Which part connects the engine to the vehicle's transmission?

The flywheel is the component that connects the engine to the vehicle's transmission in manual transmission systems. It serves several important functions, such as storing energy and smoothing out the power delivery from the engine to the transmission. The flywheel is bolted directly to the engine's crankshaft, allowing it to rotate with the engine.

In addition, it provides a surface for the clutch plate to engage and disengage. This engagement is crucial during gear changes in a manual transmission. By maintaining momentum, the flywheel helps to minimize vibration and improve the overall driving experience.

The other components mentioned play different roles. The torque converter, for example, is used in automatic transmissions to allow for a smooth transition of power from the engine to the transmission without the need for a clutch. The clutch plate is part of the system that engages and disengages the flywheel and allows for gear changes in manual systems, but it does not connect the engine directly to the transmission. Lastly, the axle is responsible for transferring power from the transmission to the wheels, not connecting the engine to the transmission.