![Absbrakes](https://upload.wikimedia.org/wikipedia/commons/1/12/Absbrakes.jpg)
An anti-lock braking system (ABS) is a
safety
Safety is the state of being "safe", the condition of being protected from harm or other danger. Safety can also refer to risk management, the control of recognized hazards in order to achieve an acceptable level of risk.
Meanings
There are ...
anti-
skid
__NOTOC__
Skid or Skids may refer to:
* Skid, a type of pallet
* Skid (aerodynamics), an outward side-slip in an aircraft turn
* Skid (automobile), an automobile handling condition where one or more tires are slipping relative to the road
* Ski ...
braking
A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction.
Background ...
system used on
aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...
and on land
vehicles
A vehicle (from la, vehiculum) is a machine that transports people or cargo. Vehicles include wagons, bicycles, motor vehicles (motorcycles, cars, trucks, buses, mobility scooters for disabled people), railed vehicles (trains, trams), wate ...
, such as
car
A car or automobile is a motor vehicle with wheels. Most definitions of ''cars'' say that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people instead of goods.
The year 1886 is regarded as ...
s,
motorcycle
A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle steered by a handlebar. Motorcycle design varies greatly to suit a range of different purposes: long-distance travel, commuting, cruising ...
s,
truck
A truck or lorry is a motor vehicle designed to transport cargo, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construction ...
s, and
bus
A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a road vehicle that carries significantly more passengers than an average car or van. It is most commonly used in public transport, but is also in use for cha ...
es. ABS operates by preventing the
wheel
A wheel is a circular component that is intended to rotate on an axle Bearing (mechanical), bearing. The wheel is one of the key components of the wheel and axle which is one of the Simple machine, six simple machines. Wheels, in conjunction wi ...
s from locking up during braking, thereby maintaining
tractive contact with the road surface and allowing the driver to maintain more control over the vehicle.
ABS is an automated system that uses the principles of
threshold braking
Threshold braking or limit braking is a driving technique most commonly used in motor racing, but also practiced in road vehicles to slow a vehicle at the maximum rate using the brakes.
The technique involves the driver controlling the brake peda ...
and
cadence braking
Cadence braking or stutter braking is a driving technique that involves pumping the brake pedal and is used to allow a car to both steer and brake on a slippery surface. It is used to effect an emergency stop where traction is limited to reduce the ...
, techniques which were once practiced by skillful drivers before ABS was widespread. ABS operates at a much faster rate and more effectively than most drivers could manage. Although ABS generally offers improved vehicle control and decreases stopping distances on dry and some slippery surfaces, on loose gravel or snow-covered surfaces ABS may significantly increase
braking distance
Braking distance refers to the distance a vehicle will travel from the point when its brakes are fully applied to when it comes to a complete stop. It is primarily affected by the original speed of the vehicle and the coefficient of friction be ...
, while still improving steering control.
Since ABS was introduced in production vehicles, such systems have become increasingly sophisticated and effective. Modern versions may not only prevent wheel lock under braking, but may also alter the front-to-rear
brake bias The brake balance or brake bias of a vehicle is the distribution of brake force at the front and rear tires, and may be given as the percentage distributed to the front brakes (e.g. 52%) or as the ratio of front and rear percentages (e.g. 52/48). Th ...
. This latter function, depending on its specific capabilities and implementation, is known variously as
electronic brakeforce distribution
Electronic brakeforce distribution (EBD or EBFD) or electronic brakeforce limitation (EBL) is an automobile brake technology that automatically varies the amount of force applied to each of a vehicle's wheels, based on road conditions, speed, lo ...
,
traction control system
A traction control system (TCS), also known as ASR (from german: Antriebsschlupfregelung, lit=drive slippage regulation), is typically (but not necessarily) a secondary function of the electronic stability control (ESC) on production motor vehicle ...
, emergency
brake assist
Brake assist (BA or BAS) or emergency brake assist (EBA) is a term for an automobile braking technology that increases braking pressure in an emergency. The first application was developed jointly by Daimler-Benz and TRW/LucasVarity. Research c ...
, or
electronic stability control
Electronic stability control (ESC), also referred to as electronic stability program (ESP) or dynamic stability control (DSC), is a computerized technology that improves a vehicle's stability by detecting and reducing loss of traction ( skiddi ...
(ESC).
History
Early systems
The concept for ABS predates the modern systems that were introduced in the 1950s. In 1908, for example, J.E. Francis introduced his 'Slip Prevention Regulator for Rail Vehicles'.
In 1920 the French
automobile
A car or automobile is a motor vehicle with Wheel, wheels. Most definitions of ''cars'' say that they run primarily on roads, Car seat, seat one to eight people, have four wheels, and mainly transport private transport#Personal transport, pe ...
and aircraft pioneer
Gabriel Voisin
Gabriel Voisin (5 February 1880 – 25 December 1973) was a French aviation pioneer and the creator of Europe's first manned, engine-powered, heavier-than-air aircraft capable of a sustained (1 km), circular, controlled flight, which was made ...
experimented with systems that modulated the hydraulic braking pressure on his aircraft brakes to reduce the risk of tire slippage, as threshold braking on aircraft is nearly impossible. These systems used a
flywheel
A flywheel is a mechanical device which uses the conservation of angular momentum to store rotational energy; a form of kinetic energy proportional to the product of its moment of inertia and the square of its rotational speed. In particular, ass ...
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, when a wheel slows 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.
The first proper recognition of the ABS system came later with the German engineer Karl Wässel, whose system for modulating braking power was officially
patent
A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A p ...
ed in 1928. Wässel, however, never developed a working product and neither did
Robert Bosch
Robert Bosch (23 September 1861 – 12 March 1942) was a German industrialist, engineer and inventor, founder of Robert Bosch GmbH.
Biography
Bosch was born in Albeck, a village to the northeast of Ulm in southern Germany as the eleventh of ...
who produced a similar patent eight years later.
By the early 1950s, the
Dunlop Maxaret
Dunlop's Maxaret was the first anti-lock braking system (ABS) to be widely used. Introduced in the early 1950s, Maxaret was rapidly taken up in the aviation world, after testing found a 30% reduction in stopping distances, and the elimination of ...
anti-skid system was in widespread aviation use in the UK, with aircraft such as the
Avro Vulcan
The Avro Vulcan (later Hawker Siddeley Vulcan from July 1963) is a jet-powered, tailless, delta-wing, high-altitude, strategic bomber, which was operated by the Royal Air Force (RAF) from 1956 until 1984. Aircraft manufacturer A.V. Roe and ...
and
Handley Page Victor
The Handley Page Victor is a British jet-powered strategic bomber developed and produced by Handley Page during the Cold War. It was the third and final '' V bomber'' to be operated by the Royal Air Force (RAF), the other two being the Avro ...
