Which term describes the phase where the torque path is directly coupled during lock-up?

• A. Torque multiplication phase
• B. Coupling phase
• C. Stator phase
• D. Pump phase

Answer: (B)

When lock-up happens, the system moves into a state where the torque path becomes a solid mechanical link rather than a fluid-driven flow. That direct connection is called the coupling phase. The lock-up clutch engages to connect the input and output sides, so there’s little to no slip and the torque transfer is essentially 1:1, which is why efficiency improves at cruising speeds.

The torque multiplication phase describes the period when torque is increased through fluid coupling with slip, before lock-up engages. The stator and pump terms refer to other parts or effects of the torque converter and aren’t describing the direct mechanical coupling that occurs during lock-up.