Misplaced Pages

#81918

59-534: ABS is an automated system that uses the principles of threshold braking and cadence braking , 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 , while still improving steering control. Since ABS

118-420: A Munich study, half a fleet of taxicabs 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

177-542: 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

236-427: 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, 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

295-536: A pump , and a controller . 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. There are many different variations and control algorithms for use in ABS. One of the simpler systems works as follows: Anti-lock braking systems use different schemes depending on

354-409: A dangerous situation. The Insurance Institute for Highway Safety released a study in 2010 that found motorcycles with ABS 37% less likely to be involved in a fatal crash than models without ABS. On a motorcycle, an anti-lock brake system prevents the wheels of a motorcycle from locking during braking situations. Based on information from wheel speed sensors the ABS unit adjusts the pressure of

413-421: A dedicated micro-controller . ABS is offered or comes standard on most road vehicles and is the foundation for electronic stability control systems, which are rapidly increasing in popularity due to the great 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

472-441: 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

531-472: 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 (NHTSA) study found that ABS increased stopping distances on loose gravel by an average of 27.2 percent. According to

590-408: 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 pedal (or lever) pressure to maximize the braking force developed by the tires . The optimal amount of braking force is developed at the point when the wheel just begins to slip . Braking beyond

649-475: Is also known as the CAB (Controller Anti-lock Brake). Typically 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 the wheel rotating significantly slower than the speed of the vehicle, a condition indicative of impending wheel lock, it actuates

SECTION 10

#1732786723082

708-515: Is difficult to consistently achieve during normal driving. This automobile -related article is a stub . You can help Misplaced Pages by expanding it . 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 . In 1953,

767-420: 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

826-409: 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. Piston Systems : The pressure release in this system

885-451: 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

944-549: The 736 cc Royal Enfield Interceptor in 1962. In 1958, a Royal Enfield Super Meteor was used by the Transport Research Laboratory to test the Maxaret anti-lock brake on motorcycles. The Maxaret works by detecting rapid decelerations of the wheel that may cause it to lock and releases and re-applies hydraulic pressure to the brake several times a second, keeping the average braking effort at

1003-469: 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 (TPMS), which can detect under-inflation of the tire(s) by the difference in the rotational speed of wheels. There are four main components of ABS: wheel speed sensors , valves ,

1062-419: 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 theory, which asserts that drivers adapt to the safety benefit of ABS by driving more aggressively. In

1121-577: The Dutch Fokker F27 Friendship (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,

1180-742: 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 was introduced to the European market with a Teves electronic system throughout the range as standard. For this the model

1239-458: 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

SECTION 20

#1732786723082

1298-453: The US export market led Royal Enfield to develop a 692 cc, overhead valve twin capable of 100 mph (160 km/h), which was launched as the Meteor. The engine was basically a modified 500 twin crankcase with 350 single (Bullet) pistons, valves and identical 90mm stroke length. In 1954, the Super Meteor was updated and fitted with a new cast alloy headlight nacelle (casquette) housing

1357-403: 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

1416-557: 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 surfaces. While older ABS models are derived from cars, recent Motorcycle ABS is the result of research, oriented to the specifics of motorcycles in case of size, weight, and functionality. National and international organizations have evaluated Motorcycle ABS to be an important factor in increasing safety and reducing

1475-432: 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

1534-423: 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 system that determines that the driver is attempting a "panic stop" (by detecting that the brake pedal was depressed very quickly, unlike

1593-439: 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

1652-434: 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

1711-448: 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

1770-466: 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 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

1829-404: The driver intends. The steering wheel sensor also helps in the operation of Cornering Brake Control (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 (TCS) on the acceleration of the vehicle. If, when accelerating, the tire loses traction,

Anti-lock braking system - Misplaced Pages Continue

1888-413: The driver via brake pedal pulsation. Some anti-lock systems can apply or release braking pressure 15 times per second. 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

1947-586: The first motorcycle with an electro-hydraulic ABS: the BMW K100 . Yamaha Introduced the FJ1200 model with optional ABS in 1991. 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 an ABS option on police bikes. The anti-lock brake controller

2006-666: The first four-wheel vehicle ABS for series production. Motorcycles of BMW K100 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 . Japanese manufacturers followed with an ABS option by 1992 on the Honda ST1100 and the Yamaha FJ1200 . Continental presented its first Motorcycle Integral ABS (MIB) in 2006. It has been developed in cooperation with BMW and weighed 2.3 kg. While

2065-416: The first generation of motorcycle ABS weighed around 11 kg, the generation (2011) presented by Bosch in 2009 weighs 0.7 kg (ABS base) and 1.6 kg (ABS enhanced) with integral braking. Wheel speed sensors mounted on the front and rear wheel constantly measures the rotational speed of each wheel and delivers this information to an Electronic Control Unit (ECU). The ECU detects two things: 1) if

2124-605: 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 racing car, the Jensen FF , and the experimental all-wheel drive Ford Zodiac , but saw no further use; the system proved expensive and unreliable. The first fully-electronic anti-lock braking system

2183-404: 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

2242-440: The maximum that can be used by the road surface and tyre combination. The experiments demonstrated that anti-lock brakes could be of great value on motorcycles, where skidding is involved in a high proportion of accidents. Stopping distances were reduced in almost all the tests, compared with locked wheel braking, but particularly on slippery surfaces, where the improvement could be as much as 30%. Royal Enfield's Technical Director at

