An automatic transmission is one of the most complex and essential components of a vehicle. It is responsible for automatically shifting gears so that the appropriate amount of power is delivered to the vehicle’s wheels. As a result, the car is able to travel at various speeds. In order to accomplish its important purpose, the automatic transmission system relies on a wide variety of different parts to function seamlessly together. Having a knowledge of the various parts of an automatic transmission will help you better understand how the system works so that you can better maintain it and prevent potential issues. To learn about the basic components of an automatic transmission, continue reading.
Planetary Gearset
The planetary gearset, also known as the epicycloidal gearset, is undeniably one of the most important components of an automatic transmission. As the focal point of the system, all other components of the automatic transmission are essentially designed to facilitate its operation. The purpose of the planetary gearset is to create all of the gear ratios that the transmission produces and allow the system to change gears smoothly without requiring the driver to physically move the gear shift.
In order to facilitate such important operations, the planetary gearset consists of three primary components: the sun gear, the planet gear, and the ring gear. These gears are connected by a moveable arm and mounted so that the center of one of the gears revolves around the center of the other. The gear ratio of the system is determined by which of the three gears serves as the input, which serves as the output, and which is held stationary. To produce different gear ratios, the automatic transmission locks different gears accordingly.
Torque Converter
Another primary component of an automatic transmission system is the torque converter. Instead of a clutch that is typically included in manual transmission systems, automatic models contain a torque converter which serves a similar purpose. The torque converter is responsible for delivering power from the engine of a vehicle to its transmission system. When a vehicle comes to a stop and the engine idles, the torque converter absorbs the engine’s energy which prevents the engine from stalling.
A torque converter is located between the engine and transmission and consists of three key components: the pump, the turbine, and the stator. The pump turns at engine speed and pushes fluid to the turbine, the turbine provides the power necessary for the vehicle to move, and the stator directs fluid from the turbine to the pump. These components all work together to direct the flow of oil through the converter and effectively transmit power from the engine to the transmission.
Hydraulic System
A transmission cannot function properly without transmission fluid to lubricate moving parts, cool components, and facilitate gear shifts. As such, it is essential for a consistent supply of transmission fluid to flow throughout the transmission system. In order to ensure transmission fluid reaches its intended destinations within the automatic transmission, the hydraulic system is essential.
The hydraulic system is essentially an intricate maze of passages which is responsible for sending transmission fluid under pressure to locations all throughout the transmission. Because virtually every function of the transmission is dependent on transmission fluid, the hydraulic system is one of the most important components in a transmission system. If the hydraulic system malfunctions for even a few minutes, the transmission could fail completely.
Oil Pump
Another crucial component of an automatic transmission system is the oil pump. The oil pump is responsible for supplying fluid pressure to the hydraulic system whenever the engine is running. To do so, it draws transmission fluid out from the torque converter and then proceeds to pressurize it. Without such pressure, the transmission fluid would not be able to effectively travel to its intended locations and the systems would cease to function.
Typically, the oil pump is located on the front of the transmission case and mounted between the torque converter and planetary gear set. It is directly connected to the engine crankshaft which allows it to produce pressure any time the engine runs, provided that it is supplied with an ample amount of transmission fluid. If the engine is not running, the oil pump will not be able to provide pressure and many of the components of the transmission will not be able to operate. For this reason, it is impossible to push-start a vehicle that has an automatic transmission without a rear pump.
The oil pump is also directly connected to the hub of the torque converter housing through which the component is driven. It is important to note that while the oil pump is driven by the torque converter, it is not to be confused with the pump component of the torque converter system which was addressed earlier.
Valve Body
The valve body is another basic component of an automatic transmission system. The valve body consists of an intricate collection of passages and channels through which transmission fluid flows. Essentially, the valve body acts as the control center for the automatic transmission by directing the hydraulic fluid through its wide range of valves to various locations throughout the transmission.
By controlling the flow of fluid through its passages by opening or closing valves as necessary, the valve body can appropriately activate specific gears that are suited to various driving situations. Newer automatic transmission systems are equipped with computerized electrical components to control the functions of the valve body.
Because automatic transmission systems are so complex, this list of automatic transmission components is not exhaustive. However, it does provide a general outline of some of the most important and influential parts of your vehicle’s automatic transmission system. If you find that your automatic transmission is experiencing issues due to a malfunction of one of these parts, Transparts Warehouse can help. We provide an extensive range of new and used automatic transmission parts at competitive prices. From transfer case parts to complete transmission rebuild kits, you can find it all here. Contact us today to learn more about our inventory and find the replacement part you need to get your system running smoothly once again.
