What are the two phases of torque converter operation?

What are the two phases of torque converter operation?

• A. The torque multiplication phase and lockup phase
• B. Lock-up phase and torque multiplication phase
• C. The torque multiplication phase and coupling phase
• D. The stator phase and lock-up phase

Answer: (C)

Torque converter operation happens in two stages. First is torque multiplication: the impeller pushes fluid that slips relative to the turbine, and because the stator redirects that flow, the turbine ends up delivering more torque than the engine is actually producing at the same speed. This stage provides high torque at low to moderate speeds. The second stage is the coupling (lock-up) phase: once enough speed is reached, a clutch inside the converter locks the impeller to the turbine, creating a direct mechanical link. That eliminates most slip and greatly improves efficiency and throttle response. So the two phases are torque multiplication and coupling (lock-up). The term coupling here is another way to describe the lock-up action.

Torque converter operation happens in two stages. First is torque multiplication: the impeller pushes fluid that slips relative to the turbine, and because the stator redirects that flow, the turbine ends up delivering more torque than the engine is actually producing at the same speed. This stage provides high torque at low to moderate speeds.

The second stage is the coupling (lock-up) phase: once enough speed is reached, a clutch inside the converter locks the impeller to the turbine, creating a direct mechanical link. That eliminates most slip and greatly improves efficiency and throttle response.

So the two phases are torque multiplication and coupling (lock-up). The term coupling here is another way to describe the lock-up action.