Brake
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, axle, or to prevent its motion, most accomplished by means of friction. Most brakes use friction between two surfaces pressed together to convert the kinetic energy of the moving object into heat, though other methods of energy conversion may be employed. For example, regenerative braking converts much of the energy to electrical energy, which may be stored for use. Other methods convert kinetic energy into potential energy in such stored forms as pressurized air or pressurized oil. Eddy current brakes use magnetic fields to convert kinetic energy into electric current in the brake disc, fin, or rail, converted into heat. Still other braking methods transform kinetic energy into different forms, for example by transferring the energy to a rotating flywheel. Brakes are applied to rotating axles or wheels, but may take other forms such as the surface of a moving fluid.
Some vehicles use a combination of braking mechanisms, such as drag racing cars with both wheel brakes and a parachute, or airplanes with both wheel brakes and drag flaps raised into the air during landing. Since kinetic energy increases quadratically with velocity, an object moving at 10 m/s has 100 times as much energy as one of the same mass moving at 1 m/s, the theoretical braking distance, when braking at the traction limit, is 100 times as long. In practice, fast vehicles have significant air drag, energy lost to air drag rises with speed. All wheeled vehicles have a brake of some sort. Baggage carts and shopping carts may have them for use on a moving ramp. Most fixed-wing aircraft are fitted with wheel brakes on the undercarriage; some aircraft feature air brakes designed to reduce their speed in flight. Notable examples include gliders and some World War II-era aircraft some fighter aircraft and many dive bombers of the era; these allow the aircraft to maintain a safe speed in a steep descent.
The Saab B 17 dive bomber and Vought F4U Corsair fighter used the deployed undercarriage as an air brake. Friction brakes on automobiles store braking heat in the drum brake or disc brake while braking conduct it to the air gradually; when traveling downhill some vehicles can use their engines to brake. When the brake pedal of a modern vehicle with hydraulic brakes is pushed against the master cylinder a piston pushes the brake pad against the brake disc which slows the wheel down. On the brake drum it is similar as the cylinder pushes the brake shoes against the drum which slows the wheel down.. Brakes electromagnetics. One brake may use several principles: for example, a pump may pass fluid through an orifice to create friction: Frictional brakes are most common and can be divided broadly into "shoe" or "pad" brakes, using an explicit wear surface, hydrodynamic brakes, such as parachutes, which use friction in a working fluid and do not explicitly wear; the term "friction brake" is used to mean pad/shoe brakes and excludes hydrodynamic brakes though hydrodynamic brakes use friction.
Friction brakes are rotating devices with a stationary pad and a rotating wear surface. Common configurations include shoes that contract to rub on the outside of a rotating drum, such as a band brake. Other brake configurations are less often. For example, PCC trolley brakes include a flat shoe, clamped to the rail with an electromagnet. A drum brake is a vehicle brake in which the friction is caused by a set of brake shoes that press against the inner surface of a rotating drum; the drum is connected to the rotating roadwheel hub. Drum brakes can be found on older car and truck models. However, because of their low production cost, drum brake setups are installed on the rear of some low-cost newer vehicles. Compared to modern disc brakes, drum brakes wear out faster due to their tendency to overheat; the disc brake is a device for stopping the rotation of a road wheel. A brake disc made of cast iron or ceramic, is connected to the wheel or the axle. To stop the wheel, friction material in the form of brake pads is forced mechanically, pneumatically or electromagnetically against both sides of the disc.
