The transmission is, of course, a critical part of a vehicle’s powertrain, since it transfers the engine’s power to the driven wheels. Automotive engineers aim to minimise power losses in the transmission, while maximising efficiency. An efficient transmission system can help improve fuel economy in a big way, while ensuring that most of the power produced by the engine actually gets to the wheels, thereby maximising acceleration and top speed.
The transmission traditionally consists of gears that move and slot into position when they are engaged, to deliver torque to the drive shaft of the vehicle. Conventional transmissions make use of a manually operated clutch, which temporarily disengages gears from the engine, and then re-engages the next chosen cog as smoothly and seamlessly as possible.
In India, the manual transmission has been the norm for decades, since it provides a combination of lower costs and better fuel economy compared to the regular, torque-converter automatic. Globally, General Motors (GM) was one of the first companies to introduce an automatic transmission, which did not require the use of a manual clutch. GM introduced its ‘HydraMatic’ transmission in the 1940 Oldsmobile, which it then also offered on various Cadillacs.The HydraMatic system combined the hydraulic operation of a planetary gearbox with a fluid coupling instead of a friction clutch, which eliminated the need for de-clutching. The transmission had four forward speeds and a reverse, and also incorporated a parking pawl which was engaged when the gearshift selector was placed in reverse, with the engine off.
With decades of evolution, today we have many different kinds of automatic transmissions, including the traditional automatic, the automated manual transmission (AMT), dual clutch automatic transmission (DCT) and the continuously variable transmission (CVT). These automatics are not limited to passenger vehicles alone, but are also seen in various types of commercial vehicles and off-highway vehicles.
AT REMAINS RELEVANT
この記事は Auto Tech Review の December 2016 版に掲載されています。
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この記事は Auto Tech Review の December 2016 版に掲載されています。
7 日間の Magzter GOLD 無料トライアルを開始して、何千もの厳選されたプレミアム ストーリー、9,000 以上の雑誌や新聞にアクセスしてください。
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