Automatic transmission is one of the oldest forms of vehicle transmission used in motorized vehicles. Along with the manual transmission of course.
But not all automatic transmissions are created equal. They have their own variety depending on the type and needs of a vehicle.
So if you are unaware of what type of gear box your car has, then this post is for you. Read on and learn the different types of automatic transmissions.
History of Automatic Transmission
A little bit of history for you guys. The first ever automatic transmission was first invented in 1904 which is called the Sturtevant Horseless Carriage Gearbox.
However, the first mass-produced automatic transmission was built by General Motors, the Hydramatic 4-speed hydraulic automatic, which was introduced way back in 1939 (1).
It uses a fluid coupling instead of a torque converter, which is now widely used these days.
The first automatic transmission that uses hydraulic fluid was first developed by two Brazilian engineers, Jose Braz Araripe and Fernando Lehly Lemos.
And the first automatic transmission to use a torque converter was introduced in 1948 and was called the Buick Dynaflow. It was followed by Packard Ultramatic in 1949 and the Chevrolet Powerglide in the 50’s.
By the late 1960’s, most of the fluid-coupling 2-speed and 4-speed transmissions are obsolete in favor of the 3-speed units with torque converters.
And in the 80’s, automatic transmissions with four gear ratios became the popular choice among car manufacturers (2). Along with this new transmission tech, electronics has played a crucial role in controlling the transmission, which replaces the old mechanical system.
Most trannies are now using solenoids which are controlled by either the engine control unit or a standalone transmission control unit (TCU).
What is Automatic Transmission?
Automatic transmission or simply called as AT, is a multi-speed transmission used in modern automobiles. It doesn’t require the driver to change gears under normal driving conditions.
AT uses a torque converter, gearset and clutches (or bands) to shift gears automatically. Aside from these transmission components, AT includes an axle, and differential in one integrated assembly, thus technically becoming a transaxle.
Today’s AT allows the driver to control upshifts or downshifts by just utilizing buttons or paddle shifters located on the steering wheel or at the gear selector. These are called “tiptronic” or manual mode.
So let me give you some of the types of automatic transmission.
Automated Manual Transmission
As its name suggest, automated manual transmission or known as AMT, is a automatic transmission with a mechanical design and build comparable to a conventional manual transmission.
It uses a automatic actuation to control the clutch or the gear shift mechanism. In Layman’s term, AMT employs a mechanical clutch that is not driven by a clutch pedal but an automated clutch using electronic or hydraulic system.
Click here and learn how to drive an automatic transmission.
Continuously Variable Transmission
One of the widely used (and criticized) AT is called continuously variable transmission (also abbreviated as CVT).
Conventional AT provides a limited number of gear ratios in fixed steps. But CVT can seamlessly change using continuous range of variable gear ratios. This design allows the engine to operate at a constant RPM while the vehicle moves at different speeds.
CVTs are widely used in various automobiles, tractors, bicycles and many others. Car manufacturers had their own designs of CVTs but mostly uses two pulleys that are connected by a belt or chain.
Dual Clutch Transmission
Sometimes called as twin-clutch transmission, dual clutch transmission is another multi-speed automatic transmission that uses “two” separate clutches for odd and even gear sets. Hyundai Accent, which I own one uses a DCT.
DCT uses two clutches controlling the even and odd gear ratio. It also has two transmission shafts that controls the gear ratios that are divided the odd one being inside and the even and longer.
Dual clutch transmission provides comfort and efficiency as gears are shift smoothly which gives a zero jerk effect while shifting. DCT is also the fastest system among the AT line ups. This is the reason why race cars and luxury exotic cars use this type of tranny.
Summary
There you go! Now you know the types of automatic transmission. It’s time to investigate and see what type of AT your car have.
But what if you have trouble with your transmission? Lets say fluid leak? What should you do and how to diagnose transmission leak? The video below will educate you more!
The video is in Tagalog language but has English subtitle. Enjoy!
References:
40 Automatic Transmission History
https://www.autorepairsanantonio.com/40-automatic-transmission-history
Advanced Transmission Technologies
https://www.fueleconomy.gov/feg/tech_transmission.shtml