,
Vickers Viscount
The Vickers Viscount is a British medium-range turboprop airliner first flown in 1948 by Vickers-Armstrongs. A design requirement from the Brabazon Committee, it entered service in 1953 and was the first turboprop-powered airliner.
The Visc ...
,
Vickers Valiant
The Vickers Valiant was a British high-altitude jet bomber designed to carry nuclear weapons, and in the 1950s and 1960s was part of the Royal Air Force's "V bomber" strategic deterrent force. It was developed by Vickers-Armstrongs in response ...
,
English Electric Lightning
The English Electric Lightning is a British fighter aircraft that served as an interceptor during the 1960s, the 1970s and into the late 1980s. It was capable of a top speed of above Mach 2. The Lightning was designed, developed, and manufa ...
,
de Havilland Comet 2c,
de Havilland Sea Vixen
The de Havilland DH.110 Sea Vixen is a British twin-engine, twin boom-tailed, two-seat, carrier-based fleet air-defence fighter flown by the Royal Navy's Fleet Air Arm during the 1950s through to the early 1970s. The Sea Vixen was designed by ...
, and later aircraft, such as the
Vickers VC10
The Vickers VC10 is a mid-sized, narrow-body long-range British jet airliner designed and built by Vickers-Armstrongs (Aircraft) Ltd and first flown at Brooklands, Surrey, in 1962. The airliner was designed to operate on long-distance route ...
,
Hawker Siddeley Trident
The Hawker Siddeley HS-121 Trident (originally the de Havilland DH.121 and briefly the Airco DH.121) is a British airliner produced by Hawker Siddeley.
In 1957, de Havilland proposed its DH.121 trijet design to a British European Airways (B ...
,
Hawker Siddeley 125,
Hawker Siddeley HS 748
The Hawker Siddeley HS 748 is a medium-sized turboprop airliner originally designed and initially produced by the British aircraft manufacturer Avro. It was the last aircraft to be developed by Avro prior to its absorption by Hawker Siddeley.
...
and derived
British Aerospace ATP
The British Aerospace ATP (Advanced Turbo-Prop) is an airliner designed and produced by British Aerospace. It was an evolution of the Hawker Siddeley HS 748, a fairly successful feederliner of the 1960s.
The ATP was developed during the 1980 ...
, and
BAC One-Eleven
The BAC One-Eleven (or BAC-111/BAC 1-11) was an early jet airliner produced by the British Aircraft Corporation (BAC).
Originally conceived by Hunting Aircraft as a 30-seat jet, before its merger into BAC in 1960, it was launched as an 80-se ...
, and the Dutch
Fokker F27 Friendship
The Fokker F27 Friendship is a turboprop airliner developed and manufactured by the Dutch aircraft manufacturer Fokker. It is the most numerous post-war aircraft manufactured in the Netherlands; the F27 was also one of the most successful Europe ...
(which unusually had a Dunlop high pressure (200 Bar) pneumatic system in lieu of hydraulics for braking, nose wheel steering and landing gear retraction), being fitted with Maxaret as standard. Maxaret, while reducing braking distances by up to 30% in icy or wet conditions, also increased tire life, and had the additional advantage of allowing take-offs and landings in conditions that would preclude flying at all in non-Maxaret equipped aircraft.
In 1958, a
Royal Enfield Super Meteor
The Super Meteor was a British motorcycle made by Royal Enfield for export to the US between 1952 and 1962, when the Super Meteor was replaced by the 736 cc Royal Enfield Interceptor.
Development
In 1953, the US export market led Royal Enf ...
motorcycle
A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle steered by a handlebar. Motorcycle design varies greatly to suit a range of different purposes: long-distance travel, commuting, cruising ...
was used by the
Road Research Laboratory
TRL Limited, trading as TRL (formerly Transport Research Laboratory) is an independent private company offering a transport consultancy and research service to the public and private sector. Originally established in 1933 by the UK Government a ...
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%. 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.
A fully-mechanical system saw limited automobile use in the 1960s in the
Ferguson P99
The Ferguson P99 was a four-wheel drive Grand Prix car built by Ferguson Research Ltd. It was raced on behalf of the company by the Rob Walker Racing Team. Officially named as Ferguson Climax, it derived its P99 name from its Harry Ferguson Resea ...
racing car, the
Jensen FF
The Jensen FF is a four-wheel drive grand tourer produced by British car manufacturer Jensen Motors between 1966 and 1971. It was the first non all-terrain production car equipped with four-wheel drive and an anti-lock braking system. The powe ...
, and the experimental
all-wheel drive
An all-wheel drive vehicle (AWD vehicle) is one with a powertrain capable of providing power to all its wheels, whether full-time or on-demand.
The most common forms of all-wheel drive are:
;1x1 : All unicycles Reflecting one axle with one w ...
Ford Zodiac
The zodiac is a belt-shaped region of the sky that extends approximately 8° north or south (as measured in celestial latitude) of the ecliptic, the apparent path of the Sun across the celestial sphere over the course of the year. The pat ...
, but saw no further use; the system proved expensive and unreliable.
The first fully-electronic anti-lock braking system was developed in the late-1960s for the
Concorde
The Aérospatiale/BAC Concorde () is a retired Franco-British supersonic airliner jointly developed and manufactured by Sud Aviation (later Aérospatiale) and the British Aircraft Corporation (BAC).
Studies started in 1954, and France an ...
aircraft.
The modern ABS system was invented in 1971 by Mario Palazzetti (known as 'Mister ABS') in the Fiat Research Center and is now standard in almost every car. The system was called Antiskid and the patent was sold to Bosch who named it ABS.
[Google Patents]
US3707313A - Anti-skid braking systems - Google Patents
accessdate: 16. July 2020
Modern systems
Chrysler
Stellantis North America (officially FCA US and formerly Chrysler ()) is one of the " Big Three" automobile manufacturers in the United States, headquartered in Auburn Hills, Michigan. It is the American subsidiary of the multinational automoti ...
, together with the
Bendix Corporation
Bendix Corporation is an American manufacturing and engineering company which, during various times in its existence, made automotive brake shoes and systems, vacuum tubes, aircraft brakes, aeronautical hydraulics and electric power systems, av ...
, introduced a computerized, three-channel, four-sensor all-wheel ABS called "Sure Brake" for its 1971
Imperial
Imperial is that which relates to an empire, emperor, or imperialism.
