Methods of transmitting torque from the engine to the automatic transmission
There are two main ways to transfer torque from the engine to an automatic transmission (automatic transmission):
1. Torque converter
The torque converter is a device consisting of three wheels:
* Pump is a wheel connected to the engine.
* Turbine is a wheel connected to an automatic transmission.
* Stator is a wheel located between the pump and turbine.
The pump is rotated by the engine and creates a flow of transmission fluid. The fluid flow is directed to the turbine, causing it to rotate. The stator changes the direction of fluid flow, causing the turbine to rotate faster than the pump. Thanks to this, the gear ratio is achieved and more torque is transferred from the engine to the automatic transmission.
2. Mechanical clutch
Some automatic transmission designs use a mechanical clutch instead of a torque converter. The clutch consists of two disks:
* Primary disk – connected to the motor.
* Secondary disk – connected to the automatic transmission.
When the motor is turned on, the primary disk rotates. The friction linings on the discs are pressed against each other, transmitting torque from the engine to the automatic transmission.
Selecting a torque transmission method
The choice of torque transmission method depends on the vehicle performance requirements, such as:
* Smooth Ride – A torque converter provides a smoother ride, while a mechanical clutch may cause some kickback when shifting gears.
* Fuel Savings – A torque converter is less efficient than a mechanical clutch because some of the energy is lost to heat.
* Towing Power – Torque converters provide more torque at low rpm, which is useful for towing.
* Cost – Torque converters are more expensive to manufacture than mechanical clutches.
Most modern automatic transmissions use a torque converter because it provides smooth operation and additional torque. However, mechanical clutches are sometimes used in high-performance vehicles or vehicles with particularly stringent fuel economy requirements.