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Torque Converter: Operating Principle of the Torque Converter
Release date:
2021-07-20 17:15
Source:
Dana torque converter : The torque converter is something most drivers use every day—have you ever wondered how it works?
Anyone who’s driven a manual knows that when stopped at a red light, if you don’t shift into neutral and depress the clutch, the engine and wheels remain rigidly connected, causing the car to stall. So why doesn’t an automatic vehicle stall when you keep your foot on the brake in Drive?
Here, we’ll leave you with a question. Some people say that when you press the brake in D gear, it’s as if the transmission and the brakes are competing with each other, which can increase fuel consumption and engine RPM. Is this claim accurate?
Therefore, this article focuses primarily on the core component of the automatic transmission: the hydraulic torque converter.
For vehicles with automatic transmissions, there is no driver‑operated clutch; therefore, as long as the gear selector is in D, the car will move forward. While this statement isn’t entirely precise, it’s essentially correct. So why doesn’t the car move when the traffic light turns red? The transmission shifts into neutral, but the vehicle remains stationary.
When a car catches fire, the engine must keep turning; as long as the vehicle is in motion, it continues to deliver power. However, if the car remains stationary, we can achieve the same effect by shifting into neutral or disengaging the clutch, thereby breaking the connection between the wheels and the engine. Consequently, in vehicles equipped with automatic transmissions, a component is required to absorb this energy—namely, the torque converter.
Working principle of the hydraulic torque converter
The operating principle of a hydraulic torque converter is akin to that of two opposing fans: when one fan is running, the other, which is stationary, gets blown by the airflow. This analogy vividly illustrates the working relationship between the pump impeller and the turbine within the torque converter. However, a detailed explanation of its operation is rather complex.
After power is transmitted, it drives the pump impeller, which is connected to the torque converter housing. The pump impeller agitates the automatic transmission fluid within the converter, causing the turbine to rotate. This creates a circulating flow of ATF throughout the housing. Under the influence of centrifugal force, the ATF is flung outward by the pump impeller, propelled toward the front‑mounted turbine, and then flows back toward the center, returning to the side of the pump impeller. This continuous循环 transfers power to the turbine, which is linked to the gearbox.
However, this component alone, along with the transmission mechanism, is merely referred to as a hydraulic coupling. To qualify as a torque converter, the shape of the turbine blades must be modified. In this configuration, when the ATF recirculates back to the pump impeller, it flows in the opposite direction to the impeller’s rotation, creating an impact. Therefore, to function as a torque converter, an additional component—the stator—is required. The stator is positioned between the pump impeller and the turbine; it directs the flow of ATF within the housing and is secured to the housing via a one-way clutch.
With the stator, the torque converter acquires its “torque‑conversion” capability. When the pump impeller and turbine rotate at significantly different speeds, the output torque increases accordingly. At this point, the torque converter functions like a continuously variable transmission, using the speed difference to amplify torque. Meanwhile, the stator remains stationary, redirecting the ATF flow. As the speed difference diminishes and the pump and turbine become coupled or locked, the torque approaches equality, eliminating the need for further torque multiplication. The stator then follows the pump impeller and turbine in the same rotational direction, preventing the ATF from churning on its own and thereby avoiding power losses.
Beijing Yihaowei Power Equipment Co., Ltd. specializes in Dana, Dana Spicer, Dana agency services, and Dana repair. Its product lineup includes Dana drive axles, Dana torque converters, Dana transmissions, Clark transmission‑driven axles, and Allison transmission spare parts, among others. Established in 2002, the company obtained authorization from Dana in 2004, becoming one of more than 60 service centers worldwide. Today, we operate one of China’s largest warehouses for powertrain components. Backed by a highly skilled professional team, we provide expert technical support and genuine, high‑quality product solutions to numerous equipment manufacturers, end users, and distributors both domestically and internationally.
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