Parts of a Car Automatic Transmission
Introduction
An automatic transmission is a type of transmission that allows the driver to shift gears without having to use a clutch pedal. This type of transmission is common in many modern vehicles, and it can be a great convenience for drivers. However, it is important to understand the parts of an automatic transmission in order to maintain and repair it properly.
Major Components
The major components of an automatic transmission include:
- Torque converter
- Planetary gearset
- Hydraulic control unit
- Valve body
Torque Converter
The torque converter is a fluid coupling that connects the engine to the transmission. It allows the engine to idle without stalling, and it also provides a smooth transfer of power from the engine to the transmission.
Planetary Gearset
The planetary gearset is a set of gears that provides the different gear ratios in an automatic transmission. The gearset consists of a sun gear, a planet carrier, and a ring gear. The sun gear is connected to the torque converter, and the planet carrier is connected to the output shaft. The ring gear is fixed to the transmission case.
Hydraulic Control Unit
The hydraulic control unit is a set of valves and solenoids that control the flow of fluid in the transmission. The hydraulic control unit receives signals from the transmission control module (TCM), and it uses these signals to shift gears.
Valve Body
The valve body is a set of passages and valves that direct the flow of fluid in the transmission. The valve body is controlled by the hydraulic control unit, and it uses the fluid pressure to shift gears.
Other Components
In addition to the major components listed above, there are a number of other components that are found in an automatic transmission. These components include:
- Accumulator
- Governor
- Shift solenoids
- Transmission fluid
Accumulator
The accumulator is a device that stores hydraulic pressure. The accumulator helps to smooth out the shifts between gears.
Governor
The governor is a device that measures the output shaft speed. The governor sends a signal to the hydraulic control unit, which uses this signal to shift gears.
Shift Solenoids
Shift solenoids are electrical solenoids that control the flow of fluid in the valve body. The shift solenoids are controlled by the hydraulic control unit, and they use the fluid pressure to shift gears.
Transmission Fluid
Transmission fluid is a special type of oil that lubricates and cools the components in the transmission. Transmission fluid also helps to transfer power from the engine to the transmission.
Conclusion
The automatic transmission is a complex piece of machinery, but it is an essential component of many modern vehicles. By understanding the parts of an automatic transmission, you can better maintain and repair this important part of your vehicle.
