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
Alfa Romeo Montreal
The Alfa Romeo Montreal is a 2+2 coupé sports car produced by the Italian manufacturer Alfa Romeo from 1970 to 1977. The Alfa Romeo Montreal was introduced as a concept car in 1967 at Expo 67, held in Montreal, Canada; the concept cars were displayed without any model name, but the public took to calling it The Montreal. It was a 2+2 coupe using the 1.6-litre engine of the Alfa Romeo Giulia TI and the short wheelbase chassis of the Alfa Romeo Giulia Sprint GT, with a body designed by Marcello Gandini at Bertone. One of the two concept cars built for Expo 67 is displayed in the Alfa Romeo Historical Museum in Arese, while the other is in museum storage; the first production car, Tipo 105.64, was shown at the 1970 Geneva Motor Show and was quite different from the original, using a 2593 cc 90° dry-sump lubricated, cross-plane V8 engine with SPICA fuel injection that produced around 200 PS, coupled to a five-speed ZF manual gearbox and a limited-slip differential. This engine was derived from the 2-litre V8 used in the 33 Stradale and in the Tipo 33 sports prototype racer.
The chassis and running gear of the production Montreal were taken from the Giulia GTV coupé and comprised double wishbone suspension with coil springs and dampers at the front and a live axle with limited slip differential at the rear. Since the concept car was unofficially known as The Montreal, Alfa Romeo kept the model name in production. Stylistically, the most eye catching feature is the car's front end with four headlamps covered by unusual "grilles", that retract when the lights are switched on. Another stylistic element is the NACA duct on the bonnet; the duct is blocked off since its purpose is not to draw air into the engine, but to optically hide the power bulge. The slats behind the doors contain the cabin vents, but apart from that only serve cosmetic purposes. Paolo Martin is credited for the prototype instrument cluster; the Montreal was more expensive to buy than the Jaguar E-Type or the Porsche 911. When launched in the UK it was priced at GB£5,077, rising to GB£5,549 in August 1972 and to GB£6,999 by mid-1976.
Production was split between the Alfa Romeo plant in Arese and Carrozzeria Bertone's plants in Caselle and Grugliasco outside Turin. Alfa Romeo produced the chassis and engine and mechanicals and sent the chassis to Caselle where Bertone fitted the body. After body fitment, the car was sent to Grugliasco to be degreased zinc coated, manually spray painted and have the interior fitted; the car was returned to Arese to have the engine and mechanicals installed. It is worth noting that because of this production method, there is not any correspondence between chassis number, engine number and production date; the Montreal remained unchanged until it was discontinued in 1977. By production had long ceased as Alfa were struggling to sell their remaining stock; the total number built was around 3900. None of them were sold in Montreal since Alfa did not develop a North American version to meet the emission control requirements in the United States & Canada. A Montreal can be seen in the 1974 movie The Marseille Contract where Michael Caine drives a metallic dark brown example.
A careful observer can find a red Montreal in the beginning of the James Cameron movie True Lies prior to the lead character saying "Here is my invitation." A Montreal is featured in the 2017 movie Atomic Blonde. Autodelta completed late in 1972 a Group 4 Montreal, it was launched at the London Racing Car Show in January 1973, it was sold to Alfa Romeo Germany to be used in the DRM series for GT cars. Ready to race in May 1973, the car was entrusted to specialist racing team of Dieter Gleich, the principle driver; the Autodelta version had 2997 cc engine with maximum power of 370 hp at 9000 rpm. Without any further development the car was outdated soon. A Montreal was campaigned in the United States but without success. Alfa Romeo 33 Stradale The Alfa Romeo Montreal Website Classic Motorsports magazine Alfa Romeo Montreal buyer's guide
An automatic transmission called auto, self-shifting transmission, n-speed automatic, or AT, is a type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually. Like other transmission systems on vehicles, it allows an internal combustion engine, best suited to run at a high rotational speed, to provide a range of speed and torque outputs necessary for vehicular travel; the number of forward gear ratios is expressed for manual transmissions as well. The most popular form found in automobiles is the hydraulic automatic transmission. Similar but larger devices are used for heavy-duty commercial and industrial vehicles and equipment; this system uses a fluid coupling in place of a friction clutch, accomplishes gear changes by hydraulically locking and unlocking a system of planetary gears. These systems have a defined set of gear ranges with a parking pawl that locks the output shaft of the transmission to keep the vehicle from rolling either forward or backward.
