Any automatic car isn't a mere manual car without a clutch pedal. The systems and mechanisms which are responsible for the automated shifting of gears in the transmission operate differently when compared to a manual transmission. Let us learn in detail about the different types of automatic gearbox in India and how to take care of them.
A torque converter-based automatic transmission is the most reliable and serviceable of the lot. A torque converter is nothing but a hydraulic fluid filled turbine drum assembly which, as its name suggests, converts and multiplies torque generated by the engine. It also serves the purpose of a clutch found in the manual transmission. i.e., it isolates the connection between the engine flywheel and the drivetrain during braking. Since a torque converter is the oldest form of automatic gearbox, it is the simplest in construction and thus, easy to maintain. It must be noted that torque converters are prone to higher torque loss as compared to other automatic gearboxes. This demands that the gearbox must be driven carefully uphill. Most torque converters are provided with manual gear override just for the purpose of driving uphill. A torque converter gearbox does not require any different driving style to maintain the life of the gearbox apart from the changes in driving habits when switching from manual to automatic.
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Unlike other automatic transmission systems which have limited gear ratios through which the system shifts for optimum speed and torque, the CVT unit comes with transmission pulleys and a belt for power transmission. This system provides the user with unlimited gear ratios while driving and makes sure that optimum torque is available at all times. It must be noted that CVTs fail at high torque inputs and hence cannot be seen in bigger engine vehicles. Since a CVT system does not have actual gears like other transmissions, the gearbox oil for CVTs is different than the others. While the purpose of other transmission fluids is to stay on the surface of gears to keep it lubricated, the transmission fluid in a CVT collects metal debris on the pulley surface to avoid slippage of the belt. Since CVTs have no actual gears meshing, a car with CVT transmission lacks towing capabilities and hence must not be used for pulling heavy loads.
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As its name suggests, a dual clutch transmission comprises of two clutches with alternate gear trains attached to each clutch, thus, while one clutch takes care of the engagement of odd numbered gear ratios, viz. 1st, 3rd, 5th gears, the other clutch engages even numbered gear ratios. Though the presence of two clutches does make the DCT a fastest shifting gearbox even when compared to the manual transmission, it also adds to the complexity of the gearbox. This complexity of mechanism results in higher cost of manufacturing, cost of repair and also high failure rate. This requires users to modify their driving style a little bit as compared to the above-mentioned transmissions to care for their DCTs. A DCT operates by switching between the two clutches which are engaged to their respective gear ratios. Thus, when a car with DCT is standing still in traffic for over a minute, it is advisable to put your car in neutral to avoid clutch wear and transmission maintenance. Care must also be taken that you do not shift the car to parking gear when halting for short intervals since the constant switching between park and drive will lead to increased clutch wear.
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An AMT is a result of technological advancement in the conventional manual gearbox. The work of a clutch pedal and gear shifter is done by electro-hydraulic components controlled by a dedicated controller. This shows that the AMT has some characteristics like manual transmission in combination with certain limitations from the hydraulics and electronics. Unlike all of the automatic transmissions mentioned above, the AMT does not have a dedicated parking gear on its shifter. Someone switching to AMT from any other automatic transmission need to make sure they have engaged parking brake after shifting the car into neutral when parking the vehicle. An AMT unit does have considerable torque loss and hence needs to downshift its gears and maintain the engine speed in powerband when climbing uphill. Likewise, one must also take care to not shift their car into neutral when going downhill since it renders engine braking almost useless.
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