The torque _____________ phase occurs any time the torque converter is increasing the engine's torque output to the transmission's input shaft.

The torque _____________ phase occurs any time the torque converter is increasing the engine's torque output to the transmission's input shaft.

• A. Multiplication phase
• B. Coupling phase
• C. Lock-up
• D. Cool down

Answer: (A)

Torque multiplication in a torque converter is the process that boosts the torque sent from the engine to the transmission input when there is slip between the impeller and turbine. At low speeds, the fluid between the rotating parts redirects energy in a way that multiplies the torque the engine produces, so the transmission input sees more torque than the engine alone would provide. This is the phase where the converter is actively increasing torque transfer, especially as the vehicle starts moving or accelerates from low speeds. As speed increases, the slip reduces and the multiplier effect diminishes, moving toward a near 1:1 transfer known as the coupling phase, where torque transfer is more direct and less amplified. The lock-up phase is when a clutch inside the converter actually locks the impeller and turbine together to create a direct drive with essentially no slip, so there’s no torque multiplication. The cool down term isn’t a functional phase of torque transfer. So the phase described—where the torque converter increases the engine’s torque output to the transmission input shaft—is the multiplication phase.

Torque multiplication in a torque converter is the process that boosts the torque sent from the engine to the transmission input when there is slip between the impeller and turbine. At low speeds, the fluid between the rotating parts redirects energy in a way that multiplies the torque the engine produces, so the transmission input sees more torque than the engine alone would provide. This is the phase where the converter is actively increasing torque transfer, especially as the vehicle starts moving or accelerates from low speeds.

As speed increases, the slip reduces and the multiplier effect diminishes, moving toward a near 1:1 transfer known as the coupling phase, where torque transfer is more direct and less amplified. The lock-up phase is when a clutch inside the converter actually locks the impeller and turbine together to create a direct drive with essentially no slip, so there’s no torque multiplication. The cool down term isn’t a functional phase of torque transfer.

So the phase described—where the torque converter increases the engine’s torque output to the transmission input shaft—is the multiplication phase.