Friction attached wheel to slow or stop. Pumping brakes are used where a pump is part of the machinery. For example, an internal-combustion piston motor can have the fuel supply stopped, internal pumping losses of the engine create some braking; some engines use a valve override called a Jake brake to increase pumping losses. Pumping brakes can dump energy as heat, or can be regenerative brakes that recharge a pressure reservoir called a hydraulic accumulator. Electromagnetic brakes are often used where an electric motor is part of the machinery. For example, many hybrid gasoline/electric vehicles use the electric motor as a generator to charge electric batteries and as a regenerative brak
V8 engine
A V8 engine is an eight-cylinder V configuration engine with the cylinders mounted on the crankcase in two sets of four, with all eight pistons driving a common crankshaft. Most banks are set at a right angle to each other, some at a narrower angle, with 45°, 60°, 72° most common. In its simplest form, the V8 is two parallel inline-four engines sharing a common crankshaft. However, this simple configuration, with a flat- or single-plane crankshaft, has the same secondary dynamic imbalance problems as two straight-4s, resulting in vibrations in large engine displacements. Since the 1920s, most V8s have used the somewhat more complex crossplane crankshaft with heavy counterweights to eliminate the vibrations; this results in an engine, smoother than a V6, while being less expensive than a V12. Many racing V8s continue to use the single plane crankshaft because it allows faster acceleration and more efficient exhaust system designs. In 1902, Léon Levavasseur took out a patent on a light but quite powerful gasoline injected V8 engine.
He called it the'Antoinette' after the young daughter of his financial backer. From 1904 he installed this engine in a number of early aircraft; the aviation pioneer Alberto Santos-Dumont saw one of these boats in Côte d'Azur and decided to try it on his pusher configuration, canard-design 14-bis aircraft. Its early 24 hp at 1400 rpm version with only 55 kg of weight was interesting, but proved to be underpowered. Santos-Dumont ordered a more powerful version from Levavasseur, he changed its dimensions from the original 80 mm stroke and 80 mm bore to 105 mm stroke and 110 mm bore, obtaining 50 hp with 86 kg of weight, including cooling water. Its power-to-weight ratio was not surpassed for 25 years. Levavasseur produced its own line of V8 equipped aircraft, named Antoinette I to VIII. Hubert Latham piloted the V8 powered Antoinette IV and Antoinette VII in July 1909 on two failed attempts to cross the English Channel. However, in 1910, Latham used the VII with the same engine to become the first in the world to reach an altitude of 3600 feet.
Voisin constructed pusher biplanes with Antoinette engines notably the one first flown by Henry Farman in 1908. The V8 engine configuration was used in France by 1904, in race car and aircraft engines introduced by Renault, Buchet among others; some of these engines found their way into automobiles in small quantities. In 1905, Darracq built a special car to beat the world speed record, they came up with two racing car engines built on camshaft. The result was an engine with a displacement of 1,551 cu in, 200 bhp. Victor Hemery achieved the record on 30 December 1905 with a speed of 109.65 mph. This car still exists. Rolls-Royce built a 3,535 cc V8 car from 1905 to 1906, but only three copies were made and Rolls-Royce reverted to a I6 design. In 1907, the Hewitt Motor Company built a large five-passenger Touring Car, it was equipped with a V8 engine that developed 50/60 horsepower and had a bore of 4 in and a stroke of 4.5 in. The Hewitt was the first American automobile to be equipped with a V8 engine.
De Dion-Bouton introduced a 7,773 cc automobile V8 in 1910 and displayed it in New York in 1912. It inspired a number of manufacturers to follow suit; the limiting factor in mass production and sales of V8s was the difficulty in starting large engines using a hand crank. Not only does increasing the size of the engine make this harder, the number of pistons is a factor, because with a 4 cylinder engine, a piston comes into compression every half turn of the crank, overcoming this with the crank is not difficult. With eight cylinders, there is only 1/4 of a turn of the crank before another cylinder comes into compression. To overcome this problem, electric starters were developed; the first marque to equip its cars with electric starter motors was Cadillac, in 1912, Cadillac was the first production automobile with V8s, introduced 2 years later. It sold 13,000 of the 5.4 L L-head engines in its first year of production, 1914. Cadillac has been a V8 company since. Oldsmobile, another division of General Motors, introduced its own 4 L V8 engine in 1916.
