Inside Of Transmission: Everything You Need To Know

An automatic transmission is a complex system that moves power from the engine to the wheels without the driver having to change gears by hand. It is a necessary part of modern cars and plays a crucial role in making sure that a car runs smoothly and efficiently.

In this article, we will provide an overview of the automatic transmission diagram, the three parts of an automatic transmission, the various parts of an automatic transmission, how an automatic transmission works simplified, and common problems associated with automatic transmissions.

An Automatic Transmission’s Three Parts

The torque converter, the planetary gear set, and the hydraulic control system are the three main parts of an automatic transmission. Each of these parts is very important for the transmission to work well.

1.     Torque Converter

The torque converter is between the engine and the transmission. It sends the power from the engine to the transmission. The impeller, the turbine, and the stator are the three parts that make it up.

Automatic transmission with torque converter shown.

The impeller is attached to the crankshaft of the engine and spins when the engine runs. The spinning impeller makes a flow of transmission fluid, which turns the turbine, which is connected to the transmission. The stator changes the flow of fluid so that the engine can make more torque and power.

In an automatic transmission, the torque converter acts like a clutch, letting the engine keep running even when the car is stopped. The torque converter also makes the power transfer from the engine to the transmission smooth and gradual. This lets the car speed up smoothly.

2.     The Planetary Gear Set

The heart of an automatic transmission is the planetary gear set. It is made up of several parts, including the sun gear, the planet gear, the ring gear, and the carrier. The planetary gear set works by putting together different gear ratios to give the vehicle the right speed and torque.

The sun gear is connected to the input shaft. The torque converter turns the input shaft. The carrier, which is connected to the output shaft, holds the planet gears. The ring gear is fixed, and the planet gears mesh with it to make different gear ratios.

The planetary gear set gives the vehicle the different gear ratios it needs to speed up, keep its speed, or slow down as needed. The transmission can send the right amount of torque and power to the wheels by combining different gear ratios.

3.     Hydraulic Control System

The planetary gear set is controlled by the hydraulic control system, which also makes sure the transmission works smoothly. It is made up of a series of valves, solenoids, and other parts that control the flow of transmission fluid through the transmission.

Hand on automatic gear shift.

The throttle position sensor, the vehicle speed sensor, and the transmission temperature sensor are some of the sensors in the car that send signals to the hydraulic control system. The hydraulic control system changes the flow of transmission fluid based on these signals to control the gear ratios and make sure the transmission works smoothly.

What Are The Parts Of Automatic Transmission?

An automatic transmission is made up of many parts that all work together to keep the transmission running smoothly and efficiently. Among the most important parts of an automatic transmission are the following:

1.     Transmission Fluid

Transmission fluid is a type of lubricant that is needed for an automatic transmission to work right. It lubricates the different parts of the transmission that move, keeps the transmission cool, and helps the engine send power to the transmission. It also helps control how the transmission works by acting as a hydraulic fluid.

2.     Transmission Pump

Transmission fluid moves through the transmission with the help of the transmission pump. It is usually inside the torque converter, and the engine powers it. The transmission pump makes sure that the hydraulic control system and the different parts of the transmission always have enough transmission fluid.

3.     Transmission Filter

It’s up to the transmission filter to keep going to filter the transmission fluid and get rid of any dirt or debris that might be in it. If the transmission filter is dirty or clogged, the transmission may not work well or even break. This is why it is important to replace the transmission filter regularly.

Close up photo of a transmission filter.

4.     Valve Body

The body of the valve is an important part of the hydraulic control system. It has a series of valves and passages that control the flow of transmission fluid through the transmission. Different sensors in the car send signals to the valve body.

Based on these signals, the valve body changes the flow of fluid to control the gear ratios and make sure the transmission works smoothly.

5.     Bands and Clamps

The different gears in the transmission engage and disengage with the help of clutches and bands. They are made of a series of friction plates that are held together by springs or hydraulic pressure. When a clutch or band is engaged, it locks two parts of the transmission together. This lets the engine send power to the wheels.

6.     Solenoids

Solenoids are electronic parts that control the flow of transmission fluid through the transmission. They are run by the hydraulic control system and are in charge of turning on and off the clutches and bands in the transmission. Solenoids can break down over time, which can make the transmission work badly or even stop working.

How A Transmission With An Automatic Gearbox Works

The power from the engine is sent to the wheels through an automatic transmission by a combination of hydraulic pressure and mechanical parts. Here are the most important steps for making an automatic transmission work:

  • The torque converter gets the power from the engine.
  • The torque converter sends power to the transmission pump, which pumps transmission fluid through the hydraulic control system.
  • The hydraulic control system gets information from the vehicle’s sensors and changes the flow of transmission fluid to control the gear ratios and make sure the transmission works smoothly.
  • The planetary gear set puts together different gear ratios to give the vehicle the right speed and torque.
  • Different parts of the transmission are held together by clutches and bands that lock and unlock. This lets power go from the engine to the wheels.
  • Solenoids control the flow of transmission fluid through the transmission and move the clutches and bands into and out of place.
  • The transmission fluid keeps the transmission cool and helps move power from the engine to the transmission. It also lubricates the parts that move in the transmission.

Problems That Often Happen With Automatic Transmissions

Even though automatic transmissions are usually reliable, they can develop some common problems over time. The following are some of the most common problems with automatic transmissions:

1.     Transmission Fluid Leaks

Automatic transmissions often have leaks in the transmission fluid. Leaks can come from the transmission pan, the transmission cooler lines, the input shaft seal, or the output shaft seal. A transmission fluid leak can make the transmission work poorly or even stop working, so it’s important to fix any leaks as soon as possible.

2.     Solenoid Failure

Solenoids are electronic parts that control the flow of transmission fluid through the transmission. Over time, the solenoids can break, which can make the transmission shift poorly or even stop working. Most of the time, you can just replace the solenoids instead of the whole transmission.

3.     Overheating

Automatic transmissions can get too hot if they are asked to do too much, like tow a heavy load or drive in traffic with lots of stops and starts. If the car gets too hot, the transmission fluid can break down. This can cause the transmission to work poorly or even fail.

A woman in trouble with broken, overheat car with smoke from damaged engine.

4.     Bands or Clutches Worn

The different gears in the transmission engage and disengage with the help of clutches and bands. As time goes on, the friction material on the clutch and band plates can wear down, which can make the transmission slip or shift poorly. To get the transmission to work right again, worn clutches and bands will need to be replaced.

5.     Filter for Transmission is Clogged

The transmission filter’s job is to filter the transmission fluid and get rid of any dirt or debris that might be in it. If the transmission filter is dirty or clogged, the transmission may not work well or even break. This is why it is important to replace the transmission filter regularly.

6.     Torque Converter Problems

The torque converter takes power from the engine and sends it to the transmission. When there are problems with the torque converter, the transmission can slip or not engage properly, which can make the transmission work poorly or even cause it to break.

Most problems with the torque converter can be fixed without having to replace the whole transmission.

Conclusion

In the end, an automatic transmission is a complicated and important part of a car’s drivetrain. It is made up of a number of mechanical and hydraulic parts that work together to send power from the engine to the wheels.

Understanding how the different parts of an automatic transmission work together can help people take better care of their cars and figure out what’s wrong with them if they break down.

Changing the transmission fluid and filter as part of regular maintenance can help make sure that an automatic transmission works smoothly and reliably for years to come.

Avatar photo
About Brock Rangel

Hi, I am Brock, and I am the lead editor/photographer for TheCarColony. I have been a mechanic for over 14 years now, and I am here to spread my car knowledge across the web!

Leave a Comment