Imperial or The Imperial may also refer to:
Places
United States
* Imperial, California
* Imperial, Missouri
* Imperial, Nebraska
* Imperial, Pennsylvania
* Imperial, Texa ...
. It was available for several years thereafter, functioned as intended, and proved reliable. In 1969, Ford introduced an anti-lock braking system called "Sure-Track" to the rear wheels of the
Lincoln Continental Mark III
The Continental Mark III is a personal luxury car marketed by Lincoln from 1969–1971 model years. The namesake successor of the 1956–1957 Continental Mark II, the Mark III again served as the flagship vehicle of Ford Motor Company. Offered ...
and
Ford Thunderbird
The Ford Thunderbird (colloquially called the T-Bird) is a personal luxury car produced by Ford from model years 1955 until 1997 and 2002 until 2005 across 11 distinct generations. Introduced as a two-seat convertible, the Thunderbird was pro ...
, as an option; it became standard in 1971. The Sure-Track braking system was designed with help from Kelsey-Hayes. In 1971,
General Motors
The General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. It is the largest automaker in the United States and ...
introduced the "Trackmaster" rear-wheel only ABS as an option on their
rear-wheel drive
Rear-wheel drive (RWD) is a form of engine and transmission layout used in motor vehicles, in which the engine drives the rear wheels only. Until the late 20th century, rear-wheel drive was the most common configuration for cars.
Most rear-wheel ...
Cadillac
The Cadillac Motor Car Division () is a division of the American automobile manufacturer General Motors (GM) that designs and builds luxury vehicles. Its major markets are the United States, Canada, and China. Cadillac models are distributed i ...
models and the
Oldsmobile Toronado
The Oldsmobile Toronado is a personal luxury car manufactured and marketed by the Oldsmobile division of General Motors from 1966 to 1992 over four generations. The Toronado was noted for its transaxle version of GM's Turbo-Hydramatic transmission ...
. In the same year,
Nissan
, trade name, trading as Nissan Motor Corporation and often shortened to Nissan, is a Japanese multinational corporation, multinational Automotive industry, automobile manufacturer headquartered in Nishi-ku, Yokohama, Japan. The company sells ...
offered an EAL (Electro Anti-lock System) developed by Japanese company
Denso as an option on the
Nissan President
The is a Japanese luxury sedan that manufactured and marketed by Nissan from 1965 to 2010 as a JDM luxury sedan, the flagship of Nissan's range, marketed at its '' Nissan Motor Store'' dealerships.
Initially marketed in the JDM, in the late ...
, which became
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
's first electronic ABS.
1971
Imperial became the first production car with a 4 wheel computer-operated anti-lock braking system. Toyota introduced electronically controlled anti-skid brakes on
Toyota Crown
The is an automobile which has been produced by Toyota in Japan since 1955. It is primarily a line of mid-size luxury cars that is marketed as an upmarket offering in the Toyota lineup.
Introduced in 1955 as the Toyopet Crown, it has served ...
. In 1972, four-wheel-drive
Triumph 2500
The Roman triumph (Latin triumphus) was a celebration for a victorious military commander in ancient Rome. For later imitations, in life or in art, see Trionfo. Numerous later uses of the term, up to the present, are derived directly or indirectl ...
Estates were fitted with
Mullard
Mullard Limited was a British manufacturer of electronic components. The Mullard Radio Valve Co. Ltd. of Southfields, London, was founded in 1920 by Captain Stanley R. Mullard, who had previously designed thermionic valves for the Admir ...
electronic systems as standard. Such cars were very rare however and very few survive today.
1971: First truck application: "Antislittamento" system developed by ''
Fiat
Fiat Automobiles S.p.A. (, , ; originally FIAT, it, Fabbrica Italiana Automobili di Torino, lit=Italian Automobiles Factory of Turin) is an Italian automobile manufacturer, formerly part of Fiat Chrysler Automobiles, and since 2021 a subsidiary ...
Veicoli Industriali'' and installed on
Fiat
Fiat Automobiles S.p.A. (, , ; originally FIAT, it, Fabbrica Italiana Automobili di Torino, lit=Italian Automobiles Factory of Turin) is an Italian automobile manufacturer, formerly part of Fiat Chrysler Automobiles, and since 2021 a subsidiary ...
truck model 691N1.
1976:
WABCO began the development of the anti-locking braking system on commercial vehicles to prevent locking on slippery roads, followed in 1986 by the electronic braking system (EBS) for heavy-duty vehicles.
1978:
Mercedes-Benz W116
The Mercedes-Benz W116 is a series of flagship luxury sedans produced from September 1972 until 1980. The W116 automobiles were the first Mercedes-Benz models to be officially called S-Class, although earlier sedan models had already unofficiall ...
As one of the firsts, used an electronic four-wheel multi-channel anti-lock braking system (ABS) from
Bosch as an option from 1978 on.
1982: Honda introduced electronically controlled multi-channel ALB (Anti Locking Brakes) as an option for the second generation of Prelude, launched worldwide in 1982. Additional info: the general agent for Honda in Norway required all Preludes for the Norwegian market to have the ALB-system as a standard feature, making Honda Prelude be the first car delivered in Europe with ABS as a standard feature. The Norwegian general agent also included a sunroof and other options to be standard equipment in Norway, adding more luxury to the Honda brand. However, the Norwegian tax system made the well-equipped car very expensive, and the sales suffered from high costs. From 1984 the ALB-system, as well as the other optional features from Honda, was no longer a standard feature in Norway.
In 1985 the
Ford Scorpio
The Ford Scorpio is an executive car that was produced by Ford Europe from 1985 to 1998. It was the replacement for the European Ford Granada line (although in the UK and Ireland the Scorpio was marketed under the Granada name until 1994). Li ...
was introduced to the European market with a Teves electronic system throughout the range as standard. For this the model was awarded the coveted
European Car of the Year
The European Car of the Year ("ECOTY") award is an international Car of the Year award established in 1964, by a collective of automobile magazines from different countries in Europe. The current organising companies of the award are ''Auto'' (Ita ...
Award in 1986, with very favorable praise from motoring journalists. After this success, Ford began research into Anti-Lock systems for the rest of their range, which encouraged other manufacturers to follow suit.
Since 1987 ABS has been standard equipment on all
Mercedes-Benz
Mercedes-Benz (), commonly referred to as Mercedes and sometimes as Benz, is a German luxury and commercial vehicle automotive brand established in 1926. Mercedes-Benz AG (a Mercedes-Benz Group subsidiary established in 2019) is headquartere ...
automobiles.
