One of the key components in an automatic transmission is the torque converter. The torque converter has three stages of operation, and those stages will be our focus today.
STALL
In this phase, there is power being applied by the engine but the turbine cannot rotate. This happens when we are in gear but the vehicle is not moving because we have applied the brakes.
ACCELERATION
In this case, the load is accelerating but it has not reached the desired speed of the impeller. In other words, power from the engine makes the vehicle move when we release the brake, but we are not at maximum efficiency.
COUPLING
In this stage the turbine reaches approximately 90 percent of the speed of the impeller. Here we find the greatest fuel efficiency as the engine and transmission are working in sync with each other.
The stator is what gives the torque converter maximum fuel efficiency. Little or no returning fluid is wasted. The result is that the returning fluid is redirected by the stator so that it aids the rotation of the impeller instead of impeding it.
The torque converter will never reach 100 percent coupling efficiency. That is just the nature of the beast. The efficiency progresses from zero at stall to increased efficiency at acceleration to maximum efficiency at coupling, but it is never perfect. The beauty of CVTs, or Continuously Variable Transmissions, is that they are constantly adjusting to the power input to find maximum efficiency. They can be a bit annoying to drive because of the constant shifting and noise they generate, but they are definitely more efficient.
If all of this sounds complicated that’s because it is. An automatic transmission, and by extension a torque converter, is a complicated piece of machinery. Working on them requires many hours of training and machine know-how. The average home mechanic simply does not have that know-how. That is why it is best to leave repairs of the torque converter and the automatic transmission as a whole to experts who live and breathe this machinery.
At PDQ transmission parts we are dedicated to providing the best in torque converters and automatic transmissions. This is what we do and we are good at it. We are so good that the pros turn to us for their transmission needs. Give us a call the next time you need an expert to work on that automatic transmission. We take the guesswork out of transmissions.
