With no this link, a car wouldn't have the capacity to come to a complete quit without the need of killing the motor. Autos with automated transmissions don't have any clutch that disconnects the transmission through the engine. As an alternative, they use a device known as a torque converter. https://torque-converter-clutch62838.dm-blog.com/34267884/5-simple-statements-about-torque-converter-clutch-explained