What is Torque Converter? How does Torque Converter work?

What is Torque Converter? How does Torque Converter work?

As the name suggests, the torque converter, which is related to the rotational power of the engine, is located between the engine and the transmission. It increases the effect of the torque it receives from the engine up to 2.5 times for a certain period of time. In this way, it gives great support to the first movement of vehicles with automatic transmission. But for this reason, it causes more fuel consumption in continuous stop-start actions. If you are thinking about fuel, you should take care to take off calmly.

We all know that clutches are used in manual transmissions. By depressing the clutch before shifting, you put the engine in neutral and then shift into gear. There is no such vehicle in automatic transmission. A torque converter is used to do this job. This system, which continues its rotation as long as the engine is running, consists of circular covers compatible with its propeller. In the middle, it has another small propeller called the stator.

What is Torque Converter?

What is Torque Converter? Torque converter is a system used in cars with automatic transmission. Because in order to change gears in manual transmission cars, you must first press the clutch pedal and thus neutralize the engine. At the end of this process, you change gear. However, automatic transmission cars do not have a clutch system. They use a torque converter.

The torque converter, which is related to the rotational power of the engine, is an element that increases the effect of torque up to 2.5 times and transfers it to the gearbox. Converter means converter, and you’ll sometimes see it referred to by the name converter. It is of great importance during take-off with its feature of increasing the effect of torque. This element, which is only found in automatic transmission vehicles, is a closed system and contains transmission oil instead of air.

The torque converter has caps reminiscent of propellers. In the middle of these covers, another propeller, smaller than them, is placed. This small propeller is called the Stator.

How Many Parts Does a Torque Converter Consist?

The element consists of 4 basic parts. However, parts such as the lock that increases the efficiency and the spring mechanism that reduces the vibration are also included in this today. Apart from these parts, the system has been working with almost the same principle since the 1950s.

Now let’s examine the basic parts:


There is a thin-bladed propeller fixed to the outer cover inside the impeller. As the motor rotates with the cover, it performs a continuous rotation movement. At the same time, half of the element consists of this part. This part, which rotates continuously with the movement it receives from the engine, moves the transmission oil in the torque converter.


The cover is a closed chamber that is welded together with the impeller body and completes the torque converter body. On the other hand, it is mounted on the engine flywheel and allows the system to move from the engine. The impeller and the cover are welded together and as the engine flywheel rotates, the torque converter starts to rotate thanks to the cover.


The turbine, which is connected to the gearbox, rotates with the circulation of the gearbox oil, which is driven by the impeller. It transfers this rotational movement to the gearbox. If the engine and impeller do not work, the turbine will not turn.


It is the brain of the torque converter. Thanks to its directional blades, it changes the flow of transmission oil in the system from outside to inside and increases efficiency. Its main purpose is to multiply the torque.

If there was no stator, the engine torque would not be transferred to the gearbox by increasing the torque up to 2.5 times for a certain period of time. In addition, instead of the torque converter, there would be a hydraulic coupling that directly transfers the motion. In short, it is the stator that provides the conversion, and as the turbine continues to rotate, it will continue to rotate unilaterally.

How Torque Converter Works?

There is transmission oil in the covers we mentioned above. If the car is running, the fluids hit the turbine, which is connected to the transmission gears. The purpose of this is to convert the power into torque and deliver it to the transmission gears. The operation of the parts of the system gives the necessary information about the torque converter. However, to put it briefly;

The torque converter is connected to the engine by the flywheel. As the flywheel rotates, the cap and impeller connected to it begin to rotate. As the impeller rotates, the transmission oil inside is activated and starts to rotate the turbine. With the rotation of the turbine, the motion is transmitted to the gearbox and the motion of the engine is transferred to the gearbox. During acceleration, the stator does not rotate and is stationary for the torque folding work to take place. Torque folding takes place. As the speed approaches stabilization, the stator starts to rotate with the turbine to prevent resistance and torque folding ends.

If we are driving on a straight road and our vehicle is in manual (manual) transmission, we do not need to brake after we put the engine in neutral when we stop at a red light. But let’s not forget, the same feature does not apply to automatic transmissions. Even if you are on a straight road, you still need to keep the brakes pressed a little. Otherwise, the engine will stop working and your car will stall.

If you are in “D” gear, your vehicle will still continue to move slowly, even if your foot does not step on the accelerator. Because the Torque converter always transmits some of its power uninterruptedly. A system to cut this is not yet used.

If you shift the gear to “N” – which means “N” gear, neutral gear in automatic vehicles – the pump and turbine start to spin in an empty state. Due to this idle rotation, no power can be sent to the transmission. In vehicles with automatic transmission, the Torque converter always continues to rotate as long as the engine is running. That’s why automatic transmission vehicles consume more fuel than manual (manual) transmission vehicles.

What Kind of Effect Do Torque Converter Parts Have on the Operation of the System?

As we mentioned before, the Torque Converter consists of 4 parts. One of the pump’s rotational purposes is to create a vacuum through this rotation. With the effect of this vacuum; will introduce transmission fluid through the center slots. The part that directs the transmission fluid towards the slots is the pump blades.

With the effect of these vacuums, the transmission fluids, which rotate hard around themselves, hit the blades of the turbine and cause them to rotate as well. However, let’s be very careful here: The valves in this section are located in the opposite direction of the turbine. Because when the transmission fluid hits these vanes, it makes them rotate in the opposite direction.

If they were placed flat, they would work in the opposite direction and would not work. For this reason, the blades placed in the opposite direction, as a result of their rotation in the opposite direction, actually show a correct rotation for the Torque Converter system. In mathematics, it’s like minus times minus plus. Otherwise, there is no way for the liquid to escape through these turbines.

How Does the Stator Increase Torque?

The stator, which is located in the middle of the turbine, directs the oil flow from the impeller to the turbine to the interior with its blades. Transmission oil, which passes from a wider flow to a narrower flow, increases its pressure and hits the impeller more severely. Thus, it multiplies the effect of the flow and the torque created by the engine is transmitted to the turbine exponentially.

The torque increase takes place over a period of time. When the speed difference between the impeller and the turbine is equalized, the torque produced by the engine starts to be transferred to the gearbox in the same way and the torque folding ends. The torque converter starts working like a mechanical coupling.

In order to save fuel in automatic transmission vehicles, the part we call the stator is completely deactivated in the models produced recently, allowing the liquid to go directly from the turbine to the pump without an intermediary. In old model automatic transmission vehicles, the stator was automatically disengaged when the last gear was driven. And in some high-class vehicles, if you were traveling at a constant speed in all gears, the stator would still be automatically turned off and it would save fuel.

Now, whether it is a top model or a mid model; whether in last gear or in every gear; whether at constant speed or at variable speed; In any case, engineers continue to produce projects in order to use a statorless torque converter.

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