Gears in Automatic Transmission Car
Introduction
An automatic transmission is a type of transmission that automatically changes gears as the vehicle speeds up or slows down. This makes driving easier and more convenient, as the driver does not have to worry about shifting gears manually.
Automatic transmissions use a variety of different gears to achieve this. The most common type of automatic transmission is a planetary gearset. This type of gearset consists of a sun gear, a planet carrier, and a ring gear. The sun gear is connected to the input shaft, the planet carrier is connected to the output shaft, and the ring gear is connected to the housing.
As the input shaft rotates, the sun gear causes the planet carrier to rotate. This, in turn, causes the ring gear to rotate. The speed ratio between the input shaft and the output shaft is determined by the number of teeth on each of the gears.
In addition to planetary gearsets, automatic transmissions can also use other types of gears, such as spur gears, helical gears, and bevel gears. These different types of gears are used to achieve different speed ratios and torque capacities.
Types of Gears
There are three main types of gears used in automatic transmissions:
* Planetary gears are the most common type of gear used in automatic transmissions. They are made up of a sun gear, a planet carrier, and a ring gear. The sun gear is connected to the input shaft, the planet carrier is connected to the output shaft, and the ring gear is connected to the housing.
* Spur gears are used to transmit power between parallel shafts. They are the simplest type of gear and are relatively inexpensive to manufacture.
* Helical gears are used to transmit power between intersecting shafts. They are more efficient than spur gears and produce less noise.
* Bevel gears are used to transmit power between shafts that are at an angle to each other. They are often used in rear-wheel drive vehicles.
Gear Ratios
The gear ratio of an automatic transmission is the ratio of the number of teeth on the input gear to the number of teeth on the output gear. The gear ratio determines the speed and torque output of the transmission.
A higher gear ratio will result in a lower output speed and a higher torque output. This is useful for climbing hills or towing heavy loads. A lower gear ratio will result in a higher output speed and a lower torque output. This is useful for accelerating or cruising at high speeds.
Most automatic transmissions have multiple gear ratios. This allows the transmission to select the best gear ratio for the current driving conditions.
Shifting Gears
Automatic transmissions use a variety of different mechanisms to shift gears. The most common type of shifting mechanism is a hydraulic valve body. This valve body is controlled by the transmission control unit (TCU). The TCU uses a variety of sensors to determine the current driving conditions and selects the appropriate gear ratio.
Other types of shifting mechanisms include:
* Mechanical linkage: This type of shifting mechanism uses a mechanical linkage to connect the shift lever to the transmission.
* Electronic linkage: This type of shifting mechanism uses an electronic signal to connect the shift lever to the transmission.
* Continuously variable transmission (CVT): This type of transmission does not use gears. Instead, it uses a belt or chain that can change its effective diameter. This allows the transmission to provide an infinite number of gear ratios.
Conclusion
Gears are an essential part of automatic transmissions. They provide the necessary speed and torque ratios to allow the vehicle to operate efficiently under a variety of driving conditions.
