How Does a Torque Converter Work?

By Mister Transmission

Torque converters are sealed units; their innards rarely see the light of day, and when they do, they’re still pretty hard to figure out!

Imagine you have two fans facing each other. Turn one fan on, and it will blow air over the blades of the second fan, causing it to spin. But if you hold the second fan still, the first fan will keep right on spinning.

That’s exactly how a torque converter works. One “fan,” called the impeller, is connected to the engine (together with the front cover, it forms the outer shell of the converter). The other fan, the turbine, is connected to the transmission input shaft. Unless the transmission is in neutral or park, any motion of the turbine will move the vehicle.

Instead of using air, the torque converter uses a liquid medium, which cannot be compressed – oil, otherwise known as transmission fluid. Automatic transmission cars use a torque converter. This article will discuss why automatic transmission cars need a torque converter and how a torque converter works.

The torque converter in an automatic transmission serves the same purpose as the clutch in a manual transmission.

The engine needs to be connected to the rear wheels so the vehicle will move, and disconnected so the engine can continue to run when the vehicle is stopped. One way to do this is to use a device that physically connects and disconnects the engine and the transmission – a clutch. Another method is to use some type of fluid coupling, such as a torque converter, which is located between the engine and the transmission.

There are three components inside the very strong housing of the torque converter which work together to transmit power to the transmission:

  • Pump
  • Turbine
  • Stator

The pump inside a torque converter is a type of centrifugal pump. As it spins, fluid is flung to the outside, much as the spin cycle of a washing machine flings water and clothes to the outside of the wash tub. As fluid is flung to the outside, a vacuum is created that draws more fluid in at the center.

The fluid then enters the blades of the turbine, which is connected to the transmission (the spline in the middle is where it connects to the transmission.) The turbine causes the transmission to spin, which basically moves your car. The blades of the turbine are curved so that the fluid, which enters the turbine from the outside, has to change direction before it exits the center of the turbine. It is this directional change that causes the turbine to spin.

As the turbine causes the fluid to change direction, the fluid causes the turbine to spin.

The fluid exits the turbine at the center, moving in a different direction than when it entered. The fluid exits the turbine moving opposite the direction that the pump (and engine) are turning. If the fluid were allowed to hit the pump, it would slow the engine down, wasting power. This is why a torque converter has a stator.

The stator resides in the very center of the torque converter. Its job is to redirect the fluid returning from the turbine before it hits the pump again. This dramatically increases the efficiency of the torque converter.

In brief, the torque converter is a type of fluid coupling, which allows the engine to spin somewhat independently of the transmission. It is responsible for pressurizing automatic transmission fluid, a pressurization that supplies the force necessary to shift transmission gears.

A worn or dysfunctional torque converter can prevent transmission fluid from being properly pressurized, which in turn negatively impacts transmission gear function and operation. A systematic checkup by a professional is the best way to isolate the cause of the operating problems and recommend the most effective solution.

If properly tuned, this complex device can have a tremendous impact on your vehicle’s performance, economy and durability, and turn your automatic into a powerhouse!

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After a catastrophic failure of the CVT in my 2013 Subaru Outback I was glad to find such Professionals. Chris, Janna and the Technicians went above and beyond to get my vehicle back in service. Due to Covid-19 restrictions I had to send the Outback to Moncton on a flat deck. All the time it was there I was kept up to date on their every move and diagnoses. From the first Phone Call until I picked it up there was no doubt "This was the right place". Thanks again Mister Transmission !!!
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These days, among all the horror stories you hear about auto shops who either don't know what they're doing or flat out make things worse (and charge mightily either way), it's easy to overlook the real gems who deliver over and above. This shop came highly recommended to me by my son's auto shop class teacher - this on top of the numerous and overall excellent Google reviews. I had transmission shifting problems with an old Dodge pickup truck with which they were initially unfamiliar, and not only did they take on the challenge, research possible causes, and effect what appeared to be logical repairs (at a *very* reasonable price, I might add), when those repairs turned out not to be the root cause of the problem they took it upon themselves to further track down and fix the problem without additional charge (drawing upon their networks of other contacts in the industry to do so). All in a timely manner, keeping well-appraised of their progress every step of the way. As a small business owner myself, I can say that you simply can not expect better service than this. If I could give more than 5 stars I would. Although this is my first experience with them, I will not go anywhere else in the future for transmission work on any vehicle I own.
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Mister Transmission saved us! We had a sudden car issue and were taken care of by Raman. He quickly let us know how to get our vehicle to the shop and was very transparent about the process. He was up front with all costs beforehand and was very responsive, putting us immediately at ease. The fix was completed quickly and even before the estimated time given! We were super pleased with his professionalism, knowledge and workmanship. Car issues suck, but this was an excellent, pain free, no hassle, process. Highly recommend!Thank you Raman & Mister Transmission team!
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Michael James
Paul was the gentleman who was taking care of my appointment. He was very informative with the issues I was having with my transmission. He was honest in giving his opinion on what course of repair I should use to fix my issue. His customer service and personability were exemplar. The repair was done in a timely manner and he even did some cleaning of the engine bay of my car without mentioning it. For any transmission or drive system repairs I wouldn't recommend any shop other than this one.
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