Lincoln
Lincoln most commonly refers to:
* Abraham Lincoln (1809–1865), the sixteenth president of the United States
* Lincoln, England, cathedral city and county town of Lincolnshire, England
* Lincoln, Nebraska, the capital of Nebraska, U.S.
* Lincol ...
followed suit in 1993.
In 1988,
BMW introduced the first
motorcycle
A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle steered by a handlebar. Motorcycle design varies greatly to suit a range of different purposes: long-distance travel, commuting, cruising ...
with an
electro-hydraulic ABS: the
BMW K100
The BMW K100 is a family of four-cylinder 987 cc motorcycles that were manufactured by BMW from 1983 to 1992.
Background
As the 1970s came to an end, BMW faced three problems from developing its flat-twin boxer engine further:
*Emissions r ...
.
Yamaha Yamaha may refer to:
* Yamaha Corporation, a Japanese company with a wide range of products and services, established in 1887. The company is the largest shareholder of Yamaha Motor Company (below).
** Yamaha Music Foundation, an organization estab ...
Introduced the FJ1200 model with optional ABS in 1991.
Honda
is a Japanese public multinational conglomerate manufacturer of automobiles, motorcycles, and power equipment, headquartered in Minato, Tokyo, Japan.
Honda has been the world's largest motorcycle manufacturer since 1959, reaching a product ...
followed suit in 1992 with the launch of its first motorcycle ABS on the
ST1100
The Honda ST series, also known as the ''Pan-European'' in Europe, is a duo of Sport Touring motorcycles comprising the ST1100 and the later ST1300.
Following the launch of the Gold Wing, which was very successful in the US, Honda's marketing tea ...
Pan European. In 2007,
Suzuki
is a Japan, Japanese multinational corporation headquartered in Minami-ku, Hamamatsu, Japan. Suzuki manufactures automobiles, motorcycles, All-terrain vehicle, all-terrain vehicles (ATVs), outboard motor, outboard marine engines, wheelchairs ...
launched its
GSF1200SA (Bandit) with an ABS. In 2005, Harley-Davidson began offering an ABS option on police bikes.
Operation
The anti-lock brake controller is also known as the CAB (Controller Anti-lock Brake).
Typically ABS includes a central
electronic control unit
An electronic control unit (ECU), also known as an electronic control module (ECM), is an embedded system in automotive electronics that controls one or more of the electrical systems or subsystems in a car or other motor vehicle.
Modern vehic ...
(ECU), four
wheel speed sensor
A wheel speed sensor (WSS) or vehicle speed sensor (VSS) is a type of tachometer. It is a sender device used for reading the speed of a vehicle's wheel rotation. It usually consists of a toothed ring and pickup.
Automotive wheel speed sensor ...
s, and at least two hydraulic valves within the brake
hydraulics
Hydraulics (from Greek: Υδραυλική) is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counter ...
. The ECU constantly monitors the
rotational speed
Rotational frequency (also known as rotational speed or rate of rotation) of an object Rotation around a fixed axis, rotating around an axis is the frequency of rotation of the object. Its unit is revolution per minute (rpm), cycle per second ...
of each wheel; if it detects the wheel rotating significantly slower than the speed of the vehicle, 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 systems can apply or release braking pressure 15 times per second.
[Nice, Karim]
How "Anti-Lock Brakes Work"
Retrieved October 2, 2010. Because of this, the wheels of cars equipped with ABS are practically impossible to lock even during panic braking in extreme conditions.
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.
Modern ABS applies individual brake pressure to all four wheels through a control system of hub-mounted sensors and a dedicated
micro-controller
A microcontroller (MCU for ''microcontroller unit'', often also MC, UC, or μC) is a small computer on a single VLSI integrated circuit (IC) chip. A microcontroller contains one or more CPUs (processor cores) along with memory and programmable ...
. ABS is offered or comes standard on most road vehicles produced today and is the foundation for electronic stability control systems, which are rapidly increasing in popularity due to the vast reduction in the price of vehicle electronics over the years.
Modern electronic stability control (ESC) systems are an evolution of the ABS concept. Here, a minimum of two additional sensors are added to help the system work: these are a
steering wheel
A steering wheel (also called a driving wheel (UK), a hand wheel, or simply wheel) is a type of steering control in vehicles.
Steering wheels are used in most modern land vehicles, including all mass-production automobiles, buses, light and ...
angle sensor and a
gyroscopic
A gyroscope (from Ancient Greek γῦρος ''gŷros'', "round" and σκοπέω ''skopéō'', "to look") is a device used for measuring or maintaining orientation and angular velocity. It is a spinning wheel or disc in which the axis of rotat ...
sensor. The theory of operation is simple: when the gyroscopic sensor detects that the direction taken by the car does not coincide with what the steering wheel sensor reports, the ESC software will brake the necessary individual wheel(s) (up to three with the most sophisticated systems), so that the vehicle goes the way the driver intends. The steering wheel sensor also helps in the operation of
Cornering Brake Control
Cornering brake control (CBC) is an automotive safety system introduced by carmakers BMW and Mercedes-Benz (ESP Dynamic Cornering Assist and Curve Dynamic Assist). It is a further development and expansion of the anti-lock braking system, design ...
(CBC), since this will tell the ABS that wheels on the inside of the curve should brake more than wheels on the outside, and by how much.
ABS equipment may also be used to implement a
traction control system
A traction control system (TCS), also known as ASR (from german: Antriebsschlupfregelung, lit=drive slippage regulation), is typically (but not necessarily) a secondary function of the electronic stability control (ESC) on production motor vehicle ...
(TCS) on the acceleration of the vehicle. If, when accelerating, the tire loses traction, the ABS controller can detect the situation and take suitable action so that traction is regained. More sophisticated versions of this can also control throttle levels and brakes simultaneously.
The speed sensors of ABS are sometimes used in indirect
tire pressure monitoring system
A tire-pressure monitoring system (TPMS) monitors the air pressure inside the pneumatic tires on vehicles.
A TPMS reports real-time tire-pressure information to the driver, using either a gauge, a pictogram display, or a simple low-pressure wa ...
(TPMS), which can detect under-inflation of the tire(s) by the difference in the rotational speed of wheels.
Components
There are four main components of ABS:
wheel speed sensor
A wheel speed sensor (WSS) or vehicle speed sensor (VSS) is a type of tachometer. It is a sender device used for reading the speed of a vehicle's wheel rotation. It usually consists of a toothed ring and pickup.
Automotive wheel speed sensor ...
s,
valves
A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fitting ...
