interacting tractively with the road surface as directed by driver steering inputs. While ABS offers improved vehicle control, and may decrease stopping distances on dry and especially slippery surfaces, it can also increase braking distance on loose surfaces such as snow and gravel , anti-lock braking systems have evolved considerably. Recent 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 brakeforce distribution (EBD), traction control system, emergency brake assist, or electronic stability control.
Reply
#5
Prepared by
JYOTI RANJAN NAYAK

[attachment=11724]
Introduction
An anti-lock braking system (ABS) is a safety system on motor vehicles which prevents the wheels from locking while braking.
A rotating road wheel allows the driver to maintain steering control under heavy braking, by preventing a locked wheel or skid, and allowing the wheel to continue to forward roll and create lateral control, as directed by driver steering inputs. Disadvantages of the system include increased braking distances under some limited circumstances (snow, gravel, "soft" surfaces), and the creation of a "false sense of security" among drivers who do not understand the operation, and limitations of ABS.
History
• Anti-lock braking systems were first developed for aircraft in 1929, by the French automobile and aircraft pioneer, Gabriel Voisin, as threshold braking an airplane is nearly impossible.
• An early system was Dunlop's Maxaret system, introduced in the 1950s and still in use on some aircraft models.
• A fully mechanical system saw limited automobile use in the 1960s in the Ferguson P99 racing car, the Jensen FF and the experimental all wheel drive Ford Zodiac, but saw no further use; the system proved expensive and, in automobile use, somewhat unreliable.
• However, a limited form of anti-lock braking, utilizing a valve which could adjust front to rear brake force distribution when a wheel locked, was fitted to the 1964 Austin 1800.
• Chrysler, together with the Bendix Corporation, introduced a crude, limited production ABS system on the 1971 Imperial. Called "Sure Brake", it was available for several years, and had a satisfactory performance and reliability record.
• Ford also introduced anti lock brakes on the Lincoln Continental Mark III and the Ford LTD station wagon, called "Sure Trak" in 1975.
• The German firms Bosch and Mercedes-Benz had been co-developing anti-lock braking technology since the 1930s, and introduced the first completely electronic 4-wheel multi-channel ABS system in trucks and the Mercedes-Benz S-Class in 1978.
• ABS Systems based on this more modern Mercedes design were later introduced on other cars and motorcycles. General Motors introduced the "Trackmaster" ABS on their Cadillac models in 1971 as an option that was operational on the rear wheels for RWD models.
In 1988 BMW became the world's first motorcycle manufacturer to introduce an electronic/hydraulic ABS system, this on their BMW K100.
• In 1992 Honda launched its first ABS system, this on the ST1100 Pan European.
• In 1997 Suzuki launched its GSF1200SA (Bandit) with ABS
• Today ABS has become a standard equipment even for small cars
Theory
When the car brakes (normally), the momentum of the car must be reduced, so a backwards force needs to be transmitted to the car. This is achieved by the wheels exerting a forward force on the street which lies below the threshold of maximum static sliding friction. The wheels keep sticking to the road because of this friction.
If the driver brakes very hard (or accelerates extremely) it can occur that the maximum static friction is surpassed and the wheels lose their grip and begin sliding (or spinning). In this case the dynamic sliding friction (which is less than the maximum static friction) takes over
The amount of traction which can be obtained for an auto tire is determined by the coefficient of static friction between the tire and the road. If the wheel is locked and sliding, the force of friction is determined by the coefficient of kinetic friction and is usually significantly less. A tire that is just on the verge of slipping (10 to 20% slippage) produces more friction with respect to the road than one which is locked and skidding (100% slippage). Once traction is lost, friction is reduced, the tire skids and the vehicle takes longer to stop. So locked wheels are less effective in stopping on a road
But in gravel, sand and deep snow, locked wheels dig in and stop the vehicle more quickly. A locked tire allows a small wedge of snow to build up ahead of it which allows it to stop in a somewhat shorter distance than a rolling tire. That is why some vehicles have an on/off switch for deactivating the antilock system when driving on snow.
So, antilock brakes do not necessarily reduce the stopping distance, and in fact may actually increase stopping slightly on dry pavement. But on wet or slick pavement, antilock brakes may reduce the stopping distance up to 25% or more, which could be the difference between a safe stop and an accident
But what ABS provides is Directional stability which is very crucial.
Directional stability also depends on traction. As long as a tire does not slip, it will roll only in the direction it turns. But once it skids, it has about as much directional stability as a hockey puck on ice because, regardless of the angle of the front wheels, the vehicle continues to skid in whatever direction its momentum sends it until either the driver releases the brakes. By minimizing the loss of traction, antilock braking helps maintain directional stability and steering control

