urgent need of ppt on automated gear shifting mechanism

I need project on hydraulic system quick return mechanism

An automatic transmission, also called auto, auto-shift transmission, automatic n-speed (where n is its number of forward ratios), or AT, is a type of vehicle transmission that can automatically change the gear ratios As the vehicle moves, freeing the driver from having to manually change the gears. Like other vehicle transmission systems, it allows an internal combustion engine, more suited to operate at a relatively high rotational speed, to provide a range of speeds and torque outputs required for the vehicular journey. The number of forward ratios is often also expressed for manual transmissions (eg, 6-speed manual).The most popular form found in automobiles is the automatic hydraulic transmission. Similar but larger devices are also used for vehicles and industrial and heavy equipment. This system uses a fluid coupling instead of a friction clutch and makes gear changes by hydraulically blocking and unlocking a planetary gear system. These systems have a defined set of gear ranges, often with a parking ratchet that locks the output shaft of the transmission to prevent the vehicle from rolling 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 variable gear from motor to wheels.

In addition to traditional hydraulic automatic transmissions, there are also other types of automated transmissions, such as a continuously variable transmission (CVT) and semiautomatic transmissions, which relieve the driver from having to manually shift gears, using the transmission computer to change If, for example, the driver was redlining the engine. Despite the superficial similarity to other transmissions, traditional automatic transmissions differ significantly in both internal performance and driver feel from semi-automatitics and CVTs. Unlike 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 as a manual transmission, but controls the clutch through electrohydraulic means. The possibility of changing gears manually, often through paddle shifting, can also be found in certain automatic transmissions (manumentics such as Tiptronic), semiautomatic (BMW SMG, VW Group DSG) and CVTs (like Lineartronic).

The obvious advantage of an automatic transmission to the driver is the lack of a clutch pedal and a manual shift pattern in normal driving. This allows the driver to operate the car with only two members (possibly using assistive devices to position the controls within reach of the usable members), allowing amputees and other persons with disabilities to drive. The lack of manual shift also reduces the attention and the required workload inside the cab, such as controlling the tachometer and pulling a hand off the wheel to move the shift lever, allowing the driver to keep both hands on the wheel at Every moment and focus more on the road. Controlling the car at low speeds is often easier with an automatic than a manual, because of a side effect of the clutch-less fluid coupling design called "creep" that causes the car to want to move while in a driving gear, Even at idle. The main disadvantage of the most popular hydraulic designs is the reduction of the mechanical efficiency of the power transfer between the engine and the power train, due to the hydraulic coupling that connects the engine to the gearbox. This can result in lower power / torque of the automated systems compared to manuals with the same engine specifications, as well as lower fuel efficiency in urban driving, as the engine must be kept idle against the resistance of the engine coupling. fluid. Advancements in the design of transmission and coupling have considerably reduced this gap, but clutch-based transmissions (manual or semi-automatic) are still preferred in the sports equipment levels of several production cars, as well as in many motor racing leagues.