automatic gear transmission


Power transmission is simply known as transmit of power from one shaft to another to maintain required speed and torque.  Since years combination of gears and gear trains are used to transmit power in automobiles. This power transmission device is known as gearbox. Modern automobiles specially two wheelers and four wheels are very popular in modern automobile sector.

Standard gear ratio of each gear differentiates the rotation of wheels. The drive force that causes the rotation of car wheels inside the engine well known as torque. The torque is being transmitted to the wheel through the shaft of the engine. Modern car Transmission is available in two different type’s i.e.  Automatic or manual. In a manual power transmission, the driver has to shift the gears and thus responsible for required speed and torque, while in a car with an automatic transmission, the car automatically changes the speed and torque as per requirement.


manual gear transmission

Stick shifts are available in conventional cars since years. The drivers use the stick shift manually and shift the gears. Thus the driver controls the speed of the car. In this conventional car transmission system the stick is connected to the transmission by a linkage. To control the speed and torque in different loading condition of the engine the clutch pedal is used to engage and disengage gears. Pressing the clutch pedal results to disengage the contact between two different gears and thus stops power transmission in the car and vice versa. So to obtain required speed, the driver press the clutch pedal and with the help of stick shifts engage gears.

Then he releases the clutch pedal. This requires proper practice for a beginner and lots of concentration is required. The mismatch between application of clutch and lever shifting some times stops the vehicle engine. Every shift of lever provides different speed and torque. Starting from invention of car two speeds to seven speed gear box were seen in automobile engine.  However, mentioning the traffic scenario in the world the manual gearbox can frustrate and irritate you. It is also noted that once you can drive a car with a manual gearbox makes it easier to drive a car with any gearbox.


automatic gear transmission

The driver plays the most important role in maintaining the speed of a car in manual transmission system. But in an automatic transmission system the driver need not to worry about that.  In automatics car transmission system the fluid pressure automatically controls the gear changes on its own. The automatic transmission consists of set of planetary gears. The fluid also works as coolants to cools the moving parts of the transmission. A torque converter plays an important role to accelerate or retard of the car. Fluid is used to lock and unlock planetary gears to change between gear rations. Therefore an automatic transmission looks pretty cool and you just put it in drive. An automatic transmission has sensors to recognize when it should change gears and this is achieved by using internal oil pressure. There are many automatic power transmission technologies available in modern cars. They are classified as below: 

Continuous Variable Transmission (CVT)

cvt gear transmission

In manual or conventional automatic transmissions it is noticed that there is interruption in pulling the car as speed changes. But in Continuous Variable Transmission (CVT) it does not happen while pulling the car. The acceleration is very smooth as compared to others. In the CVT there exists of two sets of conic discs over which the belt is rotated. In this technology the distance between the two disks is changing continuously and thus the radius of the belt will be changing. This allows a variable transmission while changing the speed. This is suitable for high load and comfort.

Examples of CVT

  • M-CVT by Nissan
  • LHD by Lexus
  • VTi by GM
  • Autotronic byMB
  • SECVT by Suzuki
  • Lineartronic by Subaru

Dual Clutch Transmission (DCT)

dct gear transmission

The dual clutch transmission (DCT) technology is introduced in late nineties. The name given by AUDI is Dual Shift Gearbox. The gear transmission system is fitted with two different axles. The design is flexible for luxury cars. The purpose of the axles is that one axle is fitted with even gears and the other axle is fitted with the odd gears. There is a smooth and continuous acceleration generated without any jerk. This technology is applied in superfast cars. The advantage is that fuel consumption is low.

Examples of DCT

  • DCT by BMW
  • DSG by Audi
  • S-Tronic by Audi
  • PowerShift by Volvo
  • PDK by Porsche
  • SpeedShift by MB
  • TC-SST by Mitsubishi

Automated Manual Transmission (AMT)

amt gear

The construction of Automated Manual Transmission (AMT) is similar to manual transmission systems. The difference is the shifting of gear is controlled automatically. This system does not have any clutch pedal and gear changing lever. In AMT Additional actuators are there which is mounted on the gearbox. The transmission steps are controlled electronically. Many AMT cars are provided both modes of transmission i.e. automatic mode or a manual mode. The main advantages of AMT system are that less fuel consumption and low production cost

Examples of AMT

  • Hondamatic by Honda
  • SMG by BMW
  • Allshift by Mitsubishi
  • NAVi5 by Isuzu
  • Daimatic by Daihatsu
  • Quickshift by Renault
  • Easytronic by Opel
  • MMT by Toyota

Conventional Automated Transmission (AT)

cat gear

Conventional automated Transmission is similar to conventional gear system. The oil pressure controls the transmission in a conventional automated Transmission (AT) and thus high speed is maintained. Similarly when the car slows down, the gearbox comes back to a lower gear. Number of sensors is being used in modern AT system which controls the oil pressure. Therefore switching time is faster and flexible. As compared to AMT this transmission system has faster transmission response and comfortable in switching gears.

Examples of AT

  • Powertech by Hyundai
  • Tiptronic by Audi
  • G-Tronic by MB
  • Matic by Nissan
  • Cruise-O-Matic by Ford
  • Steptronic by BMW


Lower purchase price.Higher purchase price than manual.
Less expensive to service.Higher repair costs for service.
Many drivers like the feeling of being in controlEasy to use and less stress.
Requires practice to learn how to use.Driver must coordinate clutch, gas and shifting.Good for beginners.
Superior acceleration – favored by racecar and performance drivers.Superior acceleration favored by all ages of people.
Lower resale value.Higher resale value.
Can be difficult to drive in stop and go traffic.Great in stop and go traffic
Earlier less fuel efficiency not in competitionHistorically less fuel efficient than manual – but the gap is closing

Which transmission should we prefer?

Above all we have learnt two basic transmission system i.e. manual and automatic transmission systems. Both have pros and cons as per various conditions. The big question is which type of transmission system we will go for. The selection totally depends on your budget, traffic condition, distance travel and experienced or new in driving. If you drive a lot in the city then an automatic may be convenient to maneuver through stop and go traffic than a manual transmission system. If you are thinking about performance and have driving experience then you might want to consider a manual transmission.

automatic gear transmission
  • Very informative. I learned so much about cars

  • chelsie says:

    This was very well worded and thorough! Loved the information provided.

  • Anju Rai says:

    Great information.. Thank you

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