How does a Torque Converter Work

Ever wondered how does the gear work in a car and how the gear ratios are changed automatically while the vehicle is in the motion? Well, it is the work of the car's unsung hero, the torque converter. Well, I might be personifying it a tad bit, when I say that it is the unsung hero, because you don't use that adjective for a machine. So then, to put it in better words, it is a significant part of all heavy vehicles, marine propulsion systems and industrial power transmission systems.

So first of all what is a torque converter? Basically, a torque converter is a type of a hydrodynamic device, which is required to carry the mechanical power, generated through the rotation of a mechanical device. A torque converter, specifically transfers power from an internal combustion engine or an electric motor, to a load driven by the rotation of a machine or the carrier. It serves as a mechanical clutch, separating the load from the power source.

Functioning of a Torque Converter
After elucidating on what a torque converter is, let us check out, 'how does a torque converter work'. To know that, there has to be a mention of the important rotating parts of a torque converter. They are:

• A pump, which is driven mechanically, by the prime mover.
• Turbine, which propels the load.
• A stator, which is a liaison between the pump and the turbine. The oil flow returning from the turbine to the pump is modified by this stator.

When you talk about the functioning of a torque converter, there are basically three operational stages.

Stall: This happens when the pump is being propelled and is driven by the prime mover, but the turbine is still not driven into rotation. In vehicles, especially cars, it happens when it is in gear, but the movement of the vehicle has been stalled because the driver has applied the brakes. This stage is called stall, because as the vehicle begins to move, there is a large difference between the pump and the turbine speeds.

Acceleration: In this stage the vehicle or the load has started moving faster. Still, there is a big gap between the speed of the turbine and the pump. Here, one can find some torque multiplication. Torque multiplication refers to the torque (the characteristic of force, to rotate an object about an axis) provided to the turbine output shaft. In this stage, it is less than the stall conditions. However, the multiplication depends upon the difference between the speed of the turbine and the pump. It is also dependent upon the design of the machine as well.

Coupling: Coupling refers to a phase when the turbine has attained about 90% of the speed of the pump. Now, there is hardly any torque multiplication. In the new age automobiles, this is where the lock up clutch is used. Coupling refers to a process of enhancing fuel efficiency. The torque converter acts like a mechanical clutch, separating the load and the power source.

Now lets check out some symptoms of bad torque converter. For starters, when it comes to cars, the first symptom that a torque converter has gone kaput, is the stalling of the vehicle while in forward gear or reverse gear, simply slowing it down to a complete stop. Another symptom is of the converters experiencing shudders, when in the overdrive mode. A bad torque converter can prevent a vehicle from generating sufficient power. Weird sounds, like sounds resembling grinding or whistling, can be heard when a torque converter is dysfunctional. When the gearbox cannot give a proper gear switching, it can be safely assumed that the torque converter is not working properly.

Here are a few torque converter problems:

• Overheating: It is the most common problem occurring in a torque converter. Persistent high levels of transmission slippage, hampers the converter's ability to dissipate heat. This causes damage to the elastomer seals, retaining fluid in the converter.
• Seizure of the stator clutch: Many a times, a seizure in the stator clutch is caused by major loading and consequent disturbance of the clutch components.
• Ballooning: Persistent application under excessive loading, coupled with running the torque converter at a very high RPM can distort the shape of the converter's housing. This is called ballooning. It can cause the converter housing to burst or rupture.
• Deformation of the blade or turbine: Excessive heating of the converter, can lead to the breakage or deformation of the turbine and pump. They can be separated from their hubs or annular rigs, or may break in fragments.

This was my attempt in explaining 'how does a torque converter work', with almost all its intricacies and mechanical jargon. Those who are in this field, surely know the nitty gritties of a torque converter! But I am sure that even those who did not know, would now surely know what it is, especially after reading my article!