Chevrolet introduced a 4.7 L V8 engine in 1917 and installed in the Chevrolet Series D. In February 1915, Swiss automotive engineer Marc Birkigt designed the first example of the famous Hispano-Suiza V8 single overhead cam aviation engines, in differing displacements, using dual ignition systems and in power levels from 150 horsepower to around 300 horsepower, in both direct-drive and geared output shaft versions. 50,000 of these engines were built in Spain, the United Kingdom, Italy. Wright Aeronautical built them in the United States during World War I, with the French-produced versions getting almost-exclusive use to power the SPAD S. VII and SPAD S. XIII fighter aircraft. E.5 fighters and Sopwith Dolphin fighters. The H. S. 8-series overhead cam valvetrain V8 aviation engines are said to have powered half of all Allied aircraft of the WW I era. By 1932, Henry Ford introduced one of his last great personal engineering triumphs: his "en block", or one piece, V8 engine, its simple design made possible the greatest production V8 to the masses.
Offered as an option to an improved 4-cylinder Mo
24 Hours of Le Mans
The 24 Hours of Le Mans is the world's oldest active sports car race in endurance racing, held annually since 1923 near the town of Le Mans, France. It is considered one of the most prestigious automobile races in the world and has been called the "Grand Prix of Endurance and Efficiency"; the event represents one leg of the Triple Crown of Motorsport. The race is organized by the Automobile Club de l'Ouest and is held on the Circuit de la Sarthe, which contains a mix of closed public roads and dedicated sections of racing track, in which racing teams must balance the demands of speed with the cars' ability to run for 24 hours without mechanical failure. Of the 60 cars which qualified for the 2018 race, 41 cars ran the full duration. Since 2012, the 24 Hours of Le Mans has been a part of the FIA World Endurance Championship; because of the decision to run a World Endurance Championship super-season in the period May 2018 to June 2019, the 24 Hours of Le Mans will be run twice in the same season: it will be both the second and the last round of the season.
In 2011 it was a part of the Intercontinental Le Mans Cup, it formed a part of the World Sportscar Championship from 1953 until that series' final season in 1992. Over time, Le Mans has influenced events that have sprung up all around the globe, popularizing the 24-hour format at locations such as Daytona, Nürburgring, Spa-Francorchamps, Bathurst; the American Le Mans Series and Europe's Le Mans Series of multi-event sports car championships were spun off from 24 Hours of Le Mans regulations. Other races include the Le Mans Classic, a race for historic Le Mans race cars from years' past held on the Circuit de la Sarthe, a motorcycle version of the race, held on the shortened Bugatti version of the same circuit, a kart race, a truck race, a parody race 24 Hours of LeMons; the 2019 24 Hours of Le Mans will be held on June 15–16 at the Circuit de la Sarthe, Le Mans, France. At a time when Grand Prix motor racing was the dominant form of motorsport throughout Europe, Le Mans was designed to present a different test.
Instead of focusing on the ability of a car company to build the fastest machines, the 24 Hours of Le Mans would instead concentrate on the ability of manufacturers to build sporty yet reliable cars. This encouraged innovation in producing reliable and fuel-efficient vehicles, because endurance racing requires cars that last and spend as little time in the pits as possible. At the same time, the layout of the track necessitated cars with better aerodynamics and stability at high speeds. While this was shared with Grand Prix racing, few tracks in Europe had straights of a length comparable to the Mulsanne. Additionally, because the road is public and thus not as meticulously maintained as permanent racing circuits, racing puts more strain on the parts, increasing the importance of reliability; the oil crisis in the early 1970s led organizers to adopt a fuel economy formula known as Group C that limited the amount of fuel each car was allowed. Although it was abandoned, fuel economy remains important as new fuel sources reduce time spent during pit stops.
