Automotive design
Automotive design is the process of developing the appearance, to some extent the ergonomics, of motor vehicles, including automobiles, trucks, buses and vans. The functional design and development of a modern motor vehicle is done by a large team from many different disciplines included within automotive engineering, design roles are not associated with requirements for Professional or Chartered-Engineer qualifications. Automotive design in this context is concerned with developing the visual appearance or aesthetics of the vehicle, though it is involved in the creation of the product concept. Automotive design as a professional vocation is practiced by designers who may have an art background and a degree in industrial design or transportation design. Terminology used in the field is found in the glossary of automotive design; the task of the design team is split into three main aspects: exterior design, interior design, color and trim design. Graphic design is an aspect of automotive design.
Design focuses not only on the isolated outer shape of automobile parts, but concentrates on the combination of form and function, starting from the vehicle package. The aesthetic value will need to correspond to ergonomic utility features as well. In particular, vehicular electronic components and parts will give more challenges to automotive designers who are required to update on the latest information and knowledge associated with emerging vehicular gadgetry dashtop mobile devices, like GPS navigation, satellite radio, HD radio, mobile TV, MP3 players, video playback, smartphone interfaces. Though not all the new vehicular gadgets are to be designated as factory standard items, some of them may be integral to determining the future course of any specific vehicular models; the designer responsible for the exterior of the vehicle develops the proportions and surfaces of the vehicle. Exterior design is first done by a series of manual drawings. Progressively, drawings that are more detailed are executed and approved by appropriate layers of management.
Industrial plasticine and or digital models are developed from, along with the drawings. The data from these models are used to create a full-sized mock-up of the final design. With three- and five-axis CNC milling machines, the clay model is first designed in a computer program and "carved" using the machine and large amounts of clay. In times of high-class 3d software and virtual models on power walls, the clay model is still the most important tool to evaluate the design of a car and, therefore, is used throughout the industry; the designer responsible for the vehicles' interior develops the proportions, shape and surfaces for the instrument panel, door trim panels, pillar trims, etc. Here the emphasis is on the comfort of the passengers; the procedure here is the same as with exterior design. The color and trim designer is responsible for the research and development of all interior and exterior colors and materials used on a vehicle; these include paints, fabric designs, grains, headliner, wood trim, so on.
Color, contrast and pattern must be combined to give the vehicle a unique interior environment experience. Designers work with the exterior and interior designers. Designers draw inspiration from other design disciplines such as: industrial design, home furnishing and sometimes product design. Specific research is done into global trends to design for projects two to three model years in the future. Trend boards are created from this research in order to keep track of design influences as they relate to the automotive industry; the designer uses this information to develop themes and concepts that are further refined and tested on the vehicle models. The design team develops graphics for items such as: badges, dials, kick or tread strips, liveries; the sketches and rendering are transformed into 3D Digital surface modelling and rendering for real-time evaluation with Math data in initial stages. During the development process succeeding phases will require the 3D model developed to meet the aesthetic requirements of a designer and well as all engineering and manufacturing requirements.
The developed CAS digital model will be re-developed for manufacturing meeting the Class-A surface standards that involves both technical as well as aesthetics. This data will be further developed by Product Engineering team; these modelers have a background in Industrial design or sometimes tooling engineering in case of some Class-A modelers. Autodesk Alias and ICEM Surf are the two most used software tools for Class-A development. Several manufacturers have varied development cycles for designing an Automobile, but in practice these are the following. Design and User Research Concept Development sketching CAS Clay modeling Interior Buck Model Vehicle ergonomics Class-A Surface Development Colour and Trim Vehicle GraphicsThe design process occurs concurrently with other product Engineers who will be engineering the styling data for meeting performance and safety regulations. From mid-phase and forth interactions between the designers and product engineers culminates into a finished product be manufacturing ready.
Apart from this the Engineering team parallelly works in the following areas. Product Engineering, NVH Development team, Prototype
Coupé
A coupé or coupe is a two-door car with a fixed roof. In the 21st century there are four-door cars with a coupé-like roofline sold as "four door coupés" or "quad coupés". Coupé was first applied to horse-drawn carriages for two passengers without rear-facing seats; the coupé name is a French language word, the past participle of the verb couper, translating as cut. There are two common pronunciations in English: koo-PAY, the anglicized version of the French pronunciation of coupé. KOOP in American English, due to people spelling the word without the acute accent, which resulted in them pronouncing it as one syllable; this change occurred and before World War II. This pronunciation is more common in the United States, for example the hot rodders' term Deuce Coupe used to refer to a 1932 Ford; the origin of the coupé body style come from the berline horse-drawn carriage. In the 18th century, the coupé version of the berline was introduced, a shortened version with no rear-facing seat. A coupé had a fixed glass window in the front of the passenger compartment.
