What does AT mean?

[Earl]

AT stands for torque converter automatic transmission. Other types of automatic transmissions include AMT, DCT, and CVT. The AT transmission is the most mature and widely used transmission technology. DCT, also known as dual-clutch transmission, has a structure similar to manual transmissions but features two sets of clutches. One clutch controls odd-numbered gears, while the other controls even-numbered gears. DCTs offer fast shifting speeds, high transmission efficiency, and are well-suited for use with small-displacement turbocharged engines. AMT is the earliest type of automatic transmission. Its structure is identical to a manual transmission, but it includes a control mechanism that operates the clutch and gear shifts. CVT transmissions are commonly used in some domestic and Japanese cars. They are compact, lightweight, and cost-effective. Most vehicles equipped with CVTs are highly fuel-efficient. CVTs provide smooth shifting without any noticeable jerking. AT transmissions exhibit minimal shift shock, while DCTs can produce noticeable jerking during low-speed shifts. AMT transmissions have significant shift shock and have largely been phased out. The development and manufacturing costs of AT transmissions are generally high, and they are often used in high-end vehicles. A manual-automatic transmission combines manual and automatic shifting modes. This type of transmission integrates the advantages of both automatic and manual transmissions, minimizing power loss in the shifting system. While manual mode allows drivers to freely adjust gears and RPMs, unlike pure manual transmissions, manual-automatic transmissions feature an automated clutch system. In manual mode, drivers only need to shift gears up or down based on speed. If the speed doesn't match the selected gear, the transmission will automatically downshift; if the speed exceeds the gear's range, manual upshifting is required. Working Principle: Structurally, a manual-automatic transmission consists of a standard gearbox (similar to a manual transmission), an electronically controlled clutch, an automatic shift mechanism, and an electronic control unit. The electronically controlled clutch automatically engages, disengages, or partially engages the clutch as needed, controlled by the transmission ECU via a stepper motor. The automatic shift mechanism selects the appropriate gear using two stepper motors, also controlled by the ECU. The gear lever resembles that of an automatic transmission, with no clutch pedal. Essentially, the system simulates manual shifting through automation. During normal driving, it operates like a hydraulic automatic transmission, but the clutch disengages when the vehicle is stationary, requiring the brake to be pressed on slopes to prevent rolling. In manual mode, the driving experience resembles that of a manual transmission, with direct power delivery and no need to operate the clutch. Gear changes can also be skipped rather than sequential. Product Types: Electronic and hydraulic controls are added to the base automatic transmission. Even in manual mode, the system remains under automatic control—automatically upshifting if forgotten, preventing downshifts at high speeds, starting in 1st or 2nd gear, and switching to "adverse weather mode" to prevent wheel slip. Combines a traditional H-pattern manual transmission with an automated clutch system, retaining the manual shift mechanism while automating clutch operation. Integrates an automated clutch with electronic-hydraulic sequential shifting, based on a manual transmission.