Such technological innovations have had a trickle-down effect and can be incorporated into consumer cars. This has led to faster and more exotic supercars as manufacturers seek to develop faster road cars in order to develop them into faster GT cars. Additionally, in recent years hybrid systems have been championed in the LMP category as rules have been changed to their benefit and to further push efficiency; the race is held in June, leading at times to hot conditions for drivers in closed vehicles with poor ventilation. The race begins in mid-afternoon and finishes the following day at the same hour the race started the previous day. Over the 24 hours, modern competitors cover distances well over 5,000 km; the record is 2010's 5,410 km, six times the length of the Indianapolis 500, or 18 times longer than a Formula One Grand Prix. Drivers and racing teams strive for speed and avoiding mechanical damage, as well as managing the cars' consumables fuel and braking materials, it tests endurance, with drivers racing for over two hours before a relief driver can take over during a pit stop while they eat and rest.
Current regulations mandate. Competing teams race in groups called "classes", or cars of similar specification, while competing for outright placing amongst all classes; the race showcased cars as they were sold to the general public called "Sports Cars", in contrast with the specialised racing cars used in Grand Prix motor racing. Over time, the competing vehicles evolved away from their publicly available road car roots, today the race is made of two overall classes: prototypes, Grand Touring cars; these are further broken down into 2 sub-classes each, constructors' prototypes, privateer prototypes and 2 subclasses of GT cars. Competing teams have had a wide variety of organization, ranging from competition departments of road car manufacturers to professional motor racing teams to amateur teams; the race has spent long periods as a round of the World S
Formula One
Formula One is the highest class of single-seater auto racing sanctioned by the Fédération Internationale de l'Automobile and owned by the Formula One Group. The FIA Formula One World Championship has been one of the premier forms of racing around the world since its inaugural season in 1950; the word "formula" in the name refers to the set of rules to which all participants' cars must conform. A Formula One season consists of a series of races, known as Grands Prix, which take place worldwide on purpose-built circuits and on public roads; the results of each race are evaluated using a points system to determine two annual World Championships: one for drivers, the other for constructors. Drivers must hold valid Super Licences, the highest class of racing licence issued by the FIA; the races must run on tracks graded "1", the highest grade-rating issued by the FIA. Most events occur in rural locations on purpose-built tracks, but several events take place on city streets. Formula One cars are the fastest regulated road-course racing cars in the world, owing to high cornering speeds achieved through the generation of large amounts of aerodynamic downforce.
The cars underwent major changes in 2017, allowing wider front and rear wings, wider tyres, resulting in cornering forces closing in on 6.5g and top speeds of up to 375 km/h. As of 2019 the hybrid engines are limited in performance to a maximum of 15,000 rpm and the cars are dependent on electronics—although traction control and other driving aids have been banned since 2008—and on aerodynamics and tyres. While Europe is the sport's traditional base, the championship operates globally, with 11 of the 21 races in the 2018 season taking place outside Europe. With the annual cost of running a mid-tier team—designing and maintaining cars, transport—being US$120 million, Formula One has a significant economic and job-creation effect, its financial and political battles are reported, its high profile and popularity have created a major merchandising environment, which has resulted in large investments from sponsors and budgets. On 8 September 2016 Bloomberg reported that Liberty Media had agreed to buy Delta Topco, the company that controls Formula One, from private-equity firm CVC Capital Partners for $4.4 billion in cash and convertible debt.
On 23 January 2017 Liberty Media confirmed the completion of the acquisition for $8 billion. The Formula One series originated with the European Grand Prix Motor Racing of the 1930s; the formula is a set of rules. Formula One was a new formula agreed upon after World War II during 1946, with the first non-championship races being held that year. A number of Grand Prix racing organisations had laid out rules for a world championship before the war, but due to the suspension of racing during the conflict, the World Drivers' Championship was not formalised until 1947; the first world championship race was held at Silverstone, United Kingdom in 1950. A championship for constructors followed in 1958. National championships existed in the UK in the 1960s and 1970s. Non-championship Formula One events were held for many years, but due to the increasing cost of competition, the last of these occurred in 1983. On 26 November 2017, Formula One unveiled its new logo, following the 2017 season finale in Abu Dhabi during the Abu Dhabi Grand Prix at Yas Marina Circuit.