Reply
#6
[attachment=12955]
ANTI LOCKING BRAKES
Introduction

An anti-lock braking system (ABS, from German: Antiblockiersystem) is a safety system that allows the wheels on a motor vehicle to continue interacting with the road surface as directed by driver steering inputs while braking, preventing the wheels from locking up (that is, ceasing rotation) and therefore avoiding skidding.
An ABS generally offers improved vehicle control and decreases stopping distances on dry and slippery surfaces for many drivers; however, on loose surfaces like gravel or snow-covered pavement, an ABS can significantly increase braking distance, although still improving vehicle control.
Since initial widespread use in production cars, anti-lock braking systems have evolved considerably. Recent 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 system, emergency brake assist, or electronic stability control (ESC).
The theory behind anti-lock brakes is simple. A skidding wheel (where the tire contact patch is sliding relative to the road) has less traction than a non-skidding wheel. If you have been stuck on ice, you know that if your wheels are spinning you have no traction. This is because the contact patch is sliding relative to the ice (see Brakes: How Friction Works for more). By keeping the wheels from skidding while you slow down, anti-lock brakes benefit you in two ways: You'll stop faster, and you'll be able to steer while you stop.
The system known as anti-lock brakes helps drivers to have better control of a vehicle in some road conditions where braking may be necessary. In vehicles without anti-lock brake systems, drivers who encounter slippery conditions may have to pump brakes to make sure they do not spin out of control because of locked up wheels. ABS systems work to coordinate wheel activity with a sensor on each wheel that regulates brake pressure as necessary, so that all wheels are operating in a similar speed range. Here are some of the main benefits of an ABS system.
Despite the fact that anti-lock brakes are proven to be a safety featurein most situations, and insurers consider them to significantly lower risk for a vehicle, not all drivers are sold on this option for a car or truck. Here are some of the down sides that drivers claim about this kind of brake system
HISTORY
1.1Early systems