Some machines with limited speed ranges or fixed engine speeds, such as some forklifts and lawn mowers, only use a torque converter to provide a variable gearing of the engine to the wheels. Besides the traditional hydraulic automatic transmissions, there are other types of automated transmissions, such as a continuously variable transmission and semi-automatic transmissions, that free the driver from having to shift gears manually, by using the transmission's computer to change gear, if for example the driver were redlining the engine. Despite superficial similarity to other transmissions, traditional automatic transmissions differ in internal operation and driver's feel from semi-automatics and CVTs. In contrast to conventional automatic transmissions, a CVT uses a belt or other torque transmission scheme to allow an "infinite" number of gear ratios instead of a fixed number of gear ratios. A semi-automatic retains a clutch like a manual transmission, but controls the clutch through electrohydraulic means.
The ability to shift gears manually via paddle shifters, can be found on certain automated transmissions, semi-automatics, CVTs. The obvious advantage of an automatic transmission to the driver is the lack of a clutch pedal and manual shift pattern in normal driving; this allows the driver to operate the car with as few as two limbs, allowing individuals with disabilities to drive. The lack of manual shifting reduces the attention and workload required inside the cabin, such as monitoring the tachometer and taking a hand off the wheel to move the shifter, allowing the driver to ideally keep both hands on the wheel at all times and to focus more on the road. Control of the car at low speeds is easier with an automatic than a manual, due to a side effect of the clutchless fluid-coupling design called "creep" that causes the car to want to move while in a driving gear at idle; the primary disadvantage of the most popular hydraulic designs is reduced mechanical efficiency of the power transfer between engine and drivetrain, due to the fluid coupling connecting the engine to the gearbox.
This can result in lower power/torque ratings for automatics compared to manuals with the same engine specs, as well as reduced fuel efficiency in city driving as the engine must maintain idle against the resistance of the fluid coupling. Advances in transmission and coupler design have narrowed this gap but clutch-based transmissions are still preferred in sport-tuned trim levels of various production cars, as well as in many auto racing leagues; the automatic transmission was invented in 1921 by Alfred Horner Munro of Regina, Saskatchewan and patented under Canadian patent CA 235757 in 1923.. Being a steam engineer, Munro designed his device to use compressed air rather than hydraulic fluid, so it lacked power and never found commercial application; the first automatic transmission using hydraulic fluid may have been developed in 1932 by two Brazilian engineers, José Braz Araripe and Fernando Lehly Lemos. They were incorporated into GM-built tanks during World War II and, after the war, GM marketed them as being "battle-tested."
Modern automatic transmissions can trace their origins to an early "horseless carriage" gearbox, developed in 1904 by the Sturtevant brothers of Boston, Massachusetts. This unit had two forward speeds, the ratio change being brought about by flyweights that were driven by the engine. At higher engine speeds, high gear was engaged; as the vehicle slowed down and engine RPM decreased, the gearbox would shift back to low. The metallurgy of the time wasn't up to the task, owing to the abruptness of the gear change, the transmission would fail without warning. One of the key developments in arriving at an automatic transmission was the use of planetary transmission in the vehicle's gearbox; the first use of, in the Wilson-Pilcher made between 1900 and 1907. The Wilson-Pilcher used two epicyclic gear trains allowing 4 forward gears to be selected by moving a single gear change lever. In this form of gearbox the planetary gears are in constant mesh, all, required is to use a mechanism to fix or release the rotation of the outer gear ring.
The action of the
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
Front-engine, rear-wheel-drive layout
In automotive design, an FR, or front-engine, rear-wheel-drive layout is one where the engine is located at the front of the vehicle and driven wheels are located at the rear. This was the traditional automobile layout for most of the 20th century. Modern designs use the front-engine, front-wheel-drive layout. In automotive design, a front mid-engine, rear-wheel-drive layout is one that places the engine in the front, with the rear wheels of vehicle being driven. In contrast to the front-engine, rear-wheel-drive layout, the engine is pushed back far enough that its center of mass is to the rear of the front axle; this aids in weight distribution and reduces the moment of inertia, improving the vehicle's handling. The mechanical layout of an FMR is the same as an FR car; some models of the same vehicle can be classified as either FR or FMR depending on the length of the installed engine and its centre of mass in relation to the front axle. FMR cars are characterized by a long hood and front wheels that are pushed forward to the corners of the vehicle, close to the front bumper.