The term "berline coupé" was shortened to "coupé". The coupé was considered to be an ideal vehicle for women to use to go shopping or to make social visits; the early coupé automobile's passenger compartment followed in general conception the design of horse-drawn coupés, with the driver in the open at the front and an enclosure behind him for two passengers on one bench seat. The French variant for this word thus denoted a car with a small passenger compartment. By the 1910s, the term had evolved to denote a two-door car with the driver and up to two passengers in an enclosure with a single bench seat; the coupé de ville, or coupé chauffeur, was an exception, retaining the open driver's section at front. In 1916, the Society of Automobile Engineers suggested nomenclature for car bodies that included the following: Coupe: An enclosed car operated from the inside with seats for two or three and sometimes a backward-facing fourth seat. Coupelet: A small car seating two or three with a folding top and full height doors with retractable windows.
Convertible coupe: A roadster with a removable coupé roof. During the 20th century, the term coupé was applied to various close-coupled cars. Since the 1960s the term coupé has referred to a two-door car with a fixed roof. Since 2005, several models with four doors have been marketed as "four-door coupés", however reactions are mixed about whether these models are sedans instead of coupés. According to Edmunds, the American online resource for automotive information, "the four-door coupe category doesn't exist." A coupé is a two-door fixed roof car but some manufacturers manage to fit four doors beneath coupe roofs and now describe these cars as four-door coupes. In 1977, International Standard ISO 3833-1977 defined a coupé as having a closed body with limited rear volume, a fixed roof of which a portion may be openable, at least two seats in at least one row, two side doors and a rear opening, at least two side windows. Coupés have been described as "any two-door other than a two-door sedan, smaller than a related four-door in the same model line", "shorter than a sedan of the same model" and that "all two-door two-seaters with a solid roof are coupes."Today, coupé is sometimes used by manufacturers as a marketing term, rather than a technical description of a body style.
This is because coupés in general are seen as more streamlined and sportier overall lines than those of comparable four-door sedans. Automobile manufacturers have therefore begun to use the term loosely, marketing sporty four-door models that feature sloping rooflines as coupés. Manufacturers have used the term "coupé" with reference to several varieties, including: A Berlinetta is a lightweight sporty two-door car with two-seats but including 2+2 cars. A two-door car with no rear seat or with a removable rear seat intended for travelling salespeople and other vendors carrying their wares with them. American manufacturers developed this style of coupe in the late 1930s. A two-door car with a larger rear-seat passenger area, compared with the smaller rear-seat area in a 2+2 body style. Saab uses the term combi coupé for a car body similar to the liftback. A four-door car with a coupé-like roofline at the rear; the low-roof design reduces headroom. The designation, first applied to a low-roof model of the Rover P5 from 1962 until 1973, was revived with the 1985 Toyota Carina ED, the 1992 Infiniti J30 and most with the first model 2005 Mercedes-Benz CLS.
The term originated for marketing reasons. The German press accepted the concept of a four-door coupé and applied it to similar models from other manufacturers such as the 2009 Jaguar XJ. Other manufacturers accepted it, producing recent competing models like Volkswagen Passat CC, BMW F06 and a five-door coupé, the Audi A7; the German automobile club ADAC on its website adopted this concept. In Germany, the definition of the coupé was divided into the classic coupé and 4-door coupé. A two-door designed for driving to the opera with easy access to the rear seats. Features sometimes included a folding front seat next to the driver or a compartment to store top hats, they would have solid rear-quarter panels, with small, circular windows, to enable the occupants to see out without being seen. These opera windows were revived on many U. S. automobiles during the 1970s and early 1980s. A quad coupé is two small rear doors and no B pillar; the three window coupé (commonly jus
Transmission (mechanics)
A transmission is a machine in a power transmission system, which provides controlled application of the power. The term transmission refers to the gearbox that uses gears and gear trains to provide speed and torque conversions from a rotating power source to another device. In British English, the term transmission refers to the whole drivetrain, including clutch, prop shaft and final drive shafts. In American English, the term refers more to the gearbox alone, detailed usage differs; the most common use is in motor vehicles, where the transmission adapts the output of the internal combustion engine to the drive wheels. Such engines need to operate at a high rotational speed, inappropriate for starting and slower travel; the transmission reduces the higher engine speed to the slower wheel speed, increasing torque in the process. Transmissions are used on pedal bicycles, fixed machines, where different rotational speeds and torques are adapted. A transmission has multiple gear ratios with the ability to switch between them as speed varies.