, a
pump
A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by mechanical action, typically converted from electrical energy into hydraulic energy. Pumps can be classified into three major groups according to the method they u ...
, and a
controller
Controller may refer to:
Occupations
* Controller or financial controller, or in government accounting comptroller, a senior accounting position
* Controller, someone who performs agent handling in espionage
* Air traffic controller, a person ...
.
![ABS Sensor GM IMG 0557](https://upload.wikimedia.org/wikipedia/commons/0/02/ABS_Sensor_GM_IMG_0557.JPG)
; Speed sensors(Encoders): A speed sensor is used to determine the acceleration or deceleration of the wheel. These sensors use a magnet and a
Hall effect sensor
A Hall effect sensor (or simply Hall sensor) is a type of sensor which detects the presence and magnitude of a magnetic field using the Hall effect. The output voltage of a Hall sensor is directly proportional to the strength of the field. ...
, or a toothed wheel and an
electromagnetic coil
An electromagnetic coil is an electrical Electrical conductivity, conductor such as a wire in the shape of a wiktionary:coil, coil (spiral or helix). Electromagnetic coils are used in electrical engineering, in applications where electric curre ...
to generate a signal. The rotation of the wheel or differential induces a magnetic field around the sensor. The fluctuations of this magnetic field generate a voltage in the sensor. Since the voltage induced in the sensor is a result of the rotating wheel, this sensor can become inaccurate at slow speeds. The slower rotation of the wheel can cause inaccurate fluctuations in the magnetic field and thus cause inaccurate readings to the controller.
; Valves: There is a valve in the brake line of each brake controlled by the ABS. On some systems, the valve has three positions:
* In position one, the valve is open; pressure from the master cylinder is passed right through to the brake.
* In position two, the valve blocks the line, isolating that brake from the master cylinder. This prevents the pressure from rising further should the driver push the brake pedal harder.
* In position three, the valve releases some of the pressure from the brake.
![ABS HCU April 2018](https://upload.wikimedia.org/wikipedia/commons/f/f8/ABS_HCU_April_2018.jpg)
The majority of problems with the valve system occur due to clogged valves. When a valve is clogged it is unable to open, close, or change position. An inoperable valve will prevent the system from modulating the valves and controlling pressure supplied to the brakes.
![ABS module April, 2018](https://upload.wikimedia.org/wikipedia/commons/0/08/ABS_module_April%2C_2018.jpg)
; Pump: The pump in the ABS is used to restore the pressure to the hydraulic brakes after the valves have released it. A signal from the controller will release the valve at the detection of wheel slip. After a valve releases the pressure supplied from the user, the pump is used to restore the desired amount of pressure to the braking system. The controller will modulate the pump's status in order to provide the desired amount of pressure and reduce slipping.
; Controller: The controller is an
ECU type unit in the car which receives information from each individual wheel speed sensor. If a wheel loses traction, the signal is sent to the controller. The controller will then limit the brake force (EBD) and activate the ABS modulator which actuates the braking valves on and off.
Use
There are many different variations and control
algorithm
In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific Computational problem, problems or to perform a computation. Algorithms are used as specificat ...
s for use in ABS. One of the simpler systems works as follows:
# The controller monitors the speed sensors at all times. It is looking for decelerations in the wheel that are out of the ordinary. Right before a wheel locks up, it will experience a rapid deceleration. If left unchecked, the wheel would stop much more quickly than any car could. It might take a car two to four seconds to stop from 60 mph (96.6 km/h) under ideal conditions, but a wheel that locks up could stop spinning in less than a second.
# The ABS controller knows that such a rapid deceleration of the car is impossible (and in actuality the rapid deceleration means the wheel is about to slip), so it reduces the pressure to that brake until it sees an acceleration, then it increases the pressure until it sees the deceleration again. It can do this very quickly before the wheel can actually significantly change speed. The result is that the wheel slows down at the same rate as the car, with the brakes keeping the wheels very near the point at which they will start to lock up. This gives the system maximum braking power.
# This replaces the need to manually pump the brakes while driving on a slippery or a low traction surface, allowing to steer even in most emergency braking conditions.
# When the ABS is in operation the driver will feel a pulsing in the brake pedal; this comes from the rapid opening and closing of the valves. This pulsing also tells the driver that the ABS has been triggered.
Brake types
Anti-lock braking systems use different schemes depending on the type of brakes in use. They can be differentiated by the number of channels: that is, how many valves that are individually controlled—and the number of speed sensors.
; 1) Four-channel, four-sensor ABS: There is a speed sensor on all four wheels and a separate valve for all four wheels. With this setup, the controller monitors each wheel individually to make sure it is achieving maximum braking force.
; 2) Three-channel, four-sensor ABS: There is a speed sensor on all four wheels and a separate valve for each of the front wheels, but only one valve for both of the rear wheels. Older vehicles with four-wheel ABS usually use this type.
; 3) Three-channel, three-sensor ABS: This scheme, commonly found on pickup trucks with four-wheel ABS, has a speed sensor and a valve for each of the front wheels, with one valve and one sensor for both rear wheels. The speed sensor for the rear wheels is located in the rear axle. This system provides individual control of the front wheels, so they can both achieve maximum braking force. The rear wheels, however, are monitored together; they both have to start to lock up before the ABS will activate on the rear. With this system, it is possible that one of the rear wheels will lock during a stop, reducing brake effectiveness. This system is easy to identify, as there are no individual speed sensors for the rear wheels.
;4) Two-channel, four-sensor ABS: This system, commonly found on passenger cars from the late '80s through the mid-1990s, uses a speed sensor at each wheel, with one control valve each for the front and rear wheels as a pair. If the speed sensor detects lock up at any individual wheel, the control module pulses the valve for both wheels on that end of the car.
; 5) One-channel, one-sensor ABS: This system is commonly found on pickup trucks, SUVs, and vans with rear-wheel ABS. It has one valve, which controls both rear wheels, and a one-speed sensor, located in the rear axle. This system operates the same as the rear end of a three-channel system. The rear wheels are monitored together and they both have to start to lock up before the ABS kicks in. In this system it is also possible that one of the rear wheels will lock, reducing brake effectiveness. This system is also easy to identify, as there are no individual speed sensors for any of the wheels.
Effectiveness
A 2004 Australian study by Monash University Accident Research Centre found that ABS:
* Reduced the risk of
multiple vehicle crashes by 18 percent,
* Increased the risk of
run-off-road crashes by 35 percent.
On high-traction surfaces such as
bitumen
Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...
, or
concrete
Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...