Grand tourers have FMR layouts, as a rear engine would not leave much space for the rear seats. FMR should not be confused with a "front midships" location of the engine, referring to the engine being located behind the front axle centerline, in which case a car meeting the above FMR center of mass definition could be classified as a FR layout instead; the v35 Nissan Skyline / Infiniti G35 / Nissan 350Z are FM cars. FMR layout came standard in most pre–World War II, front-engine / rear-wheel-drive cars
Alfa Romeo 6C
The Alfa Romeo 6C name was used on road and sports cars produced between 1927 and 1954 by Alfa Romeo. Bodies for these cars were made by coachbuilders such as James Young, Touring and Pininfarina. Starting from 1933 there was a 6C version with a factory Alfa body, built in Portello. In the early 1920s Vittorio Jano received a commission to create a lightweight, high performance vehicle to replace the Giuseppe Merosi designed RL and RM models; the car was introduced in April 1925 at the Salone dell' Automobile di Milano as the 6C 1500. It was based on the P2 racing car, using single overhead cam 1,487 cc in-line six-cylinder motor producing 44 horsepower, in 1928 the 1500 Sport was presented, the first Alfa Romeo road car with double overhead camshafts. In the mid-1920s, Alfa's RL was considered too large and heavy, so a new development began; the 2-liter formula that had led to Alfa Romeo winning the Automobile World Championship in 1925, changed to 1.5-liter for the 1926 season. The 6C 1500 was introduced in 1925 at the Milan Motor Show, production started 1927, with the P2 Grand Prix car as a starting point.
Engine capacity was now 1487 cc, against the P2's 1987 cc. First versions were bodied by Touring. In 1928, a 6C Sport was released, with a dual overhead camshafts engine, its sport version won many races, including the 1928 Mille Miglia. Total production was 3000. Ten copies of a supercharged Super Sport variant were made; the more powerful 6C 1750 was introduced in 1929 in Rome. The car featured a top speed of 95 mph, a chassis designed to flex and undulate over wavy surfaces, as well as sensitive geared-up steering, it was produced in six series between 1929 and 1933. The base model had a single overhead cam. Super Sport and Gran Sport versions had a double overhead cam engine. Again, a supercharger was available. Most of the cars were sold as rolling chassis and bodied by coachbuilders such as Zagato, Touring. Additionally, there were 3 examples built with James Young bodywork, one of, a part of the permanent collection at the Simeone Foundation Automotive Museum in Philadelphia, PA, USA in original, unrestored condition.
In 1929, it won every major racing event it was entered in, including the Grands Prix of Belgium, Spain and Monza, the Mille Miglia was won with Giuseppe Campari and Giulio Ramponi. The Brooklands Double Twelve and the Ulster TT were won, in 1930 it won again at the Mille Miglia and Spa 24 Hours. Total production was 2635; the 1931 6C 1750 with license plate number "3710 SV" and chassis/engine number #10814331, owned by notorious rare car collector Corrado Lopresto, is a unique exemplar, which's story is told in Lopresto's bilingual 2015 Skira book Best in Show – Capolavori dell'auto italiana dalla collezione Lopresto – Italian Cars Masterpieces from the Lopresto Collection. The English-language section about this car tells: Born with a spider body by Zagato, this car is a 6C 1750 Gran Sport with compressor, the sportiest version of the Milanese 6-cylinder, is sold new to Giovanni Battista Aldo Barabini of Genova in 1931. After several changes of ownership the car goes back to Alfa Romeo, to be resold in 1933 to Dino Carabba, who in 1934 enrolls in the Varese-Campo dei Fiori, coming in fourth in class and eleventh overall.
In those years, the 6C runs in minor races, changing hands three times before being sold to the body shop Giuseppe Aprile of Savona, in August 1938. Less than a year after, the car is purchased by Brunello Feltri of Altare, province of Savona, but meanwhile, Aprile has rebuilt the body of the car with a new modern and elegant look; the design, so well executed, indicates the work of the most famous designer of that time: Mario Revelli di Beaumont, father of this and many other beautiful bodies. The car so transformed survives the war unscathed and changes ownership again in 1956, in Liguria, where it remains still today, rediscovery yet in order, although with some modifications; the painstaking restoration work has restored it to its original splendor, as well conceived by Revelli: a unique car that blends the great elegance to the sporty temperament of mechanics. A plush version of the car, manufactured by Vitale Barberis Canonico, was given, together with the book, to some of Lopresto's friends.
The Alfa Romeo 6C 1900 was the last derivative of the original 6C 1500, produced in 197 examples during 1933, as a transitional model before the new 6C 2300 was introduced the following year. Only made in Gran Turismo guise with a 2,920 mm wheelbase, the 6C 1900 replaced the corresponding 6C 1750 model. Besides the larger displacement, other notable mechanical changes were aluminium cylinder heads, an improved frame and a new transmission; the same upgrades were applied to the 1933 model 6C 1750 Gran Sport, which together with the 6C 1900 forms the sixth series of the 6C. Alfa Romeo offered the 6C 1900 with an in-house 4-door saloon body, while bespoke coachbuilt body styles included 4-seat cabriolets; the double overhead camshaft aspirated straight-six engine was bored out from 66 mm to 68 mm, bringing displacement to 1,917 cc. For the first time on a 6C the cylinder head was aluminium. With 68 bhp at 4,500 rpm the 6C 1900 could achieve a top speed of 130 km/h; the improved frame consisted of boxed rails and crossmembers, instead of the 1750s C-shaped sec