The transformation ratio of an automatic transmission torque converter (automatic transmission) is the ratio of gear ratios at various operating speeds of the torque converter.
Transformation ratio at the fluid coupling (pump wheel and turbine wheel)
* When starting off: The transformation coefficient is approximately 2.5-3.5. This provides high torque at low engine speeds to overcome vehicle inertia and get moving.
Transformation ratio at the reactor (pump wheel, turbine wheel and reactor)
* At medium speeds: The transformation ratio gradually decreases and reaches 1.0-1.2 at a speed of about 40-50 km/h. This corresponds to direct drive, where the turbine wheel rotates at the same speed as the pump wheel.
* At high speeds: The transformation ratio can become even less than 1.0, resulting in a multiplier or gear shift effect. This helps save fuel when driving at high speeds.
Thus, the transformation ratio of the automatic transmission torque converter varies depending on the vehicle speed and provides:
* High torque at low speeds for starting and acceleration
* Direct drive at medium speeds for efficiency
* Torque multiplication at high speeds to save fuel