Which part of the lock-up converter is responsible for providing lock-up?

The part of the lock-up converter responsible for providing lock-up is the clutch. In an automatic transmission, the torque converter uses a lock-up clutch to engage the engine's flywheel directly to the turbine. This engagement reduces slip, allowing for a more efficient transfer of power from the engine to the drivetrain, particularly at higher speeds. When the clutch is engaged, it effectively locks the turbine to the engine, improving fuel efficiency and performance.

The stator, pump, and turbine all play important roles in the operation of the torque converter, but they do not directly create the lock-up function. The stator is essential for directing fluid flow and enhancing torque multiplication, while the pump generates the hydraulic pressure necessary for operation. The turbine converts the fluid energy from the pump into mechanical energy, but it is the clutch that physically locks these components together when needed.