This switching may be done automatically. Directional control may be provided. Single-ratio transmissions exist, which change the speed and torque of motor output. In motor vehicles, the transmission is connected to the engine crankshaft via a flywheel or clutch or fluid coupling because internal combustion engines cannot run below a particular speed; the output of the transmission is transmitted via the driveshaft to one or more differentials, which drives the wheels. While a differential may provide gear reduction, its primary purpose is to permit the wheels at either end of an axle to rotate at different speeds as it changes the direction of rotation. Conventional gear/belt transmissions are not the only mechanism for speed/torque adaptation. Alternative mechanisms include power transformation. Hybrid configurations exist. Automatic transmissions use a valve body to shift gears using fluid pressures in response to speed and throttle input. Early transmissions included the right-angle drives and other gearing in windmills, horse-powered devices, steam engines, in support of pumping and hoisting.
Most modern gearboxes are used to increase torque while reducing the speed of a prime mover output shaft. This means that the output shaft of a gearbox rotates at a slower rate than the input shaft, this reduction in speed produces a mechanical advantage, increasing torque. A gearbox can be set up to do the opposite and provide an increase in shaft speed with a reduction of torque; some of the simplest gearboxes change the physical rotational direction of power transmission. Many typical automobile transmissions include the ability to select one of several gear ratios. In this case, most of the gear ratios are used to slow down the output speed of the engine and increase torque. However, the highest gears may be "overdrive" types. Gearboxes have found use in a wide variety of different—often stationary—applications, such as wind turbines. Transmissions are used in agricultural, construction and automotive equipment. In addition to ordinary transmission equipped with gears, such equipment makes extensive use of the hydrostatic drive and electrical adjustable-speed drives.
The simplest transmissions called gearboxes to reflect their simplicity, provide gear reduction, sometimes in conjunction with a right-angle change in direction of the shaft. These are used on PTO-powered agricultural equipment, since the axial PTO shaft is at odds with the usual need for the driven shaft, either vertical, or horizontally extending from one side of the implement to another. More complex equipment, such as silage choppers and snowblowers, have drives with outputs in more than one direction; the gearbox in a wind turbine converts the slow, high-torque rotation of the turbine into much faster rotation of the electrical generator. These are more complicated than the PTO gearboxes in farm equipment, they weigh several tons and contain three stages to achieve an overall gear ratio from 40:1 to over 100:1, depending on the size of the turbine. The first stage of the gearbox is a planetary gear, for compactness, to distribute the enormous torque of the turbine over more teeth of the low-speed shaft.
Durability of these gearboxes has been a serious problem for a long time. Regardless of where they are used, these simple transmissions all share an important feature: the gear ratio cannot be changed during use, it is fixed at the time. For transmission types that overcome this issue, see Continuously variable transmission known as CVT. Many applications require the availability of multiple gear ratios; this is to ease the starting and stopping of a mechanical system, though another important need is that of maintaining good fuel efficiency. The need for a transmission in an automobile is a consequence of the characteristics of the internal combustion engine. Eng
Electric motor
An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of rotation of a shaft. Electric motors can be powered by direct current sources, such as from batteries, motor vehicles or rectifiers, or by alternating current sources, such as a power grid, inverters or electrical generators. An electric generator is mechanically identical to an electric motor, but operates in the reverse direction, converting mechanical energy into electrical energy. Electric motors may be classified by considerations such as power source type, internal construction and type of motion output. In addition to AC versus DC types, motors may be brushed or brushless, may be of various phase, may be either air-cooled or liquid-cooled. General-purpose motors with standard dimensions and characteristics provide convenient mechanical power for industrial use.