The new logo replaced F1's iconic'flying one', the sport's trademark since 1993. After a hiatus in European motor racing brought about by the outbreak of World War II in 1939, the first World Championship for Drivers was won by Italian Giuseppe Farina in his Alfa Romeo in 1950, narrowly defeating his Argentine teammate Juan Manuel Fangio. However, Fangio won the title in 1951, 1954, 1955, 1956, 1957, his streak interrupted by two-time champion Alberto Ascari of Ferrari. Although the UK's Stirling Moss was able to compete he was never able to win the world championship, is now considered to be the greatest driver never to have won the title. Fangio, however, is remembered for dominating Formula One's first decade and has long been considered the "Grand Master" of Formula One; this period featured teams managed by road car manufacturers Alfa Romeo, Mercedes-Benz, Maserati. The first seasons were run using pre-war cars like Alfa's 158, they were front-engined, with narrow tyres and 1.5-litre supercharged or 4.5-litre aspirated engines.
The 1952 and 1953 World Championships were run to Formula Two regulations, for smaller, less powerful cars, due to concerns over the paucity of Formula One cars available. When a new Formula One, for engines limited to 2.5 litres, was reinstated to the world championship for 1954, Mercedes-Benz introduced the advanced W196, which featured innovations such as desmodromic valves and fuel injection as well as enclosed streamlined bodywork. Mercedes drivers won the championship for two years, before the team withdrew from all motorsport in the wake of the 1955 Le Mans disaster. An era of British dominance was ushered in by Mike Hawthorn and Vanwall's championship wins in 1958, although Stirling Moss had been at the forefront of the sport without securing the world title. Between Hawthorn, Jim Clark, Jackie Stewart, John Surtees and Graham Hill, British drivers won nine Drivers' Championships and British teams won fourteen Constructors' Championsh
Phil Hill
Philip Toll Hill Jr. was an American automobile racer and the only American-born driver to win the Formula One World Drivers' Championship. He scored three wins at each of the 24 Hours of Le Mans and 12 Hours of Sebring sports car races. Hill once said, "I'm in the wrong business. I don't want to beat anybody, I don't want to be the big hero. I'm a peace-loving man, basically." Born in Miami, Hill was raised in Santa Monica, where he lived until his death. He studied business administration at the University of Southern California from 1945 to 1947, where he was a member of the Kappa Sigma fraternity. Hill left early working as a mechanic on other drivers' cars. Hill began racing cars at an early age, going to England as a Jaguar trainee in 1949 and signing with Enzo Ferrari's team in 1956, he made his debut in the French Grand Prix at Reims France in 1958 driving a Maserati. That same year, paired with Belgian teammate Olivier Gendebien, Hill became the first American-born winner of the 24 Hours of Le Mans with Hill driving most of the night in horrific rainy conditions.
He and Gendebien would go on to win the famous endurance race again in 1961 and 1962. Hill began driving full-time for the Ferrari Formula One team in 1959, earning three podium finishes and fourth place in the Drivers' Championship. In 1960 he won the Italian Grand Prix at Monza, the first Grand Prix win for an American driver in nearly forty years, since Jimmy Murphy won the 1921 French Grand Prix; this turned out to be the last win for a front-engined car in Formula 1. The following season, Hill won the Belgian Grand Prix and with two races left trailed only his Ferrari teammate Wolfgang von Trips in the season standings. A crash during the Italian Grand Prix killed fourteen spectators. Hill won the race and clinched the championship but the triumph was bittersweet. Ferrari's decision not to travel to America for the season's final round deprived Hill of the opportunity to participate in his home race at Watkins Glen as the newly crowned World Champion; when he returned for the following season, his last with Ferrari, Hill said, "I no longer have as much need to race, to win.
