Which of the following cannot be coupled directly to the engine crankshaft or to the flywheel?

Which of the following cannot be coupled directly to the engine crankshaft or to the flywheel?

• A. Converter turbine
• B. Torque converter
• C. Hydraulic clutch piston
• D. Backing plate

Answer: (B)

The key idea is how torque is transmitted: some parts are connected to the engine by a direct, rigid link, while others transfer torque through fluid or via separate assemblies. A torque converter transfers torque primarily through fluid inside the housing, not by a direct shaft-to-shaft connection to the engine crankshaft or to the flywheel. Because of that, the entire torque converter cannot be coupled directly to the engine crankshaft or the flywheel—its job is to mediate torque between the engine and transmission without a rigid mechanical link to the crank or flywheel. The other items are components that either reside around rotating parts or are actuators and mounts, not the rigid drive link between engine and transmission.

The key idea is how torque is transmitted: some parts are connected to the engine by a direct, rigid link, while others transfer torque through fluid or via separate assemblies. A torque converter transfers torque primarily through fluid inside the housing, not by a direct shaft-to-shaft connection to the engine crankshaft or to the flywheel. Because of that, the entire torque converter cannot be coupled directly to the engine crankshaft or the flywheel—its job is to mediate torque between the engine and transmission without a rigid mechanical link to the crank or flywheel. The other items are components that either reside around rotating parts or are actuators and mounts, not the rigid drive link between engine and transmission.