The largest electric motors are used for ship propulsion, pipeline compression and pumped-storage applications with ratings reaching 100 megawatts. Electric motors are found in industrial fans and pumps, machine tools, household appliances, power tools and disk drives. Small motors may be found in electric watches. In certain applications, such as in regenerative braking with traction motors, electric motors can be used in reverse as generators to recover energy that might otherwise be lost as heat and friction. Electric motors produce linear or rotary force and can be distinguished from devices such as magnetic solenoids and loudspeakers that convert electricity into motion but do not generate usable mechanical force, which are referred to as actuators and transducers; the first electric motors were simple electrostatic devices described in experiments by Scottish monk Andrew Gordon and American experimenter Benjamin Franklin in the 1740s. The theoretical principle behind them, Coulomb's law, was discovered but not published, by Henry Cavendish in 1771.
This law was discovered independently by Charles-Augustin de Coulomb in 1785, who published it so that it is now known with his name. The invention of the electrochemical battery by Alessandro Volta in 1799 made possible the production of persistent electric currents. After the discovery of the interaction between such a current and a magnetic field, namely the electromagnetic interaction by Hans Christian Ørsted in 1820 much progress was soon made, it only took a few weeks for André-Marie Ampère to develop the first formulation of the electromagnetic interaction and present the Ampère's force law, that described the production of mechanical force by the interaction of an electric current and a magnetic field. The first demonstration of the effect with a rotary motion was given by Michael Faraday in 1821. A free-hanging wire was dipped into a pool of mercury; when a current was passed through the wire, the wire rotated around the magnet, showing that the current gave rise to a close circular magnetic field around the wire.
This motor is demonstrated in physics experiments, substituting brine for mercury. Barlow's wheel was an early refinement to this Faraday demonstration, although these and similar homopolar motors remained unsuited to practical application until late in the century. In 1827, Hungarian physicist Ányos Jedlik started experimenting with electromagnetic coils. After Jedlik solved the technical problems of continuous rotation with the invention of the commutator, he called his early devices "electromagnetic self-rotors". Although they were used only for teaching, in 1828 Jedlik demonstrated the first device to contain the three main components of practical DC motors: the stator and commutator; the device employed no permanent magnets, as the magnetic fields of both the stationary and revolving components were produced by the currents flowing through their windings. After many other more or less successful attempts with weak rotating and reciprocating apparatus Prussian Moritz von Jacobi created the first real rotating electric motor in May 1834.
It developed remarkable mechanical output power. His motor set a world record, which Jacobi improved four years in September 1838, his second motor was powerful enough to drive a boat with 14 people across a wide river. It was in 1839/40 that other developers managed to build motors with similar and higher performance; the first commutator DC electric motor capable of turning machinery was invented by British scientist William Sturgeon in 1832. Following Sturgeon's work, a commutator-type direct-current electric motor was built by American inventor Thomas Davenport, which he patented in 1837; the motors ran at up to 600 revolutions per minute, powered machine tools and a printing press. Due to the high cost of primary battery power, the motors were commercially unsuccessful and bankrupted Davenport. Several inventors followed Sturgeon in the development of DC motors, but all encountered the same battery cost issues; as no electricity distribution system was available at the time, no practical commercial market emerged for these motors.
In 1855, Jedlik built a device using similar principles to those used in his electromagnetic self-rotors, capable of useful work. He built a model electric vehicle that same year. A major turning point came in 1864; this featured symmetrically-grouped coils closed upon themselves and connected to the bars of a commutator, the brushes of which delivered non-fluctuating current. The first c
Car classification
Governments and private organizations have developed car classification schemes that are used for various purposes including regulation and categorization, among others. This article details used classification schemes in use worldwide; this following table summarises common classifications for cars. Microcars and their Japanese equivalent— kei cars— are the smallest category of automobile. Microcars straddle the boundary between car and motorbike, are covered by separate regulations to normal cars, resulting in relaxed requirements for registration and licensing. Engine size is 700 cc or less, microcars have three or four wheels. Microcars are most popular in Europe, where they originated following World War II; the predecessors to micro cars are Cycle cars. Kei cars have been used in Japan since 1949. Examples of microcars and kei cars: Honda Life Isetta Tata Nano The smallest category of vehicles that are registered as normal cars is called A-segment in Europe, or "city car" in Europe and the United States.