The ABS was first developed for aircraft use in 1929 by the French automobile and aircraft pioneer, GABRIEL VOISIN, as threshold braking on airplanes is nearly impossible. An early system was DUNLOP'S MAXARET system, which was introduced in the 1950s and is still in use on some aircraft models.[2] These systems use a flywheel and valve attached to a hydraulic line that feeds the brake cylinders. The flywheel is attached to a drum that runs at the same speed as the wheel. In normal braking, the drum and flywheel should spin at the same speed. However, if a wheel were to slow down, then the drum would do the same, leaving the flywheel spinning at a faster rate. This causes the valve to open, allowing a small amount of brake fluid to bypass the master cylinder into a local reservoir, lowering the pressure on the cylinder and releasing the brakes. The use of the drum and flywheel meant the valve only opened when the wheel was turning. In testing, a 30% improvement in braking performance was noted, because the pilots immediately applied full brakes instead of slowly increasing pressure in order to find the skid point. An additional benefit was the elimination of burned or burst tires.
In 1958, a Royal Enfield Super Meteor motorcycle was used by the Road Research Laboratory to test the MAXARET anti-lock brake. The experiments demonstrated that anti-lock brakes can be of great value to motorcycles, for which skidding is involved in a high proportion of accidents. Stopping distances were reduced in most of the tests compared with locked wheel braking, particularly on slippery surfaces, in which the improvement could be as much as 30 percent. Enfield's technical director at the time, Tony Wilson-Jones, saw little future in the system, however, and it was not put into production by the company.
One manufacturer‘s name is synonymous with the recent history of ABS. Bosch was the first manufacturer in the world to begin manufacturing ABS in series production in 1978 following a ten-year period of development. The first millionth ABS was produced eight years following production startup. By 1996 Bosch had supplied 25 million systems and the figure rose to more than 40 million in 1998.
The 50 millionth ABS unit rolled off the production line of Bosch`s IMMENSTADT (ALLGÄU) plant in Germany at the end of July. Every workday more than 40,000 of these electronic safety systems leave Bosch`s 17 production facilities located in Germany and abroad. This amounts to more than a third of all such systems produced around the globe today.
In 1999, Bosch-produced ABS systems will be fitted to 92% of the passenger cars produced in Germany, 67% of passenger cars in Western Europe, 74% in North America, 62% in Japan and 55% worldwide. In the beginning, ABS was mostly found in top-of-the range cars but by1999, up to 86% of all compact cars produced in Western Europe and up to 30 percent of even smaller cars were equipped with ABS
1.2Modern systems
Chrysler, together with the BENDIX Corporation, introduced a computerized, three-channel, four-sensor all-wheel ABS called "Sure Brake" for its 1971 Imperial. It was available for several years thereafter, functioned as intended, and proved reliable. In 1971, General Motors introduced the "TRACKMASTER" rear-wheel only ABS as an option on their Rear-wheel drive Cadillac models. In the same year, Nissan offered an EAL (Electro Anti-lock System) as an option on the Nissan President, which became Japan's first electronic ABS.
In 1988, BMW introduced the first motorcycle with an electronic-hydraulic ABS: the BMW K100. Honda followed suit in 1992 with the launch of its first motorcycle ABS on the ST1100 Pan European. In 2007, Suzuki launched its GSF1200SA (Bandit) with an ABS. In 2005, Harley-Davidson began offering ABS as an option for police bikes. In 2008, ABS became a factory-installed option on all Harley-Davidson Touring motorcycles and standard equipment on select models
In the early stage of ABS it had very few signals to control its behavior. It calculates the wheel speed and captures the vehicle speed by releasing breaks while wheel speed is 0 through the same speedometer. And it treats all 4 wheels the same way. This system worked fine in general road conditions yet there were identified problems. In the case of vehicle is driving down a hill, the vehicle speed will never be 0 while it release the break to capture it due the energy transformation from potential energy to kinetic energy. Hence there was no way to totally stop a vehicle which is driving down the hill by using break paddles. The problem were quickly solved using a simple logic that if wheel speed were less that certain level it will be locked by break till the driver releases the break paddle.
Additionally, if all four wheels are not in same road conations, this kind of break system yet result a skid. If two wheels are on snow and others on clean road, once the driver applies break it will turn the vehicle in an uncontrollable manner no matter it has ABS. Having the objective of solving this problem modern ABS systems collect data separately from all four wheels and apply ABS accordingly.
In traditional ABS systems collect the vehicle speed data from the same speedometer while uses to collect wheel speed data which is not always an accurate a mechanism. It always requires releasing the breaks and letting the wheels to spin to capture the relevant data. Modern ABS system are been designed to capture the vehicle speed using GPS data which could be identified as a proper mechanism, yet it could be less accurate. However, it doesn’t require releasing the break to capture vehicle speed.
Figure-1 ABS brakes on a BMW motorcycle
OPERATION OF ABS
The anti-lock brake controller is also known as the CAB (Controller Anti-lock Brake).
A typical ABS includes a central electronic control unit (ECU), four wheel speed sensors, and at least two hydraulic valves within the brake hydraulics. The ECU constantly monitors the rotational speed of each wheel; if it detects a wheel rotating significantly slower than the others, a condition indicative of impending wheel lock, it actuates the valves to reduce hydraulic pressure to the brake at the affected wheel, thus reducing the braking force on that wheel; the wheel then turns faster. Conversely, if the ECU detects a wheel turning significantly faster than the others, brake hydraulic pressure to the wheel is increased so the braking force is reapplied, slowing down the wheel. This process is repeated continuously and can be detected by the driver via brake pedal pulsation. Some anti-lock system can apply or release braking pressure 16 times per second.
The ECU is programmed to disregard differences in wheel relative speed below a critical threshold, because when the car is turning, the two wheels towards the center of the curve turn slower than the outer two. For this same reason, a differential is used in virtually all road going vehicles.
If a fault develops in any part of the ABS, a warning light will usually be illuminated on the vehicle instrument panel, and the ABS will be disabled until the fault is rectified.
The modern ABS applies individual brake pressure to all four wheels through a control system of hub-mounted sensors and a dedicated micro-controller. ABS is offered or comes standard on most road vehicles produced today and is the foundation for ESC systems, which are rapidly increasing in popularity due to the vast reduction in price of vehicle electronics. Over the year
Reply
#7
to get information about the topic HIGHWAY SPEED SENSING AND AUTOMATIC BREAKING SYSTEM full report ppt and related topic refer the page link bellow

