Automatic Transmissions: How many are on the market?

As you may already know there are two main categories of transmissions on a car: Manual and Automatic Transmissions. Most of us are used with manual transmission or manual gearbox, the one where you must change gears every time you accelerate and brake, using the clutch pedal.

The manual gearbox has some advantages. First, it is cheaper to build and to maintain. Second, it gives you better control over the car, since you can control the torque using the clutch and you choose when to shift gears, either up or down.

For more than 10 years all I have driven had a manual transmission. But I want my next car to have an automatic transmission. So, how many types of the automatic transmission are on the market and which one is the best? Well, it depends on what car do you have. If you have an SUV, then the most likely automatic transmission is the best deal for you, maybe.

First, some history

An automatic gearbox or automatic transmission is a type of gearbox that can shift gears (change gear ratio) up and down as the car accelerates or decelerates. This way, the driver can focus on driving, or other things, like pedestrians, other cars, etc.

For years, automatic transmissions were not that perfect and they were quite expensive to buy or to repair. And they had constant problems, so it is natural that most people prefer the old manual gearbox instead.
In time, automatic transmissions got better and better and now are, in some way, even better than their manual sisters.

The biggest problem, nowadays, is the multitude of names and types of an automatic transmission, which confuses most buyers. Let’s see how many types are and which one is the best.

Automated Manual Transmission

This is the most simple and basic automatic transmission you can find. You will find it with different names from Robotic Transmission, SAT (Semi-automatic transmission), EAT< ETG, EGC, ASG, TipTronic, SMG and so on.

It is a manual gearbox with some sensors, an electronic control unit and a hydraulic system that will change gears automatically. The transmission can be used either fully automatically or in a semi-automatic way: sequentially.

Fuel efficiency is quite impressive: is almost identical to that of a manual gearbox. They are quite popular because they are very cheap, as an extra-option, and to repair.

Hydraulic automatic transmissions

 

You can find it on different names like 9G-Tronic, ZF 9-Speed, Geartronic, ZF 9HP, ZF 8HP or ZF 8 Speed, and so on.

This type of transmission has a lot of history behind it. If you ever had or you have driven an automatic transmission from the 80s or the 90s, then most likely, you have used a Hydraulic automatic transmission. It uses a thick hydraulic fluid, instead of a friction clutch, to transfer the power from the engine to the drive.

A set of planetary gears offer various gear ratios by altering the rotation speed of the output shaft depending on which planetary gear is locked. Hydraulic Controls the planetary gears by using some special transmission fluid. This way, the automatic transmission can modify the gear ratios and the speed of the output.
The biggest problem with this

type of transmission is when you move the car, at initial acceleration. Because the automatic transmission needs some time to build up fluid pressure, the car has a certain lag when accelerating the first time. This lag drives a lot of people away from automatic transmissions. Also, Torque Converters increase a bit of fuel consumption in a car.

A good thing about this Hydraulic automatic transmission is their reliability. Since the entire transmissions are based on the hydraulic fluid they are very reliable and the change gears very smoothly.

CVT or Continuously variable transmissions

A CVT is a type of automatic transmission than has only one gear (compared with 5,6, or even 9 on a Torque Converter). You may find it on different names on the market like twist-and-go, step-less transmission, single-speed transmission or pulley transmission.

This makes it very efficient in changing the gear ratio. The entire transmission is based on two wheels, or cones and a belt that connects those two. By varying the diameter of the pair, you can change the gear ratio. This type of automatic transmission is very popular in agriculture (tractors, combine harvester, etc) and snowmobiles, motor scooters, golf carts and so on.

On the good side: They are very simple to build and cheap to repair. On the downside: they don’t last a lot, compared with a manual transmission, but are very light and thus ideal for small vehicles.

Dual-Clutch automatic Transmissions or DCTs

This is the latest and most modern Automatic Transmission available on the market. You will find it on different names like DSG (Direct-Shift Gearbox) at Volkswagen, Powershift at Ford, DCT, PDK, Double-clutch, twin-clutch, R-Tronic, DualTronic, SpeedShift, and so on.

In essence, it combines two manual transmissions each one with its clutch. One transmission is responsible for odd gears and the other one for even gears and reverse. They share the same house and work as a single transmission.

One big advantage of this type of automatic transmission is its speed in changing gears, around 8ms. It can change gears faster than a professional racing driver can, which uses a racing manual gearbox. Another advantage is fuel consumption, identical with manual transmission and even better in some situations.

DCTs can have the two clutches either wet (bathed in oil) which helps to cool them, either dry. The Dry clutches are used in small cars, that develops torque up to 250 Nm while wet clutches are used in larger or sports cars.

Final Words

Over the last century, Automatic Transmissions have evolved a lot. Now they are better, faster and provide better fuel consumption compared with the manual siblings.

You should take into consideration, if you still have a manual transmission, to shift to automatic when you will change your car. We recommend automatic transmission especially for large cars (SUVs, Trucks, etc) and if you drive a lot in big cities. For large cars, we also recommend good tires (summer, winter, depending on the weather conditions. Check out our Top 5 SUV Winter Tires.