The United States Environmental Protection Agency defines this category as "minicompact", however this term is not used. The equivalents of A-segment cars have been produced since the early 1920s, however the category increased in popularity in the late 1950s when the original Fiat 500 and BMC Mini were released. Examples of A-segment / city cars / minicompact cars: Fiat 500 Hyundai i10 Toyota Aygo The next larger category small cars is called B-segment Europe, supermini in the United Kingdom and subcompact in the United States; the size of a subcompact car is defined by the United States Environmental Protection Agency, as having a combined interior and cargo volume of between 85–99 cubic feet. Since the EPA's smaller minicompact category is not as used by the general public, A-segment cars are sometimes called subcompacts in the United States. In Europe and Great Britain, the B-segment and supermini categories do not any formal definitions based on size. Early supermini cars in Great Britain include Vauxhall Chevette.
In the United States, the first locally-built subcompact cars were the 1970 AMC Gremlin, Chevrolet Vega, Ford Pinto. Examples of B-segment / supermini / subcompact cars: Chevrolet Sonic Hyundai Accent Volkswagen Polo The largest category of small cars is called C-segment or small family car in Europe, compact car in the United States; the size of a compact car is defined by the United States Environmental Protection Agency, as having a combined interior and cargo volume of 100–109 cu ft. Examples of C-segment / compact / small family cars: Peugeot 308 Toyota Auris Renault Megane In Europe, the third largest category for passenger cars is called D-segment or large family car. In the United States, the equivalent term is intermediate cars; the U. S. Environmental Protection Agency defines a mid-size car as having a combined passenger and cargo volume of 110–119 cu ft. Examples of D-segment / large family / mid-size cars: Chevrolet Malibu Ford Mondeo Kia Optima In Europe, the second largest category for passenger cars is E-segment / executive car, which are luxury cars.
In other countries, the equivalent terms are full-size car or large car, which are used for affordable large cars that aren't considered luxury cars. Examples of non-luxury full-size cars: Chevrolet Impala Ford Falcon Toyota Avalon Minivan is an American car classification for vehicles which are designed to transport passengers in the rear seating row, have reconfigurable seats in two or three rows; the equivalent terms in British English are people carrier and people mover. Minivans have a'one-box' or'two-box' body configuration, a high roof, a flat floor, a sliding door for rear passengers and high H-point seating. Mini MPV is the smallest size of MPVs and the vehicles are built on the platforms of B-segment hatchback models. Examples of Mini MPVs: Fiat 500L Honda Fit Ford B-Max Compact MPV is the middle size of MPVs; the Compact MPV size class sits between large MPV size classes. Compact MPVs remain predominantly a European phenomenon, although they are built and sold in many Latin American and Asian markets.
Examples of Compact MPVs: Renault Scenic Volkswagen Touran Ford C-Max The largest size of minivans is referred to as'Large MPV' and became popular following the introduction of the 1984 Renault Espace and Dodge Caravan. Since the 1990s, the smaller Compact MPV and Mini MPV sizes of minivans have become popular. If the term'minivan' is used without specifying a size, it refers to a Large MPV. Examples of Large MPVs: Dodge Grand Caravan Ford S-Max Toyota Sienna The premium compact class is the smallest category of luxury cars, it became popular in the mid-2000s, when European manufacturers— such as Audi, BMW and Mercedes-Benz— introduced new entry level models that were smaller and cheaper than their compact executive models. Examples of premium compact cars: Audi A3 Buick Verano Lexus CT200h A compact executive car is a premium car larger than a premium compact and smaller than an executive car. Compact executive cars are equivalent size to mid-size cars and are part of the D-segment in the European car classification.