I don't have as much hunger anymore. I am no longer willing to risk killing myself." After leaving Ferrari at the end of 1962, he and fellow driver Giancarlo Baghetti started for the new team ATS created by ex-Ferrari engineers in the great walkout of 1961. In 1964 Hill continued in Formula One, driving for the Cooper Formula One Team before retiring from single-seaters at the end of the season and limiting his future driving to sports car racing with Ford Motor Company and the Chaparral Cars of Jim Hall. During the 1966 Formula One season, Hill participated in race weekends behind the wheel of a Ford GT40 prototype, accompanied by a remote-control Panasonic camera in order to produce images for the movie Grand Prix. In that same season, he entered his last Formula One race, the Italian Grand Prix at Monza, racing for Dan Gurney's All American Racers, but he failed to qualify. Hill retired from racing altogether in 1967. Hill has the distinction of having won the first and last races of his driving career, the final victory driving for Chaparral in the BOAC 500 at Brands Hatch in England in 1967.
Hill drove an experimental MG, EX-181, at Bonneville Salt Flats. The "Roaring Raindrop" had a 91-cubic-inch supercharged MGA twin cam engine, using 86% methanol with nitrobenzene and sulphuric ether, for an output of 290 HP. In 1959 Hill attained 257 mph in this car, breaking the previous record of Stirling Moss in the same car, 246 mph. Following his retirement, Hill built up an award-winning classic car restoration business in the 1970s called Hill & Vaughn with business partner Ken Vaughn, until they sold the partnership to Jordanian Raja Gargour and Vaughn went on to run a separate business on his own in 1984. Hill remained with Gargour at Hill & Vaughn until the sale of the business again in 1995. Hill worked as a television commentator for ABC's Wide World of Sports. Hill had a distinguished association with Road & Track magazine, he wrote several articles for them, including road tests and retrospective articles on historic cars and races. He shared his "grand old man" status at R&T with 1960s racing rival Paul Frère, who died in 2008.
Hill, in his last years, devoted his time to his vintage car collection and judged at the Pebble Beach Concours d'Elegance more than any other individual. Hill was married to Alma, had three children: Derek and Jennifer. Derek raced in International Formula 3000 in 2001, 2002 and 2003, but was forced to retire when Phil became ill with Parkinson's disease. After traveling to the Monterey Historic Automobile Races in August 2008, Hill was taken to Community Hospital of the Monterey Peninsula, where he died after a short illness from complications of Parkinson's disease in Monterey, California, on August 28. In 1991, he was inducted into the International Motorsports Hall of Fame, he was inducted in the Motorsports Hall of Fame of America as the sole sports cars driver in the inaugural 1989 class. Primary career victories: 24 Hours of Le Mans: 1958, 1961, 1962 12 Hours of Sebring: 1958, 1959, 1961 1000 km Buenos Aires: 1958, 1960 1000 km Nürburgring: 1962, 1966 F1 Italian Grand Prix: 1960, 1961 F1 Belgian Grand Prix: 1961 BOAC 500 (Bra
Manual transmission
A manual transmission known as a manual gearbox, a standard transmission or colloquially in some countries as a stick shift, is a type of transmission used in motor vehicle applications. It uses a driver-operated clutch engaged and disengaged by a foot pedal or hand lever, for regulating torque transfer from the engine to the transmission. A conventional 5-speed manual transmission is the standard equipment in a base-model vehicle, while more expensive manual vehicles are equipped with a 6-speed transmission instead; the number of forward gear ratios is expressed for automatic transmissions as well. Manual transmissions feature a driver-operated clutch and a movable gear stick. Most automobile manual transmissions allow the driver to select any forward gear ratio at any time, but some, such as those mounted on motorcycles and some types of racing cars, only allow the driver to select the next-higher or next-lower gear; this type of transmission is sometimes called a sequential manual transmission.
In a manual transmission, the flywheel is attached to the engine's crankshaft and spins along with it. The clutch disc is in between the pressure plate and the flywheel, is held against the flywheel under pressure from the pressure plate; when the engine is running and the clutch is engaged, the flywheel spins the clutch plate and hence the transmission. As the clutch pedal is depressed, the throw out bearing is activated, which causes the pressure plate to stop applying pressure to the clutch disk; this makes the clutch plate stop receiving power from the engine, so that the gear can be shifted without damaging the transmission. When the clutch pedal is released, the throw out bearing is deactivated, the clutch disk is again held against the flywheel, allowing it to start receiving power from the engine. Manual transmissions are characterized by gear ratios that are selectable by locking selected gear pairs to the output shaft inside the transmission. Conversely, most automatic transmissions feature epicyclic gearing controlled by brake bands and/or clutch packs to select gear ratio.