, many (though not all) ABS-equipped cars are able to attain braking distances better (i.e. shorter) than those that would be possible without the benefit of ABS. In real-world conditions, even an alert and experienced driver without ABS would find it difficult to match or improve on the performance of a typical driver with a modern ABS-equipped vehicle. ABS reduces the chances of crashing, and/or the severity of impact. The recommended technique for non-expert drivers in an ABS-equipped car, in a typical full-braking emergency, is to press the brake pedal as firmly as possible and, where appropriate, to steer around obstructions. In such situations, ABS will significantly reduce the chances of a skid and subsequent loss of control.
In gravel, sand, and deep snow, ABS tends to increase braking distances. On these surfaces, locked wheels dig in and stop the vehicle more quickly. ABS prevents this from occurring. Some ABS calibrations reduce this problem by slowing the cycling time, thus letting the wheels repeatedly briefly lock and unlock. Some vehicle manufacturers provide an "off-road" button to turn the ABS function off. The primary benefit of ABS on such surfaces is to increase the ability of the driver to maintain control of the car rather than go into a skid, though the loss of control remains more likely on soft surfaces such as gravel or on slippery surfaces such as snow or ice. On a very slippery surface such as sheet ice or gravel, it is possible to lock multiple wheels at once, and this can defeat ABS (which relies on comparing all four wheels and detecting individual wheels skidding). The availability of ABS relieves most drivers from learning threshold braking.
A June 1999
National Highway Traffic Safety Administration
The National Highway Traffic Safety Administration (NHTSA ) is an agency of the U.S. federal government, part of the Department of Transportation. It describes its mission as "Save lives, prevent injuries, reduce vehicle-related crashes" rela ...
(NHTSA) study found that ABS increased stopping distances on loose gravel by an average of 27.2 percent.
According to the NHTSA,
"ABS works with your regular braking system by automatically pumping them. In vehicles not equipped with ABS, the driver has to manually pump the brakes to prevent wheel lockup. In vehicles equipped with ABS, your foot should remain firmly planted on the brake pedal, while ABS pumps the brakes for you so you can concentrate on steering to safety."
When activated, some earlier ABSes caused the brake pedal to pulse noticeably. As most drivers rarely or do not brake hard enough to cause brake lock-up, and drivers typically do not read the vehicle's owner's manual, this may not be noticeable until an emergency. Some manufacturers have therefore implemented a
brake assist
Brake assist (BA or BAS) or emergency brake assist (EBA) is a term for an automobile braking technology that increases braking pressure in an emergency. The first application was developed jointly by Daimler-Benz and TRW/LucasVarity. Research c ...
system that determines that the driver is attempting a "panic stop" (by detecting that the brake pedal was depressed very quickly, unlike a normal stop where the pedal pressure would usually be gradually increased. Some systems additionally monitor the rate at the accelerator was released, and/or the time between accelerator release and brake application) and the system automatically increases braking force where not enough pressure is applied. Hard or panic braking on bumpy surfaces, because of the bumps causing the speed of the wheel(s) to become erratic may also trigger the ABS, sometimes causing the system to enter its ice mode, where the system severely limits maximum available braking power. Nevertheless, ABS significantly improves safety and control for drivers in most on-road situations.
Anti-lock brakes are the subject of some experiments centred around
risk compensation
Risk compensation is a theory which suggests that people typically adjust their behavior in response to perceived levels of risk, becoming more careful where they sense greater risk and less careful if they feel more protected. Although usually ...
theory, which asserts that drivers adapt to the safety benefit of ABS by driving more aggressively. In a
Munich
Munich ( ; german: München ; bar, Minga ) is the capital and most populous city of the States of Germany, German state of Bavaria. With a population of 1,558,395 inhabitants as of 31 July 2020, it is the List of cities in Germany by popu ...
study, half a fleet of
taxicab
A taxi, also known as a taxicab or simply a cab, is a type of vehicle for hire with a driver, used by a single passenger or small group of passengers, often for a non-shared ride. A taxicab conveys passengers between locations of their choice ...
s was equipped with anti-lock brakes, while the other half had conventional brake systems. The crash rate was substantially the same for both types of cab, and Wilde concludes this was due to drivers of ABS-equipped cabs taking more risks, assuming that ABS would take care of them, while the non-ABS drivers drove more carefully since ABS would not be there to help in case of a dangerous situation.
The
Insurance Institute for Highway Safety
The Insurance Institute for Highway Safety (IIHS) is a U.S. nonprofit organization funded by auto insurance companies, established in 1959 and headquartered in Arlington, Virginia. It works to reduce the number of motor vehicle traffic collision ...
released a study in 2010 that found motorcycles with ABS 37% less likely to be involved in a fatal crash than models without ABS.
ABS on motorcycles
![ABS Vorderrad BMW K75](https://upload.wikimedia.org/wikipedia/commons/7/7c/ABS_Vorderrad_BMW_K75.jpg)
On a motorcycle, an anti-lock brake system prevents the wheels of a
powered two wheeler from locking during
braking
A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction.
Background ...
situations. Based on information from
wheel speed sensor
A wheel speed sensor (WSS) or vehicle speed sensor (VSS) is a type of tachometer. It is a sender device used for reading the speed of a vehicle's wheel rotation. It usually consists of a toothed ring and pickup.
Automotive wheel speed sensor ...
s the ABS unit adjusts the pressure of the brake fluid in order to keep
traction during deceleration to avoid accidents. Motorcycle ABS helps the rider to maintain stability during braking and to decrease the stopping distance. It provides traction even on low
friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction:
*Dry friction is a force that opposes the relative lateral motion of t ...
surfaces. While older ABS models are derived from cars, recent ABS is the result of research, oriented on the specifics of motorcycles in case of size, weight, and functionality. National and international organizations evaluate Motorcycle ABS as an important factor to increase safety and reduce motorcycle accident numbers. The
European Commission
The European Commission (EC) is the executive of the European Union (EU). It operates as a cabinet government, with 27 members of the Commission (informally known as "Commissioners") headed by a President. It includes an administrative body o ...
passed legislation in 2012 that made the fitment with ABS for all new motorcycles above 125 cm
3 to be mandatory from 1 January 2016. ''Consumer Reports'' said in 2016 that "ABS is commonly offered on large, expensive models, but it has been spreading to several entry-level sportbikes and midsized bikes".
History of motorcycle ABS
In 1988, BMW introduced an electronic/
hydraulic
Hydraulics (from Greek: Υδραυλική) is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counter ...
