Is an AT Transmission Automatic or Manual?

[McKeegan]

An AT transmission is an automatic transmission with a manual mode, belonging to the category of automatic transmissions. 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 a dual-clutch transmission, has a structure similar to a manual transmission but features two sets of clutches. These two clutches control odd and even gears respectively. Dual-clutch transmissions offer fast gear shifts, high transmission efficiency, and are well-suited for pairing with small-displacement turbocharged engines. AMT is the earliest type of automatic transmission. Its structure is identical to a manual transmission, except it includes a control mechanism that manages the clutch and gear shifts. CVT transmissions are commonly used in some domestic and Japanese vehicles. These transmissions are compact, lightweight, and cost-effective. Most cars equipped with CVT transmissions are highly fuel-efficient. CVT transmissions provide smooth operation without any noticeable gear shift jerks. AT transmissions exhibit minimal shift jerks, while DCT transmissions can produce noticeable jerks during low-speed shifts. AMT transmissions, which have significant shift jerks, 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 semi-automatic transmission combines the features of manual and automatic transmissions. This technology was developed to enhance the fuel efficiency and drivability of automatic transmissions, allowing drivers to manually control gear shifts instead of relying solely on computer decisions, thereby improving driving dynamics and enriching the driving experience. A semi-automatic transmission integrates manual and automatic shifting modes. It combines the advantages of both automatic and manual transmissions, minimizing power loss in the transmission system. Unlike pure manual transmissions, semi-automatic transmissions feature a clutch mechanism that operates automatically, requiring no manual clutch pedal operation. When in manual mode, drivers simply shift gears up or down based on speed changes. If the speed doesn't match the selected gear, the transmission will automatically downshift; if the speed exceeds the gear's range, the driver must manually upshift. Working Principle: Structurally, a semi-automatic transmission consists of a conventional gearbox (similar to a manual transmission), an electronically controlled clutch, an automatic gear shift mechanism, and an electronic control unit. The electronically controlled clutch automatically engages or disengages the clutch as needed, controlled by the transmission ECU via a stepper motor that moves the clutch fork. The automatic gear shift mechanism selects the appropriate gear, typically using two stepper motors controlled by the transmission ECU. The gear lever setup resembles that of a conventional automatic transmission, with no clutch pedal. The transmission operates by simulating manual gear shifts through automated controls. Under normal driving conditions, it functions similarly to a hydraulic automatic transmission, but when stationary, the clutch remains disengaged, requiring the driver to use the brake to prevent rolling on slopes. In manual mode, the driving experience resembles that of a manual transmission, delivering direct power response without the need for clutch operation, and allowing for skip-shifting (jumping gears). Product Types: This type adds electronic and hydraulic controls to an automatic transmission. Even in manual mode, the automatic system remains active, automatically upshifting if the driver forgets or preventing downshifts at high speeds. It starts in 1st or 2nd gear and can switch to a "bad weather mode" to prevent wheel slip. This system combines a conventional "H"-pattern manual transmission with an automated clutch, automating only the clutch while retaining the traditional manual gear shift mechanism. This type integrates an automated clutch with an electro-hydraulic sequential gear shift system, based on a manual transmission.