The six-speed automatic transmission consists of five planetary gears, four friction discs, three brake bands and a hydraulic control unit.
Working principle:
1. Torque transmission: The engine transmits power to the transmission shaft through a torque converter.
2. Planetary gears: Planetary gears consist of a center gear, planetary gears and a sun gear. These gears are interchangeable and allow different gear ratios to be achieved.
3. Friction Discs: Friction discs are used to engage and disengage various gears. When a disc is turned on, it meshes with another disc or drum, transferring power.
4. Brake Bands: Brake bands are used to hold various planetary gears, preventing them from rotating. When the belt is engaged, it tightens around the planetary gear, stopping it.
5. Hydraulic control unit: The hydraulic control unit controls the fluid flow in the gearbox. The fluid is used to operate friction discs and brake bands, as well as to shift gears.
6. Sensors and computer: Sensors in the transmission monitor various parameters such as speed, engine speed and gear selector position. This information is sent to a computer, which determines which gear to play.
Gear shift:
The hydraulic control unit uses fluid pressure to engage or release friction discs and brake bands. This allows for smooth gear changes and optimized vehicle performance.
Gear ratios:
Each gear has its own gear ratio. First gear provides the smallest gear ratio and is used for moving from a standstill. Higher gears have higher ratios and are used for higher speeds and better fuel economy.
Torque converter:
The torque converter is built into the transmission and is used to transfer torque from the engine to the transmission. It acts as a friction clutch and also provides torque multiplication.