ABS for motorcycles, ten years after Daimler Benz and Bosch released the first four-wheel vehicle ABS for series production. Motorcycles of
BMW K100
The BMW K100 is a family of four-cylinder 987 cc motorcycles that were manufactured by BMW from 1983 to 1992.
Background
As the 1970s came to an end, BMW faced three problems from developing its flat-twin boxer engine further:
*Emissions r ...
series were optionally equipped with the ABS, which added 11 kg to the bike. It was developed together with
FAG Kugelfischer and regulated the pressure in the braking circuits via a plunger
piston
A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tig ...
. Japanese manufacturers followed with an ABS option by 1992 on the
Honda ST1100 and the
Yamaha FJ1200
The Yamaha FJ1100 and FJ1200 are sport touring motorcycles that were produced by Yamaha between 1984 and 1996.
FJ1100
Yamaha released the FJ1100 for model years 1984 and 1985. The FJ1100 was designed by GK Dynamics. This class is characterised b ...
.
Continental presented its first Motorcycle Integral ABS (MIB) in 2006. It has been developed in cooperation with BMW and weighed 2.3 kg.
While the first generation of motorcycle ABS weighed around 11 kg. The current generation (2011) presented by Bosch in 2009 weighs 0.7 kg (ABS base) and 1.6 kg (ABS enhanced) with integral braking.
Basic principle
Wheel speed
sensor
A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon.
In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends ...
s mounted on the front and rear wheel constantly measures the rotational speed of each wheel and delivers this information to an
Electronic Control Unit
An electronic control unit (ECU), also known as an electronic control module (ECM), is an embedded system in automotive electronics that controls one or more of the electrical systems or subsystems in a car or other motor vehicle.
Modern vehic ...
(ECU). The ECU detects two things: 1) if the deceleration of one wheel exceeds a fixed threshold and 2) whether the brake slip, calculated based on information of both wheels, rises above a certain percentage and enters an unstable zone. These are indicators for a high possibility of a locking wheel. To countermeasure these irregularities the ECU signals the hydraulic unit to hold or to release pressure. After signals show the return to the stable zone, the pressure is increased again. Past models used a piston for the control of the
fluid pressure
Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...
. Most recent models regulate the pressure by rapidly opening and closing
solenoid valve
A solenoid valve is an electromechanically operated valve.
Solenoid valves differ in the characteristics of the electric current they use, the strength of the magnetic field they generate, the mechanism they use to regulate the fluid, and the ty ...
s.
While the basic principle and
architecture
Architecture is the art and technique of designing and building, as distinguished from the skills associated with construction. It is both the process and the product of sketching, conceiving, planning, designing, and constructing building ...
has been carried over from passenger car ABS, typical motorcycle characteristics have to be considered during the development and application processes.
One characteristic is the change of the dynamic wheel load during braking. Compared to cars, the wheel load changes are more drastic, which can lead to a wheel lift up and a fall over. This can be intensified by a soft suspension. Some systems are equipped with a rear-wheel lift-off mitigation functionality. When the indicators of a possible rear lift-off are detected, the system releases brake pressure on the front wheel to counter this behavior.
Another difference is that in the case of the motorcycle the front wheel is much more important for stability than the rear wheel. If the front wheel locks up between 0.2-0.7s, it loses gyrostatic forces and the motorcycle starts to oscillate because of the increased influence of side forces operating on the wheel contact line. The motorcycle becomes unstable and falls.
Anti-lock Braking System (ABS)
''Piston Systems'': The pressure release in this system is realized through the movement of a spring-tensioned piston. When pressure should be released, a linear motor pulls back the plunger piston and opens up more space for the fluid. The system was used for example in the ABS I (1988) and ABS II (1993) of BMW. The ABS II differed in size and an electronically controlled
friction clutch was mounted on the shaft instead of a plunger. Further displacement sensors record the travel distance of the piston to allow the control unit a more precise regulation. Honda also uses this system of pressure modulation for big sports and
touring bikes.
''Valve and Pump Systems'': The main parts which are part of the pressure modulation system are solenoid inlet and outlet valves, a pump, motor, and accumulators/reservoirs. The number of the valves differs from model to model due to additional functionalities and the number of brake channels. Based on the input of the ECU, coils operate the inlet and outlet valves. During pressure release, the brake fluid is stored in accumulators. In this open system approach, the fluid is then brought back in the brake circuit via a pump operated by a motor that is felt through pulsation on the brake lever.
Regenerative Anti-Lock Braking for Electric 2-wheel vehicles (eABS)
Electric vehicles can recapture the energy from rear wheel braking.
Combined Braking System (CBS)
Different from cars or trains, motorcycle rear and front wheels are controlled separately. If the rider only brakes with one wheel, this braked wheel tends to lock up faster than if both brakes had been applied. A
Combined Braking System
A combined braking system (CBS), also called linked braking system (LBS), is a system for linking front and rear brakes on a motorcycle or scooter. In this system, the rider's action of depressing one of the brake levers applies both front and re ...
therefore distributes the brake force also to the non-braked wheel to lower the possibility of a lock-up, increase deceleration and reduce
suspension
Suspension or suspended may refer to:
Science and engineering
* Suspension (topology), in mathematics
* Suspension (dynamical systems), in mathematics
* Suspension of a ring, in mathematics
* Suspension (chemistry), small solid particles suspend ...
pitch.
With a single
ear
An ear is the organ that enables hearing and, in mammals, body balance using the vestibular system. In mammals, the ear is usually described as having three parts—the outer ear, the middle ear and the inner ear. The outer ear consists of ...
CBS the brake pressure applied on the rear brake (pedal) is simultaneously distributed to the front wheel. A delay valve cuts the hydraulic pressure to assure that only when strong braking is applied, the pressure is also created at the front wheel. Honda's first street motorcycle with a combined braking system (then called Unified Braking) was the 1983
GL1100. This system was derived from the 1970s
RCB1000 world endurance race bike.
Larger models with two front
discs use a dual CBS System. The system was first installed by Moto Guzzi in 1975. Here, applied brake pressure at the front is also applied to the rear wheel and vice versa. If the front lever is applied, the pressure is built up at 4 of the 6 pots in the 2 calipers at the front. A secondary master cylinder at the front wheel distributes remaining pressure to the rear wheel through a proportional control valve and acts on 2 of the 3 calipers. If a strong brake force is applied at the rear wheel force is also distributed to 2 of the 6 pots of the front wheel. More modern dual CBS use front and rear calipers (and all pots) according to a preset load ratio of front to rear. The proportioning was originally controlled by complex all-hydraulic systems interlinking the front and rear, with a fixed delay or by sensing weight distribution changes. As early as 2001 an electrohydraulic system was introduced by BMW.