2301-481: 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 and aircraft pioneer Gabriel Voisin 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

2360-510: The number and severity of motorcycle crashes and collisions. The European Commission passed legislation in 2012 that made the fitment with ABS for all new motorcycles above 125cc 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". In 1988, BMW introduced an electronic/ hydraulic ABS for motorcycles, ten years after Daimler Benz and Bosch released

2419-473: 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. Electric vehicles can recapture the energy from rear wheel braking. Threshold braking Threshold braking or limit braking

Anti-lock braking system - Misplaced Pages Continue

2478-1079: The option the True-Track Braking System on the Oldsmobile Toronado . In 1972, the option was made available in all Cadillacs. In 1971, Nissan offered an EAL (Electro Anti-lock System) developed by Japanese company Denso as an option on the Nissan President , which became Japan 's first electronic ABS. 1971: The 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 labeled as ESC (Electronic Skid Control). 1971: First truck application: "Antislittamento" system developed by Fiat Veicoli Industriali and installed on Fiat truck model 691N1. 1972: four-wheel-drive Triumph 2500 Estates were fitted with Mullard electronic systems as standard. Such cars were rare however and very few remain. 1976: WABCO began

2537-480: 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

2596-427: The slipping point causes the tire to slide and the frictional adhesion between the tire and driving surface is reduced. The aim of threshold braking is to keep the amount of tire slip at the optimal amount, the value that produces the maximum frictional, and thus braking force. When wheels are slipping significantly ( kinetic friction ), the amount of friction available for braking is typically substantially less than when

2655-495: The speedometer, ammeter and light switch. During 1955, the dynamo and coil ignition was replaced with a Lucas magdyno. This model was replaced by the Super Meteor in 1956 that sported a brand new frame. Based on the Royal Enfield Meteor Minor 496 cc overhead valve engine, the new model had a strengthened crank and improved clutch. The frame was also strengthened to handle the increased torque. The gearbox

2714-424: The stable zone, the pressure is increased again. Past models used a piston for the control of the fluid pressure . Most recent models regulate the pressure by rapidly opening and closing solenoid valves . While the basic principle and architecture has been carried over from passenger car ABS, typical motorcycle characteristics have to be considered during the development and application processes. One characteristic

2773-449: The system work: these are a steering wheel angle sensor and a gyroscopic 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

2832-438: 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

2891-462: 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. A 2004 Australian study by Monash University Accident Research Centre found that ABS: On high-traction surfaces such as bitumen , or concrete , many (though not all) ABS-equipped cars are able to attain braking distances better (i.e. shorter) than those that would be possible without

2950-407: 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

3009-411: The wheels are not slipping ( static friction ), thereby reducing the braking force and eliminating steering ability. Peak friction occurs between the static and dynamic endpoints, and this is the point that threshold braking tries to maintain. Because available friction at a given moment depends on many factors including road surface material, temperature, tire rubber compound and wear, threshold braking

SECTION 50

#1732786723082

3068-583: 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 and Ford Thunderbird , as an option; it became standard in 1971. The Sure-Track braking system was designed with help from Kelsey-Hayes. In 1971, General Motors introduced the "Trackmaster" rear-wheel only ABS as an option on their rear-wheel drive Cadillac models and called

3127-465: Was awarded the coveted European Car of the Year 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 automobiles. Lincoln followed suit in 1993. In 1988, BMW introduced

3186-669: Was developed in the late-1960s for the Concorde aircraft. The modern ABS system was invented in 1971 by Mario Palazzetti (known as 'Mister ABS') in the Fiat Research Center and has become standard in almost every car. The system was called Antiskid and the patent was sold to Bosch who named it ABS. Chrysler , together with the Bendix Corporation , introduced a computerized, three-channel, four-sensor all-wheel ABS called "Sure Brake" for its 1971 Imperial . It

3245-485: 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 . This latter function, depending on its specific capabilities and implementation, is known variously as electronic brakeforce distribution , traction control system , emergency brake assist , or electronic stability control (ESC). The concept for ABS predates

3304-482: Was modified so that the gear shift lever was concentric with the kick-starter. The compression ratio was increased to 7.25:1; it was upgraded with Lucas alternator and Amal Monobloc carburettor. Modified engines, incorporating electric start, were also produced and supplied by the factory for the Berkeley B95 and B105 car models during 1959 and 1960. The Super Meteor and the sporty Constellation were replaced by

3363-751: Was no public information of the test results. By the early 1950s, the Dunlop Maxaret anti-skid system was in widespread aviation use in the UK, with aircraft such as the Avro Vulcan and Handley Page Victor , Vickers Viscount , Vickers Valiant , English Electric Lightning , de Havilland Comet 2c , de Havilland Sea Vixen , and later aircraft, such as the Vickers VC10 , Hawker Siddeley Trident , Hawker Siddeley 125 , Hawker Siddeley HS 748 and derived British Aerospace ATP , and BAC One-Eleven , and

3422-515: 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 patented in 1928. Wässel, however, never developed a working product and neither did Robert Bosch who produced a similar patent eight years later. A similar braking system called Decelostat that used direct-current generators to measure wheel slippage

3481-678: Was used in railroads in the 1930s. By 1951, flywheel-based Decelostat was used in aircraft to provide anti skid in landings. The device was on trials first in the United States and later by the British. In 1954, Popular Science revealed that there was preliminary testing of the Decelostat system to prevent car swirling on a heavy brake by the US car manufacturers in Detroit . However, there

#81918