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Automatic Car Transmission Repairs

Automatic transmission, also called auto, self-shifting transmission, n-speed automatic (where n represents its number of forward gear ratios), or AT, is a type of motor vehicle transmission that automatically changes the gear ratio as the vehicle moves, meaning that the driver does not have to shift the gears manually. Like other transmission systems on vehicles, it allows an internal combustion engine, best suited to run at a relatively high rotational speed, to provide a range of speed and torque outputs necessary for vehicular travel. The number of forward gear ratios is often expressed for manual transmissions as well (e.g., 6-speed manual).


The most popular form found in automobiles is the hydraulic planetary automatic transmission. Similar but larger devices are also used for heavy-duty commercial and industrial vehicles and equipment. This system uses fluid coupling in place of friction clutch and accomplishes gear changes by hydraulically locking and unlocking a system of planetary gears. These systems have a defined set of gear ranges, often 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 conventional hydraulic automatic transmissions with torque converters, there are also other types of automated transmissions, such as belt-driven continuously variable transmissions (CVT), automated manual transmissions (AMT), dual-clutch transmissions (DCT), that free the driver from having to shift gears manually, by using the transmission's computer to change gear, if for example; the driver was redlining the engine. Despite superficial similarity to other transmissions, traditional automatic transmissions differ significantly in internal operation and driver's feel from automated manuals 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. An automated manual retains a clutch like a conventional manual transmission, but controls and depresses the clutch through hydraulic, pneumatic, or electrical means, and automates the clutch and shifting process. The ability to shift gears manually, often via paddle shifters, can also be found on certain automatic transmissions (manumatics such as Tiptronic), automated manuals (BMW SMG, Ferrari F1, VW Group DSG), and CVTs (such as Lineartronic).


Most Common Automatic Transmission faults and problems:

  • Grinding or shaking sensation in gear.

  • Car won't engage or respond when in gear.

  • Makes Noises: whining, humming or clunking, noisy in neutral.

  • Smells like its burning.

  • Gears Slipping.

  • Low or leaking fluid.

  • Check engine light is on.

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