Automatic transmissions that allow the driver to manually select the current gear are called manumatics. A manual-style transmission operated by computer is called an automated transmission rather than an automatic though no distinction between the two terms need be made. Contemporary automobile manual transmissions use four to six forward gear ratios and one reverse gear, although consumer automobile manual transmissions have been built with as few as two and as many as seven gears. Transmissions for heavy trucks and other heavy equipment have 8 to 25 gears so the transmission can offer both a wide range of gears and close gear ratios to keep the engine running in the power band. Operating aforementioned transmissions use the same pattern of shifter movement with a single or multiple switches to engage the next sequence of gear selection. French inventors Louis-Rene Panhard and Emile Levassor are credited with the development of the first modern manual transmission, they demonstrated their three-speed transmission in 1894 and the basic design is still the starting point for most contemporary manual transmissions.
This type of transmission offered multiple gear ratios and, in most cases, reverse. The gears were engaged by sliding them on their shafts, which required careful timing and throttle manipulation when shifting, so the gears would be spinning at the same speed when engaged; these transmissions are called sliding mesh transmissions or sometimes crash boxes, because of the difficulty in changing gears and the loud grinding sound that accompanied. Newer manual transmissions on 4+-wheeled vehicles have all gears mesh at all times and are referred to as constant-mesh transmissions, with "synchro-mesh" being a further refinement of the constant mesh principle. In both types, a particular gear combination can only be engaged when the two parts to engage are at the same speed. To shift to a higher gear, the transmission is put in neutral and the engine allowed to slow down until the transmission parts for the next gear are at a proper speed to engage; the vehicle slows while in neutral and that slows other transmission parts, so the time in neutral depends on the grade and other such factors.
To shift to a lower gear, the transmission is put in neutral and the throttle is used to speed up the engine and thus the relevant transmission parts, to match speeds for engaging the next lower gear. For both upshifts and downshifts, the clutch is released; some drivers use the clutch only for starting from a stop, shifts are done without the clutch. Other drivers will depress the clutch, shift to neutral engage the clutch momentarily to force transmission parts to match the engine speed depress the clutch again to shift to the next gear, a process called double clutching. Double clutching is easier to get smooth, as speeds that are close but not quite matched need to speed up or slow down only transmission parts, whereas with the clutch engaged to the engine, mismatched speeds are fighting the rotational inertia and power of the engine. Though automobile and light truck transmissions are now universally synchronized, transmissions for heavy trucks and machinery, motor
S-segment
S-segment is the a European segments for passenger cars for sport coupés. The cars are described as sports cars and the equivalent Euro NCAP class is called "roadster sport". S-segment cars have a sporting appearance and are designed to have superior handling and/or straight-line acceleration compared to other segments; the most common body styles for S-segment cars are convertible. Rear passenger accommodation is not a priority for S-segment cars, therefore many models are either two-seat cars or have a 2+2 layout with cramped rear seating. Most recent S-segment cars use the commonplace front-engine design, however the majority of cars with a Mid-engine design or rear-engine design belong to the S-segment; the five highest selling S-segment cars in Europe are the Audi TT, Mazda MX-5, Porsche 911, Ford Mustang and Porsche Boxster/Cayman. In 2014, the five highest selling coupé models were the BMW 4 Series, Opel Astra GTC,BMW 2 Series, Renault Mégane Coupé and Mercedes-Benz C-Class; the five highest selling convertible models in 2014 were the Fiat 500C, Mini Hatch, BMW 4 Series, Volkswagen Beetle and Volkswagen Golf Mk6
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