In North American terms, close equivalents are "luxury compact" and "entry-level luxury car", although the latter is used for the smaller premium compact cars. Examples of compact executive cars: Audi A4 BMW 3 Series Buick Regal An executive car is a premium car larger than a compact executive and smaller than an full-size luxury car. Executive cars are classified as E-segment cars in the European car classification. In the United States and several other coun
Sports car
A sports car, or sportscar, is a small two-seater automobile designed for spirited performance and nimble handling. The term "sports car" was used in The Times, London in 1919. According to the Merriam-Webster dictionary, USA's first known use of the term was in 1928. Sports cars started to become popular during the 1920s. Sports cars may be spartan or luxurious. Sports cars are aerodynamically shaped, have a lower center of gravity than standard models. Steering and suspension are designed for precise control at high speeds. Traditionally sports cars were open roadsters, but closed coupés started to become popular during the 1930s, the distinction between a sports car and a grand tourer is not absolute. Attributing the definition of'sports car' to any particular model can be controversial or the subject of debate among enthusiasts. Authors and experts have contributed their own ideas to capture a definition. A car may be a sporting automobile without being a sports car. Performance modifications of regular, production cars, such as sport compacts, sports sedans, muscle cars, pony cars and hot hatches are not considered sports cars, yet share traits common to sports cars.
Certain models can "appeal to both muscle car and sports car enthusiasts, two camps that acknowledged each other's existences." Some models are called "sports cars" for marketing purposes to take advantage of greater marketplace acceptance and for promotional purposes. High-performance cars of various configurations are grouped as Sports and Grand tourer cars or just as performance cars; the drivetrain and engine layout influences the handling characteristics of an automobile, is crucially important in the design of a sports car. The front-engine, rear-wheel-drive layout is common to sports cars of any era and has survived longer in sports cars than in mainstream automobiles. Examples include the Caterham 7, Mazda MX-5, the Chevrolet Corvette. More many such sports cars have a front mid-engine, rear-wheel drive layout, with the centre of mass of the engine between the front axle and the firewall. In search of improved handling and weight distribution, other layouts are sometimes used; the rear mid-engine, rear-wheel-drive layout is found only in sports cars—the motor is centre-mounted in the chassis, powers only the rear wheels.
Some high-performance sports car manufacturers, such as Ferrari and Lamborghini have preferred this layout. Porsche is one of the few remaining manufacturers using the rear-wheel-drive layout; the motor's distributed weight across the wheels, in a Porsche 911, provides excellent traction, but the significant mass behind the rear wheels makes it more prone to oversteer in some situations. Porsche has continuously refined the design and in recent years added electronic stability control to counteract these inherent design shortcomings; the front-engine, front-wheel-drive layout layout, the most common in sport compacts and hot hatches, modern production cars in general, is not used for sports cars. This layout is advantageous for small, lower power sports cars, as it avoids the extra weight, increased transmission power loss, packaging problems of a long driveshaft and longitudinal engine of FR vehicles. However, its conservative handling effect understeer, the fact that many drivers believe rear wheel drive is a more desirable layout for a sports car count against it.
The Fiat Barchetta, Saab Sonett, Berkeley cars are sports cars with this layout. Before the 1980s few sports cars used four-wheel drive, which had traditionally added a lot of weight. With its improvement in traction in adverse weather conditions, four-wheel drive is no longer uncommon in high-powered sports cars, e.g. Porsche and the Bugatti Veyron. Traditional sports cars were two-seat roadsters. Although the first sports cars were derived from fast tourers, early sporting regulations demanded four seats, two seats became common from about the mid-1920s. Modern sports cars may have small back seats that are really only suitable for luggage or small children. Over the years, some manufacturers of sports cars have sought to increase the practicality of their vehicles by increasing the seating room. One method is to place the driver's seat in the center of the car, which allows two full-sized passenger seats on each side and behind the driver; the arrangement was considered for the Lamborghini Miura, but abandoned as impractical because of the difficulty for the driver to enter/exit the vehicle.
McLaren used the design in their F1. Another British manufacturer, TVR, took a different approach in their Cerbera model; the interior was designed in such a way that the dashboard on the passenger side swept toward the front of the car, which allowed the passenger to sit farther forward than the driver. This gave the rear seat passenger extra room and made the arrangement suitable for three adult passengers and one child seated behind the driver; some Matra sports cars had three seats squeezed next to each other. The definition of a sports car is not precise, but from the earliest first automobiles "people have found ways to make them go faster, round corners better, look more beautiful" than the ordinary models inspiring an "emotional relationship" with a car, fun to drive and use for the sake of driving; the basis for the sports car is traced to the early 20th century touring cars a
V12 engine
A V12 engine is a V engine with 12 cylinders mounted on the crankcase in two banks of six cylinders each but not always at a 60° angle to each other, with all 12 pistons driving a common crankshaft. Since each cylinder bank is a straight-six, by itself in both primary and secondary balance, a V12 inherits perfect primary and secondary balance no matter which V angle is used, therefore it needs no balance shafts. A four-stroke 12 cylinder engine has an firing order if cylinders fire every 60° of crankshaft rotation, so a V12 with cylinder banks at a multiples of 60° will have firing intervals without using split crankpins. By using split crankpins or ignoring minor vibrations, any V angle is possible; the 180° configuration is referred to as a "flat-twelve engine" or a "boxer" although it is in reality a 180° V since the pistons can and do use shared crankpins. It may be written as "V-12", although this is less common; these engines deliver power pulses more than engines with six or eight cylinders, the power pulses have triple overlap which eliminates gaps between power pulses and allows for greater refinement and smoothness in a luxury car engine, at the expense of much greater cost and friction losses.