http://studentbank.in/report-abs-antiloc...ing-system
http://studentbank.in/report-automatic-b...abs?page=3
http://studentbank.in/report-highway-spe...ing-system
Reply
#8


to get information about the topic "antilock bracking system" full report ppt and related topic refer the page link bellow

http://studentbank.in/report-abs-antiloc...e=threaded

http://studentbank.in/report-anti-lock-b...ode=linear
Reply

Important Note..!

If you are not satisfied with above reply ,..Please

ASK HERE

So that we will collect data for you and will made reply to the request....OR try below "QUICK REPLY" box to add a reply to this page
Popular Searches: antilock beaking system ppt, hiit training for abs, syntronic braking system, seminar report on abs ppt, electromagnetic actuator in abs for 2 wheeler pdf, low gloss abs system ppt, skidding,

[-]
Quick Reply
Message
Type your reply to this message here.

Image Verification
Please enter the text contained within the image into the text box below it. This process is used to prevent automated spam bots.
Image Verification
(case insensitive)

Possibly Related Threads...
Thread Author Replies Views Last Post
  pneumatic operated emergency braking system karthik hr 3 2,919 01-09-2015, 07:08 PM
Last Post: Guest
  anti lock braking system full report project report tiger 6 8,587 23-09-2014, 07:25 PM
Last Post: seminar report asees
  anti locking braking system full report seminar topics 6 7,495 15-01-2013, 12:11 PM
Last Post: seminar details
  Technician Guidelines for Antilock Braking Systems computer girl 0 1,229 07-06-2012, 01:07 PM
Last Post: computer girl
  Automotive Braking Systems seminar class 1 2,649 20-02-2012, 12:59 PM
Last Post: seminar paper
  automatic braking system ABS electronics seminars 9 15,115 14-02-2012, 01:14 PM
Last Post: seminar paper
  Regenerative braking seminar surveyer 2 5,147 06-02-2012, 10:42 AM
Last Post: seminar addict
  Vacuum Braking System computer science crazy 2 13,821 08-01-2011, 02:52 PM
Last Post: summer project pal
  EPM Braking:Electric pulse Magnetic Braking full report project topics 2 4,864 22-12-2010, 09:43 AM
Last Post: seminar surveyer
  Troubleshooting Antilock Braking computer science crazy 0 2,393 21-09-2008, 09:30 AM
Last Post: computer science crazy

Forum Jump: