If we should give a definition to the torque converter we should say it is generally a type of hydrodynamic fluid coupling which is used to transfer rotating power from a prime mover, such as internal combustion engine or electric motor, to a rotating driven load.
This component is one of the least understood elements in an automatic equipped car.
You should know this component has a few different functions.
So, the first thing you should know is that there is no direct link between the crankshaft and the transmission input shaft. This means that the first function of the converter is to connect the crankshaft and the input shaft so the engine can move the car. This thing is accomplished through making use of a fluidic coupling effect.
The converter also replaces the clutch which is required in a manual transmission. And this is how an automatic transmission vehicle can come to a stop while still being in gear. This converter also acts like a torque multiplier or extra gear ratio to help the car moving from a stop.
Basically, a torque converter is made of four major components that have an important role in making the converter work. The first component is called the impeller or pump. This component is connected directly to the inside of the converter housing and it is turning anytime that the engine rotates. The next component is the turbine which is also the output or driven member. The transmission’s input shaft is splined to it. The turbine is not connected to the converter housing and it can rotate completely independently of it. Another component is the stator assembly. Its function is to redirect the flow of fluid between the impeller and the turbine, which gives the torque multiplication effect from a standstill. The final component is the lock up clutch. At highway speeds this clutch can be applied and it will ensure a direct mechanical connection between the crankshaft and the input shaft, which will result in an optimal efficiency between the engine and the transmission. The application of this clutch is basically controlled by the vehicle’s computer activating a solenoid in the transmission.
So, what we should consider regarding the torque converter is that it has the ability to multiply torque when there is a substantial difference between input and output rotational speed, thus providing the equivalent of a reduction gear. Some of these devices are equipped with a temporary locking mechanism which rigidly binds the engine to the transmission when their speeds are nearly equal, and thus avoid slippage and a resulting loss of efficiency.