In a racing car engine, the rotating parts of a V12 can be made much lighter than a V8 of similar displacement with a crossplane crankshaft because there is no need to use heavy counterweights on the crankshaft and less need for the inertial mass in a flywheel to smooth out the power delivery, each piston can be smaller and with a shorter stroke. Exhaust system tuning is much more difficult on a crossplane V8 than a V12, so racing cars with V8 engines use a complicated "bundle of snakes" exhaust system, or a flat-plane crankshaft which causes severe engine vibration and noise; this is not important in a race car. Since cost and fuel economy are important in luxury and racing cars, the V12 has been phased out in favor of engines with fewer cylinders. Engines are designed around cylinder units of a certain designed size and speed; these are used as the working base of an engine of 6 cylinders. If more power is needed, it is easier to add more cylinders to increase displacement, without having to design a newer, larger cylinder and head for each engine size.
Thus locomotive and marine engines like the EMD 567 come in V6 to V24 versions, all sharing the same 567 cubic inch cylinder displacement and cylinder heads. Engines are limited by the size of the cylinder bore and stroke. While one can increase the size of an engine by increasing the bore and/or stroke of the cylinder, a too-large bore hurts efficient combustion, makes for a heavy reciprocating piston mass, which limits maximum engine speed and thus power output. In a similar vein, increasing the stroke means the piston speed must be increased to match the same revolutions per minute, this limits the maximum size of an engine in a given weight/size range; these factors make it more feasible to build an engine of 12 cylinders and 40 liters displacement than an engine of 6 cylinders and the same size, which would have pistons too large and a stroke too long to meet the same RPM and power requirements. In a large displacement, high-power engine, a 60° V12 fits into a longer and narrower space than a V8 and most other V configurations, a problem in modern cars, but less so in heavy trucks, a problem in large stationary engines.
The V12 is common in locomotive and tank engines, where high power is required, but the width of the engine is constrained by tight railway clearances or street widths, while the length of the vehicle is more flexible. It is used in marine engines where great power is required, the hull width is limited, but a longer vessel allows faster hull speed. In twin-propeller boats, two V12 engines can be narrow enough to sit side-by-side, while three V12 engines are sometimes used in high-speed three-propeller configurations. Large, fast cruise ships can have six or more V12 engines. In historic piston-engine fighter and bomber aircraft, the long, narrow V12 configuration used in high-performance aircraft made them more streamlined than other engines the short, wide radial engine. During World War II the power of fighter engines was stepped up to extreme levels using multi-speed superchargers and ultra-high octane gasoline, so the extreme smoothness of the V12 prevented the powerful engines from tearing apart the light airframes of fighters.
After World War II, the compact, more powerful, vibration-free turboprop and turbojet engines replaced the V12 in aircraft applications. The first V-type engine was built in 1889 to a design by Wilhelm Maybach. By 1903 V8 engines were being produced for motor boat racing by the Société Antoinette to designs by Léon Levavasseur, building on experience gained with in-line four-cylinder engines. In 1904, the Putney Motor Works completed a new V12 marine racing engine—the first V12 engine produced for any purpose. Known as the "Craig-Dörwald" engine after Putney's founding partners, the engine mounted pairs of L-head cylinders at a 90 degree included angle on an aluminium crankcase, using the same cylinder pairs that powered the company's standard two-cylinder car. A single camshaft mounted in the central V operated the valves directly; as in many marine engines, the camshaft could be slid longitudinally to engage a second set of cams, giving valve timing that reversed the engine's rotation to achieve astern propulsion.
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