Which of the following is the driving member of the torque converter and is part of or attached to the shell?

• A. Turbine
• B. Impeller
• C. Lock-up clutch
• D. Stator

Answer: (B)

In a torque converter the driving member is the impeller (pump) because it is attached to the outer shell and driven by the engine. As the engine turns, the impeller spins and pushes transmission fluid outward, creating the flow that transfers torque to the turbine. The turbine, connected to the transmission input shaft, is the driven member, being driven by that fluid. The stator sits between them to redirect the flow for better efficiency, and the lock-up clutch is a separate mechanism that can mechanically couple the impeller and turbine at higher speeds to reduce slip. So the part that actually drives the fluid and is mounted on the housing is the impeller.