CBS and ABS
CBS helps to reduce the danger of wheel locks and fall downs but in certain situations, it is possible that CBS causes a fall down. If brake pressure is distributed from the rear wheel to the front wheel and the friction of the surfaces changes suddenly (puddle, ice on the street) the front wheel might lock even if only the rear brake has been applied. This would lead to a loss of stability and a fall down. CBS is therefore combined with ABS to avoid this on a motorcycle.
Different approaches are possible to realize this combination:
''Without active pressure Build up''
Single Version: A third additional channel links the rear wheel circuit through a delay valve to the front brake. Strong brake pressure at the rear wheel (or both wheels) pressurizes both brake circuits however this pressure is adjusted according to wheel speed and brake slip.
The dual version combines Hondas Dual CBS with a secondary master cylinder and a proportional control valve
ith Piston ABSA modulator regulates the pressure for each
''With Active Pressure Build up''
In 2009, Honda introduced the electronic controlled combined ABS for its high-performance sports bikes which utilize brake by wire technology. The brake input of the rider is measured by pressure sensors and the information is provided to an ECU. Together with the information of the wheel speed sensors, the ECU calculates the optimal distribution of pressure to prevent lockups and to provide the best possible deceleration. Based on this output a motor for each wheel operates a pump that builds up and regulates the brake pressure on the wheel. This system offers a fast reaction time because of the brake by wire functionality.
The MIB (Motorcycle integral Braking system) from Continental Teves and the eCBS (electronic CBS) in the enhanced Motorcycle ABS from Bosch are results of another approach. These systems are based on the pump and valve approach. Through additional valves, stronger pumps and a more powerful motor the system can actively build up pressure. The input pressure of the rider is measured with pressure sensors at the lever and pedal. The pump then builds up additional pressure adjusted to riding conditions. A partial integral System is designed for working in one direction only: front→rear or rear→front. A fully-integrated system works in both directions.
Because these systems are electronically controlled and are able to build up pressure actively, they offer the opportunity to adjust the motorcycle braking behavior to the rider. CBS and ABS can be switched off by experienced riders and also different regulation modes with higher and lower thresholds can be chosen, such as the rain or slick mode in the BMW S1000RR.
Cornering ABS
ABS that works while turning. Designated by various names.
Safety and legislation
Safety
The
Insurance Institute for Highway Safety
The Insurance Institute for Highway Safety (IIHS) is a U.S. nonprofit organization funded by auto insurance companies, established in 1959 and headquartered in Arlington, Virginia. It works to reduce the number of motor vehicle traffic collision ...
(IIHS) conducted a study on the effectiveness of ABS for motorcycles and came to the conclusion that motorcycles above 250 cm
3 without ABS are 37 percent more likely to be involved in fatal crashes and a study of the Swedish Road Administration came to the conclusion that 48 percent of all severe and fatal motorcycle accidents above 125 cm
3 could be avoided due to motorcycle ABS.
These studies caused the EU commission to initiate a legislative process in 2010 that was passed in 2012 and led to ABS for motorcycles above 125 cm
3 becoming mandatory from 2016 onwards. Organizations like the Fédération Internationale de l'Automobile and the Institute of advanced Motorists (IAM) demanded the implementation of this legislation already for 2015.
On the other hand, some motorcycle riders are protesting against a compulsory ABS for all bikes because they call for a possibility to switch the system off, for off-road usage or for other reasons.
In 2011 the
United Nations
The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and international security, security, develop friendly relations among nations, achieve international cooperation, and be ...
(UN) started the
Decade of Action for Road Safety. The main goal is to save 5 million lives until 2020 through global cooperation.
One part of their global plan is to: Encourage universal deployment of crash avoidance technologies with proven effectiveness such as
Electronic Stability Control
Electronic stability control (ESC), also referred to as electronic stability program (ESP) or dynamic stability control (DSC), is a computerized technology that improves a vehicle's stability by detecting and reducing loss of traction ( skiddi ...
and Anti-Lock Braking Systems in motorcycles.
Laws and regulations
ABS is required on all new passenger cars sold in the EU since 2004. In the United States, the NHTSA has mandated ABS in conjunction with Electronic Stability Control under the provisions of FMVSS 126 as of September 1, 2012.
UN Regulation No. 78, related to the braking of vehicles of categories L1, L2, L3, L4 and L5 (motorbikes) is applied by the European Union, Russia, Japan, Turkey, Ukraine, Australia and the United Kingdom.
Global technical regulation number 3 related to Motorcycle brake systems is applied by Canada, the European Union, Japan, Russia, and the United States.
Since 2016, the EU has required ABS on all new scooters, motorcycles, tricycles, and quads from 125 cc, otherwise CBS (or ABS).
Since 1 April 2019, India has required at least single-channel ABS on all new two-wheelers from 125 cc, otherwise CBS (or ABS). ABS has also been mandatory on all new cars and mini-buses from the same date.
Since 1 January 2019, Brazil has required ABS on all new motorcycles from 300 cc. ABS has been mandatory on all new cars since January 2014.
From 1 January 2024, Argentina will require ABS on all new motorcycles from 250 cc, CBS (or front wheel ABS) for on-road between 50 and 250cc. Or their electric equivalents. ABS has been mandatory on all new normal cars since January 2014.
From February 2025, Chile will require ABS on all new motorcycles from 150 cc or 11 kW, otherwise CBS (or ABS) from 50 cc or 4 kW from February 2026. ABS has been mandatory on all new cars since October 2020.
From October 2025, Colombia will require ABS on all new motorcycles from 150 cc or 11 kW, otherwise CBS (or ABS) from 50 cc or 4 kW.
From March 2027, Colombia will require ABS on all new motorcycles from 125 cc, below that with CBS (or ABS).
See also
*
*
Left-foot braking
Left-foot braking is the technique of using the left foot to operate the brake pedal in an automobile, leaving the right foot dedicated to the throttle pedal. It contrasts with the practice of using the left foot to operate the clutch pedal, leavi ...
*
Emergency brake assist
Brake assist (BA or BAS) or emergency brake assist (EBA) is a term for an automobile braking technology that increases braking pressure in an emergency. The first application was developed jointly by Daimler-Benz and TRW/ LucasVarity. Research ...
, or Brake assist system (BAS)
*Electronic stability control (ESP)
Further reading
*
*
References
External links
*
{{Authority control
Vehicle safety technologies
Mechanical power control
Motorcycle technology
Vehicle braking technologies