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Automatic Cars

Automatic Cars

2010 Maserati Granturismo S Automatic

Maserati announced today that it will unveil the GranTurismo S Automatic at the 2009 Geneva Motor Show next week. The GranTurismo S Automatic will be powered by the same 4.7L V8 making a total of 440-hp with a maximum torque of 361 lb-ft.

The engines will be mated to a ZF 6-speed automatic gearbox. Other than that, the Maserati GranTurismo S Automatic features all the aggressive styling from its GranTurismo S sibling along with the 20-inch wheels. Inside the GranTurismo S Automatic features Bluetooth as standard with an optional iPod interface that completes the Maserati Multi Media System.

Welcome to AutomaticCar.net so what is so great about an Automatic Car?? Well an an autmatic car is so called because it has automatic transmission ("AT") this is an automobile transmission that can change gear ratios automatically this isas the vehicle moves, having an automatic car frees the driver from having to shift gear and in theory helps to make driving easier. Most automatic transmissions have a set selection of possible gear ranges. These tend to be drive, reverse, and park.

Interesting fact, did you know that most cars sold in the USA from the 1950s onwards have been equipped with an automatic transmission. Althought the truth is that these cars have not caught on in Europe as much, and in most of the Asian markets automatic transmissions cars have become popular since the 1990s onwards. Automatic transmissions are great because they provide lower fuel needs, and have the same power as a manual transmission. Automatic transmissions are also easier for drivers, especially beginners, as they do not need to worry about pumping the clutch and finding the correct gear. In some jurisdictions, drivers passing their driving test in an automatic-transmission vehicle will not be licensed to drive a manual-transmission Automatic Car, and this is also true of the UK driving License system. However, a driver who holds a manual license will be permitted to drive an automaticcar.

Automatic transmission

An automatic transmission (often informally shortened to auto, and abbreviated to AT) is a motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually. Similar but larger devices are also used for heavy-duty commercial and industrial vehicles and equipment.

Most automatic transmissions have a defined set of gear ranges, often with a parking pawl feature that locks the output shaft of the transmission. Continuously variable transmissions (CVTs), which are very different to conventional automatic transmissions, can change their 'ratios' over a wider 'stepless' range, rather than between a set of fixed gear ratios. CVTs have been used for decades in two-wheeled scooters; but have only seen use in a few automobile models. Recently, however, CVT technology has gained greater acceptance among manufacturers and customers, especially in Audi and Nissan automobiles, and gas-electric hybrid vehicles.

Some machines with limited speed ranges or fixed engine speeds, such as some forklift trucks and lawn mowers, only use a torque converter to provide a variable gearing of the engine to the wheels.

Comparison with manual transmission

Most cars sold in the North America since the 1950s have been available with an automatic transmissi on.[citation needed] Conversely, automatic transmission is less popular in Europe, with 80% of drivers opting for manual transmission.[1] In most Asian markets and in Australia, automatic transmissions have become very popular since the 1990s.[citation needed]

Vehicles equipped with automatic transmissions are, arguably, easier to drive. Consequently, in some jurisdictions, drivers who have passed their driving test in a vehicle with an automatic transmission will not be licensed to drive a manual transmission vehicle.[citation needed] Examples of driving license restrictions are Croatia, Dominican Republic, Israel, United Kingdom, some states in Australia, France, Portugal, Latvia, Lithuania, Ireland, Estonia, Belgium, Germany, Pakistan, the Netherlands, Sweden, Austria, Norway, Poland, Hungary, South Africa, Trinidad and Tobago, China, Hong Kong, Macau, South Korea, Singapore, United Arab Emirates, India, Finland, Switzerland and New Zealand (Restricted licence only

Hydraulic automatic transmissions

A hydraulic automatic transmission consists of the following parts:

Torque converter: A type of fluid coupling, hydraulically connecting the engine to the transmission. It takes the place of a mechanical clutch, allowing the transmission to stay 'in gear' and the engine to remain running whilst the vehicle is stationary, without stalling. A torque converter differs from a fluid coupling, in that it provides a variable amount of torque multiplication at low engine speeds, increasing "breakaway" acceleration. This is accomplished with a third member in the "coupling assembly" known as the stator, and by altering the shapes of the vanes inside the coupling in such a way as to curve the fluid's path into the stator. The stator captures the kinetic energy of the transmission fluid, in effect using the leftover force of it to enhance torque multiplication.
Planetary gearset: A compound epicyclic planetary gearset, whose bands and clutches are actuated by hydraulic servos controlled by the valve body, providing two or more gear ratios.
Clutches and bands: to effect gear changes, one of two types of clutches or bands are used to hold a particular member of the planetary gearset motionless, while allowing another member to rotate, thereby transmitting torque and producing gear reductions or overdrive ratios. These clutches are actuated by the valve body (see below), their sequence controlled by the transmission's internal programming. Principally, a type of device known as a sprag or roller clutch is used for routine upshifts/downshifts. Operating much as a ratchet, it transmits torque only in one direction, free-wheeling or "overrunning" in the other. The advantage of this type of clutch is that it eliminates the sensitivity of timing a simultaneous clutch release/apply on two planetaries, simply "taking up" the drivetrain load when actuated, and releasing automatically when the next gear's sprag clutch assumes the torque transfer. The bands come into play for manually selected gears, such as low range or reverse, and operate on the planetary drum's circumference. Bands are not applied when drive/overdrive range is selected, the torque being transmitted by the sprag clutches instead. Bands are used for braking; the GM Turbo-Hydramatics incorporated this.[citation needed]
Valve body: hydraulic control center that receives pressurized fluid from a main pump operated by the fluid coupling/torque converter. The pressure coming from this pump is regulated and used to run a network of spring-loaded valves, check balls and servo pistons. The valves use the pump pressure and the pressure from a centrifugal governor on the output side (as well as hydraulic signals from the range selector valves and the throttle valve or modulator) to control which ratio is selected on the gearset; as the vehicle and engine change speed, the difference between the pressures changes, causing different sets of valves to open and close. The hydraulic pressure controlled by these valves drives the various clutch and brake band actuators, thereby controlling the operation of the planetary gearset to select the optimum gear ratio for the current operating conditions. However, in many modern automatic transmissions, the valves are controlled by electro-mechanical servos which are controlled by the electronic engine control unit (ECU) or a separate transmission control unit (TCU). (See History and improvements below.)
Hydraulic & lubricating oil: called automatic transmission fluid (ATF), this component of the transmission provides lubrication, corrosion prevention, and a hydraulic medium to convey mechanical power (for the operation of the transmission). Primarily made from refined petroleum, and processed to provide properties that promote smooth power transmission and increase service life, the ATF is one of the few parts of the automatic transmission that needs routine service as the vehicle ages.
The multitude of parts, along with the complex design of the valve body, originally made hydraulic automatic transmissions much more complicated (and expensive) to build and repair than manual transmissions. In most cars (except US family, luxury, sport-utility vehicle, and minivan models) they have usually been extra-cost options for this reason. Mass manufacturing and decades of improvement have reduced this cost gap.